Please need advice

[Guest Peter Lank]

Hi,I have 20,000 gal pool,and will use Mineral Springs sanitizer MS-10,can i use regular soft water salt with the system?

Thanks.

[Guest rgreiner]

We do not recommend anything other than the mineral spring beginnings and renewal for use in the pool. There are far too many impurities in other salts and the renewal helps keep the cell clear of scale. Check with your local BioGuard dealer for more info.

[waterbear]

Mineral Springs generator is manufactured by goldline controls for biogard. Goldline recoomeds 99.5% pure solar salt for their units. Interestingly, the goldline units can be set to read salt ppm or mineral ppm. I have one of these units and asked their tech support what the difference is. they told me the minerals setting is for use with the Mineral Springs salt which has all kinds of added (read unnecesary) stuff. I personally would rather balalce my water and check my salt levels so I only put in what I need insead of putting in a chemical brew and hoping for the best. Also, a 40 lb bag of morton pool salt costs me about 5 dollars while a bag of mineral springs renewal is quite a bit more. I use baking soda (sodium bicarbonate, sodium hydrogen carbonate--alkalikity increaser), borax (ph up substitute) or washing soda (sodium carbonate--ph up) and muriatic acid for water balance. and add stabalizer when the level drops below about 40 ppm. I get everything I need except for the stabelizer and the muriatic acid which I get a the local pool store. I test my water with a drop based test kit (can be had for as little as 15 dollars for a 5 way test!) Knowledge is power and can save you a lot of money!

[Brulan1]

Mineral Springs generator is manufactured by goldline controls for biogard. Goldline recoomeds 99.5% pure solar salt for their units. Interestingly, the goldline units can be set to read salt ppm or mineral ppm. I have one of these units and asked their tech support what the difference is. they told me the minerals setting is for use with the Mineral Springs salt which has all kinds of added (read unnecesary) stuff. I personally would rather balalce my water and check my salt levels so I only put in what I need insead of putting in a chemical brew and hoping for the best. Also, a 40 lb bag of morton pool salt costs me about 5 dollars while a bag of mineral springs renewal is quite a bit more. I use baking soda (sodium bicarbonate, sodium hydrogen carbonate--alkalikity increaser), borax (ph up substitute) or washing soda (sodium carbonate--ph up) and muriatic acid for water balance. and add stabalizer when the level drops below about 40 ppm. I get everything I need except for the stabelizer and the muriatic acid which I get a the local pool store. I test my water with a drop based test kit (can be had for as little as 15 dollars for a 5 way test!) Knowledge is power and can save you a lot of money!

That system sounds really cool. We sell something called the poolpilot which is a salt generator made by aquacal the same company that makes those awsome heat pumps. Electronators have been around for over 30 years but now they are called salt generators

[sharkman009]

Mineral Springs generator is manufactured by goldline controls for biogard. Goldline recoomeds 99.5% pure solar salt for their units. Interestingly, the goldline units can be set to read salt ppm or mineral ppm. I have one of these units and asked their tech support what the difference is. they told me the minerals setting is for use with the Mineral Springs salt which has all kinds of added (read unnecesary) stuff. I personally would rather balalce my water and check my salt levels so I only put in what I need insead of putting in a chemical brew and hoping for the best. Also, a 40 lb bag of morton pool salt costs me about 5 dollars while a bag of mineral springs renewal is quite a bit more. I use baking soda (sodium bicarbonate, sodium hydrogen carbonate--alkalikity increaser), borax (ph up substitute) or washing soda (sodium carbonate--ph up) and muriatic acid for water balance. and add stabalizer when the level drops below about 40 ppm. I get everything I need except for the stabelizer and the muriatic acid which I get a the local pool store. I test my water with a drop based test kit (can be had for as little as 15 dollars for a 5 way test!) Knowledge is power and can save you a lot of money!

Thats true knowledge can save you money but if you make a mistake and add something to your pool water that leaves you with stains in your pool that $5.00 bag of salt is not going to seem like such a good deal.

A replastering job in our area is 5-$6000.00.

The chemicals that you read are unnecesary all have a purpose. If you dont want those things in your water thats fine but I would not recmmend adding regular water softener salt.

[Brulan1]

Thats true knowledge can save you money but if you make a mistake and add something to your pool water that leaves you with stains in your pool that $5.00 bag of salt is not going to seem like such a good deal.

A replastering job in our area is 5-$6000.00.

The chemicals that you read are unnecesary all have a purpose. If you dont want those things in your water thats fine but I would not recmmend adding regular water softener salt.

that is a good point.

[waterbear]

I have talked to tech support at Goldinecontrols about the type of salt to use. They told me that PLAIN water softener salt (no iron removers or water softener conditioners) thatis 99.5% pure salt is fine, as is solar salt. The pellets will take longer to dissolve than the solar which are large crystals. Pool salt is smaller crystals which dissolve faster. There is still a need to balance your water. Adding a bag of a chemical mix every monthis NOT going to balance your water. If the mix contains CYA(stabilizer) you levels will continue to go up and eventually you might get algae blooms since high CYA levels require running higher free chlorine levels. Most SWG companies recommend running CYA at 50-80 ppm. You still need to monitor total alkalinity, carbonate hardness (for plaster pools or pools with heaters or grouted tilework--moot point for vinyl and fiberglass), pH, and free and combinde chlorine levels. Dont rely on test strips, they are notoriously inaccurate. Get a drop based test kit. Cheap ones are available at Walmart that will test all 5 of the above parameters but the Taylor K-2005 (good) or K-2006 (best choice) are much more accurate. For pH control you need Muriatic acid (dry acid is OK but if you look at the chemistry of generating chlorine HCL [muriatic acid} is a better choice) for raising pH since SWG's produce sodium hydroxide as a byproduct and you will have a constant upward drift in pH. Adjust the pH once it drifts above 7.8. In the rare event that you need to raise pH either Sodium Carbonate (commen washing soda from the grocery store--exactly the same thing as pH increaser) or Borax from the grocery store will do it with Borax being a better choice since it introduces a borate/boric acid buffer system in addition to the carbonate/carbonic acid buffer system that is in your pool which can "gas off' and affect your total alkalinity readings. To adjust total alkalinity you need Sodium Hydrogen Carbonate which is also called Sodium Bicarbonate. They are the same chemical. You can buy the industrial grade at a pool store or the much purer USP grade for less money at the grocery store under the name of "Baking Soda" . Aim for total Alkalinity between 80-120 ppm. Calcium levels are important for plaster pools. Most sources recommend levels between 200-400 ppm. Not much of an issue for fiberglass or vinyl unless you have a heater, grouted tile work, very hard, or very soft water and then you might need to make adjustments. Ideally you should check your Saturation Index or Hamilton Index to see if you water is balanced. There is still a lot of debate about whether the Saturation Index is a useful measurement for pools since it was designed for closed boiler systems to help prevent scaling and corrosion. Free chlorine levels should be checked at least weekly as should pH and if you are running 50-80 ppm CYA should be about 2 or 3 ppm with combined chlorine < .5 ppm. If combined chlorine is higher than that set your SWG to superchlorinate OR you could shock with Sodium Hypochlorite which is available in strennths from 5.25 % to 12 % or higher. Only difference is price and how much you need to use for a given level of free chlorine (shock level is usually 15 ppm or higher depending on your CYA levels and needs to be maintained at that level for about 24 hours). Here is a tip 5.25% AND 6% Sodium Hypochlorite are available at the grocery store and are called Regular Unscented Chlorine Bleach (5.25%) and Ultra Unscented Chlorine Bleach(6%). At your friendly neighborhood pool store you will usually find liquid chorine (6% Sodium Hypochlorite) and liquid shock (12% sodium hypochlorite). Compare prices, it's interesting. Also be aware that the stronger the concentration of sodium hypochlorite in the solution the faster it losses it's strength so that bottle of 12% liquid shock that you bought 2 months ago might only be 6% now !

Do you need to add anything else to you pool with a SWG--maybe. If your fill water has metals you might need a seqesterant. Dp you need to add Algicide? Possibly, but if you balance your water and run your free chloine levels at 2-3 ppm and make sure your CYA levels stay between 50-80 ppm most likely not!

How about clarifiers, flocs, water "optimizers" , enzymes,etc.? IF you follow the above recommendations and keep your water balanced and your filter and pool clean they probably are not necessary but if you like to $pend money go ahead!

Once again I say "Knowledge is power and it can save you a lot of money!"

[sharkman009]

I have talked to tech support at Goldinecontrols about the type of salt to use. They told me that PLAIN water softener salt (no iron removers or water softener conditioners) thatis 99.5% pure salt is fine, as is solar salt. The pellets will take longer to dissolve than the solar which are large crystals. Pool salt is smaller crystals which dissolve faster. There is still a need to balance your water. Adding a bag of a chemical mix every monthis NOT going to balance your water. If the mix contains CYA(stabilizer) you levels will continue to go up and eventually you might get algae blooms since high CYA levels require running higher free chlorine levels. Most SWG companies recommend running CYA at 50-80 ppm. You still need to monitor total alkalinity, carbonate hardness (for plaster pools or pools with heaters or grouted tilework--moot point for vinyl and fiberglass), pH, and free and combinde chlorine levels. Dont rely on test strips, they are notoriously inaccurate. Get a drop based test kit. Cheap ones are available at Walmart that will test all 5 of the above parameters but the Taylor K-2005 (good) or K-2006 (best choice) are much more accurate. For pH control you need Muriatic acid (dry acid is OK but if you look at the chemistry of generating chlorine HCL [muriatic acid} is a better choice) for raising pH since SWG's produce sodium hydroxide as a byproduct and you will have a constant upward drift in pH. Adjust the pH once it drifts above 7.8. In the rare event that you need to raise pH either Sodium Carbonate (commen washing soda from the grocery store--exactly the same thing as pH increaser) or Borax from the grocery store will do it with Borax being a better choice since it introduces a borate/boric acid buffer system in addition to the carbonate/carbonic acid buffer system that is in your pool which can "gas off' and affect your total alkalinity readings. To adjust total alkalinity you need Sodium Hydrogen Carbonate which is also called Sodium Bicarbonate. They are the same chemical. You can buy the industrial grade at a pool store or the much purer USP grade for less money at the grocery store under the name of "Baking Soda" . Aim for total Alkalinity between 80-120 ppm. Calcium levels are important for plaster pools. Most sources recommend levels between 200-400 ppm. Not much of an issue for fiberglass or vinyl unless you have a heater, grouted tile work, very hard, or very soft water and then you might need to make adjustments. Ideally you should check your Saturation Index or Hamilton Index to see if you water is balanced. There is still a lot of debate about whether the Saturation Index is a useful measurement for pools since it was designed for closed boiler systems to help prevent scaling and corrosion. Free chlorine levels should be checked at least weekly as should pH and if you are running 50-80 ppm CYA should be about 2 or 3 ppm with combined chlorine < .5 ppm. If combined chlorine is higher than that set your SWG to superchlorinate OR you could shock with Sodium Hypochlorite which is available in strennths from 5.25 % to 12 % or higher. Only difference is price and how much you need to use for a given level of free chlorine (shock level is usually 15 ppm or higher depending on your CYA levels and needs to be maintained at that level for about 24 hours). Here is a tip 5.25% AND 6% Sodium Hypochlorite are available at the grocery store and are called Regular Unscented Chlorine Bleach (5.25%) and Ultra Unscented Chlorine Bleach(6%). At your friendly neighborhood pool store you will usually find liquid chorine (6% Sodium Hypochlorite) and liquid shock (12% sodium hypochlorite). Compare prices, it's interesting. Also be aware that the stronger the concentration of sodium hypochlorite in the solution the faster it losses it's strength so that bottle of 12% liquid shock that you bought 2 months ago might only be 6% now !

Do you need to add anything else to you pool with a SWG--maybe. If your fill water has metals you might need a seqesterant. Dp you need to add Algicide? Possibly, but if you balance your water and run your free chloine levels at 2-3 ppm and make sure your CYA levels stay between 50-80 ppm most likely not!

How about clarifiers, flocs, water "optimizers" , enzymes,etc.? IF you follow the above recommendations and keep your water balanced and your filter and pool clean they probably are not necessary but if you like to $pend money go ahead!

Once again I say "Knowledge is power and it can save you a lot of money!"

You seem to be pretty knowledgable on water chemistry however There are a few points that I would question. First you said if you use stabilized chlorine your levels of stabilizer will climb and you will eventually get algae blooms. Your sanitizer levels will climb if you are dealing with a system that you do not backwash as you are not removing water from the pool. However on sand filter or de systems you usually are removing enough water from the pool for the levels to be no problem.

The other statement that you made about test strips not being accurate is not correct. Test strips are as accurate as any DPD or OTO test and in fact they use the same reagents to get their readings. Test strips do have a shelf life as do liquid test reagents.

There is no debate that I am aware of as to wether Saturation index is important on pool water. Saturation index is an accepted measure to determine if water is corrosive or scale forming and we use this calculation daily.

I would recommend the use of algacides to prevent algae from growing in a pool as there are forms of algae that can grow in water with a free chlorine level at 3ppm. CYA does not effect the activity of your chlorine. If you are refering to chlorine lock that theory has been proven to be false.

[tony]

I have talked to tech support at Goldinecontrols about the type of salt to use. They told me that PLAIN water softener salt (no iron removers or water softener conditioners) thatis 99.5% pure salt is fine, as is solar salt. The pellets will take longer to dissolve than the solar which are large crystals. Pool salt is smaller crystals which dissolve faster. There is still a need to balance your water. Adding a bag of a chemical mix every monthis NOT going to balance your water. If the mix contains CYA(stabilizer) you levels will continue to go up and eventually you might get algae blooms since high CYA levels require running higher free chlorine levels. Most SWG companies recommend running CYA at 50-80 ppm. You still need to monitor total alkalinity, carbonate hardness (for plaster pools or pools with heaters or grouted tilework--moot point for vinyl and fiberglass), pH, and free and combinde chlorine levels. Dont rely on test strips, they are notoriously inaccurate. Get a drop based test kit. Cheap ones are available at Walmart that will test all 5 of the above parameters but the Taylor K-2005 (good) or K-2006 (best choice) are much more accurate. For pH control you need Muriatic acid (dry acid is OK but if you look at the chemistry of generating chlorine HCL [muriatic acid} is a better choice) for raising pH since SWG's produce sodium hydroxide as a byproduct and you will have a constant upward drift in pH. Adjust the pH once it drifts above 7.8. In the rare event that you need to raise pH either Sodium Carbonate (commen washing soda from the grocery store--exactly the same thing as pH increaser) or Borax from the grocery store will do it with Borax being a better choice since it introduces a borate/boric acid buffer system in addition to the carbonate/carbonic acid buffer system that is in your pool which can "gas off' and affect your total alkalinity readings. To adjust total alkalinity you need Sodium Hydrogen Carbonate which is also called Sodium Bicarbonate. They are the same chemical. You can buy the industrial grade at a pool store or the much purer USP grade for less money at the grocery store under the name of "Baking Soda" . Aim for total Alkalinity between 80-120 ppm. Calcium levels are important for plaster pools. Most sources recommend levels between 200-400 ppm. Not much of an issue for fiberglass or vinyl unless you have a heater, grouted tile work, very hard, or very soft water and then you might need to make adjustments. Ideally you should check your Saturation Index or Hamilton Index to see if you water is balanced. There is still a lot of debate about whether the Saturation Index is a useful measurement for pools since it was designed for closed boiler systems to help prevent scaling and corrosion. Free chlorine levels should be checked at least weekly as should pH and if you are running 50-80 ppm CYA should be about 2 or 3 ppm with combined chlorine < .5 ppm. If combined chlorine is higher than that set your SWG to superchlorinate OR you could shock with Sodium Hypochlorite which is available in strennths from 5.25 % to 12 % or higher. Only difference is price and how much you need to use for a given level of free chlorine (shock level is usually 15 ppm or higher depending on your CYA levels and needs to be maintained at that level for about 24 hours). Here is a tip 5.25% AND 6% Sodium Hypochlorite are available at the grocery store and are called Regular Unscented Chlorine Bleach (5.25%) and Ultra Unscented Chlorine Bleach(6%). At your friendly neighborhood pool store you will usually find liquid chorine (6% Sodium Hypochlorite) and liquid shock (12% sodium hypochlorite). Compare prices, it's interesting. Also be aware that the stronger the concentration of sodium hypochlorite in the solution the faster it losses it's strength so that bottle of 12% liquid shock that you bought 2 months ago might only be 6% now !

Do you need to add anything else to you pool with a SWG--maybe. If your fill water has metals you might need a seqesterant. Dp you need to add Algicide? Possibly, but if you balance your water and run your free chloine levels at 2-3 ppm and make sure your CYA levels stay between 50-80 ppm most likely not!

How about clarifiers, flocs, water "optimizers" , enzymes,etc.? IF you follow the above recommendations and keep your water balanced and your filter and pool clean they probably are not necessary but if you like to $pend money go ahead!

Once again I say "Knowledge is power and it can save you a lot of money!"

Waterbear, I see you are a subscriber to the "Pool Solutions" methodology.

[waterbear]

The other statement that you made about test strips not being accurate is not correct. Test strips are as accurate as any DPD or OTO test and in fact they use the same reagents to get their readings. Test strips do have a shelf life as do liquid test reagents.

There is no debate that I am aware of as to wether Saturation index is important on pool water. Saturation index is an accepted measure to determine if water is corrosive or scale forming and we use this calculation daily.

I would recommend the use of algacides to prevent algae from growing in a pool as there are forms of algae that can grow in water with a free chlorine level at 3ppm. CYA does not effect the activity of your chlorine. If you are refering to chlorine lock that theory has been proven to be false.

As far as test strips go they use usually syringaldazine and not OTO or DPD for testing free chlorine. An FAS-DPD tritration can have a precision to .2ppm. In fact, Aqua-check (one of the largest manufacturers of test strips had an FAS-DPD kit also! Just look at your average 5 way test strip and compare it to the accuracy you can get from even a cheap drop based kit and then tell me they are just as accurate! The tests for Alkalinity, CYA, pH, and Hardness don't even come close! At best they are good for a quick check to see if any parameter are out of whack and then a drop based kit can be used to determine just how out of whack.

If you do some reasearch on the Langelier Saturation index you will find it was deveped to predict scaling and corrosion in closed boiler systems. A swimming pool is an open system and Langelier himself doubted that it would be useful...certainly it is a good guide but should not be taken as gospel. There is also the Hamilton Index that was developed by the pool and spa industry that has been in use for many years now that seems to produce good results. Perhaps it would be wise to check both of them.

As far as CYA levels and algae bloom. The higher the CYA levels the less free chlorine is available as a sanitizer...it is a simple chemical equilibrium equation! It has been shown that high stablizer levels will result in lower ORP readings indicating that the oxidation potential of the water has been decreased. It seems that the ones in the industry that promote the "chlorine lock is a myth" are the manufactures of stablized dichlor and trichlor!

I have presented the chemisty to support my statements and it is easily checked out. If you can back up your statements with chemical facts and not just marketing hype I would love to hear it!

[waterbear]

Waterbear, I see you are a subscriber to the "Pool Solutions" methodology.

I have a background in chemistry and pool water chemistry is nothing mysterious. Lets just look at my example of alkalinity increaser, Most pool store brands list the ingredient as sodium hydrogen carbonate. Why don't you try looking up this chemical and see if it has any other names. You will find that is is also called sodium bicarbonate and can be had for less money in the USP grade which is food and pharmaceutical grade at the grocery store under the name of baking soda! Ditto for ph increasere sodium carbonate which is also called Sal Soda or washing soda. Sodium Hypochlorite is Sodium Hypochlorite is Sodium Hypochlorite whether it is labeled laundry bleach or liquid shock. The only difference is the concentration. If it is more concentrated you need less, if less concentated you need more.

Nothing to do with "Pool Solutions Methodology" as you put it. Just basic chemisty!

[sharkman009]

As far as test strips go they use usually syringaldazine and not OTO or DPD for testing free chlorine. An FAS-DPD tritration can have a precision to .2ppm. In fact, Aqua-check (one of the largest manufacturers of test strips had an FAS-DPD kit also! Just look at your average 5 way test strip and compare it to the accuracy you can get from even a cheap drop based kit and then tell me they are just as accurate! The tests for Alkalinity, CYA, pH, and Hardness don't even come close! At best they are good for a quick check to see if any parameter are out of whack and then a drop based kit can be used to determine just how out of whack.

If you do some reasearch on the Langelier Saturation index you will find it was deveped to predict scaling and corrosion in closed boiler systems. A swimming pool is an open system and Langelier himself doubted that it would be useful...certainly it is a good guide but should not be taken as gospel. There is also the Hamilton Index that was developed by the pool and spa industry that has been in use for many years now that seems to produce good results. Perhaps it would be wise to check both of them.

As far as CYA levels and algae bloom. The higher the CYA levels the less free chlorine is available as a sanitizer...it is a simple chemical equilibrium equation! It has been shown that high stablizer levels will result in lower ORP readings indicating that the oxidation potential of the water has been decreased. It seems that the ones in the industry that promote the "chlorine lock is a myth" are the manufactures of stablized dichlor and trichlor!

I have presented the chemisty to support my statements and it is easily checked out. If you can back up your statements with chemical facts and not just marketing hype I would love to hear it!

So are you telling me That the Langelier Saturation index is not a way to determine if water is scale forming or corrosive? I would be very interested in any information that you could point me to about Langelier and the possibility that those calculations may not be useful.

You have not presented the chemistry to prove your point on CYA. It has been proven that in cases that you describe that it was not the CYA levels that reduced ORP but the Total Dissolved solids that reduced ORP.

[waterbear]

So are you telling me That the Langelier Saturation index is not a way to determine if water is scale forming or corrosive? I would be very interested in any information that you could point me to about Langelier and the possibility that those calculations may not be useful.

You have not presented the chemistry to prove your point on CYA. It has been proven that in cases that you describe that it was not the CYA levels that reduced ORP but the Total Dissolved solids that reduced ORP.

I didn't say that the Langeleir Saturation Index was not useful but it was designed for a closed system and a pool is an open system. As a general guide it can be useful but it should not be taken for gospel. If you look at the formula as it is applied to pools it is :

SI=pH+TF+logCH=LogALK-constant

the logs of the CH and ALK readings are very small in comparison to the acutal readings-- rather large changes in these readings only make small changes in their corresponding index.. pH is the main variable that will have the greatest effect on the result since the actual value is used in the calculation. Temperature is the next variable to affect the result since the TF(temperature factor) is the second largest changing variable for a change in the actual measurement (changing .1 for every approx. 5-10 degrees temperature change) .

There is also some debate as to whether the ALK reading should be corrected for CYA. Once again, if the correction is made and the log of the reading is done to give the alkalinity factor it does not have a great impact on the result. pH seems to be the main thing that needs monitoring as long as the other parameters are kept withing recommend ranges (Alk 80-120, CH 200-400 for plaster, not that much of an issue for vinyl and fiberglass) Acidic water will be corrosive and alkaline water will be more scale inducing. Scaling potential will increase with temperature. As a general guideline SI has some merit but if the water is within accepted ranges pH would be the factor to watch in keeping the water balanced since small changes on pH wil have the greatest impact on whether the water is scale forming or corrosive. Sort of commen sense when you look at it.

AS far as TDS just look at any pool with a SWG with a salt level between 3200-6000 ppm. The salt level will measure as the main part of the TDS(my pool had a TDS of 4000 last time it was checked about a month ago and a salt reading of 3300 ppm) and yet ORP readings are viable in such a pool to measure sanitizer levels. In fact Autopilot includes one in their new PoolPilot Total Control system for just that purpose. Salt (NaCl) is neither an oxidizer nor and reducing agent and will not have any effect on ORP readings to speak of but will have a great imact on TDS readings. Granted high levels of CYA will show an equivalent increase in the levels of TDS but is is enough to account for the lowered redox potential of the water. You have to undersand just what ORP is measuring--the ability of the water of oxidize. CYA by it's nature of stablizing chlorine reduces it's ability as an oxidizing agent. If you look at strong oxidizing agents they tend to be unstable and reactive (chlorine, ozone, hydrogen peroxide, to name a few). Look at the self life of sodium hypolchlorite solution compared to dichlor or trichlor. ORP measurements are also used in Salt water aquariums to monitor the redox pontential of the water and the TDS in sea water is MUCH higher than would be found in any pool. TDS of 35,000 ppm is considered standard seawater, in fact. Standard ORP readings are usually abaout 400 mv in a saltwater aquarium and you must realize that this is not supposed to be a sterile system but is a living ecosystem. The accepted ORP reading for a pool is 650mv. pH (our old friend again!) will have more effect on ORP readings in a pool than TDS because at lower pH there is more hypochlorous acid and and higer pH more hypochlorite ions present. It is a well known fact that chlorine is a more effective sanitizer at the lower end of the accepted pH range for pools. Adding CYA to this system once again reduces the amount of hypochlorous acid available in the water as the chlorine forms stable compounds with the CYA and therefore lowers the redox potential of the water.

Sorry for all the chemisty. I tried to dilute it down. (stablize it? )

[sharkman009]

I didn't say that the Langeleir Saturation Index was not useful but it was designed for a closed system and a pool is an open system. As a general guide it can be useful but it should not be taken for gospel. If you look at the formula as it is applied to pools it is :

SI=pH+TF+logCH=LogALK-constant

the logs of the CH and ALK readings are very small in comparison to the acutal readings-- rather large changes in these readings only make small changes in their corresponding index.. pH is the main variable that will have the greatest effect on the result since the actual value is used in the calculation. Temperature is the next variable to affect the result since the TF(temperature factor) is the second largest changing variable for a change in the actual measurement (changing .1 for every approx. 5-10 degrees temperature change) .

There is also some debate as to whether the ALK reading should be corrected for CYA. Once again, if the correction is made and the log of the reading is done to give the alkalinity factor it does not have a great impact on the result. pH seems to be the main thing that needs monitoring as long as the other parameters are kept withing recommend ranges (Alk 80-120, CH 200-400 for plaster, not that much of an issue for vinyl and fiberglass) Acidic water will be corrosive and alkaline water will be more scale inducing. Scaling potential will increase with temperature. As a general guideline SI has some merit but if the water is within accepted ranges pH would be the factor to watch in keeping the water balanced since small changes on pH wil have the greatest impact on whether the water is scale forming or corrosive. Sort of commen sense when you look at it.

sharkman009

Ok first let me say dont take this the wrong way as I discuss this with you as I am open to the possibility that you may be able to teach me something that I did not know.

However everything that I have been taught would call into question some of the things that you have said.

First let me address the saturation index as you said ph is a major factor as long as everything else is in acceptable ranges. The key words are if everything is in acceptable ranges and each one of those items is an important factor in determining what the condition of the water is and it is possible to have one number out of range and have it compensated with another and still be within -.5 -.5 range.

Nobody reffered yto saturation index as the holly grail but it is an important factor that can not be left out.

I realize that it was originally designed for a pressurized system but as you know water in an unpressurized environment has more of a tendency to drift to one side or another. In other words if the saturation index is high in an unpressurized environment it will precipitate scale faster than a pressurized sytem so if it will work for a boiler system it will work for a pool.

AS far as TDS just look at any pool with a SWG with a salt level between 3200-6000 ppm. The salt level will measure as the main part of the TDS(my pool had a TDS of 4000 last time it was checked about a month ago and a salt reading of 3300 ppm) and yet ORP readings are viable in such a pool to measure sanitizer levels. In fact Autopilot includes one in their new PoolPilot Total Control system for just that purpose. Salt (NaCl) is neither an oxidizer nor and reducing agent and will not have any effect on ORP readings to speak of but will have a great imact on TDS readings. Granted high levels of CYA will show an equivalent increase in the levels of TDS but is is enough to account for the lowered redox potential of the water. You have to undersand just what ORP is measuring--the ability of the water of oxidize. CYA by it's nature of stablizing chlorine reduces it's ability as an oxidizing agent. If you look at strong oxidizing agents they tend to be unstable and reactive (chlorine, ozone, hydrogen peroxide, to name a few). Look at the self life of sodium hypolchlorite solution compared to dichlor or trichlor. ORP measurements are also used in Salt water aquariums to monitor the redox pontential of the water and the TDS in sea water is MUCH higher than would be found in any pool. TDS of 35,000 ppm is considered standard seawater, in fact. Standard ORP readings are usually abaout 400 mv in a saltwater aquarium and you must realize that this is not supposed to be a sterile system but is a living ecosystem. The accepted ORP reading for a pool is 650mv. pH (our old friend again!) will have more effect on ORP readings in a pool than TDS because at lower pH there is more hypochlorous acid and and higer pH more hypochlorite ions present. It is a well known fact that chlorine is a more effective sanitizer at the lower end of the accepted pH range for pools. Adding CYA to this system once again reduces the amount of hypochlorous acid available in the water as the chlorine forms stable compounds with the CYA and therefore lowers the redox potential of the water.

Sorry for all the chemisty. I tried to dilute it down. (stablize it? )

On the issue with chlorine lock I will look up the study but the first one that I recall was done in the late 60s called the myth of chlorine lock. I will have to look up the study to get you the doctors name that did the study but there are many that have been done that have proven that CYA does not lock chlorine in or make it less active. In fact it has been proven that chlorine is very active in environments with CYA levels as high as 500ppm.

When it comes to ORP or Oxidation reduction potential. I believe you stated it as the waters ability to oxidize and that would be incorrect. It is the measure of the oxizidizing capacity present in millivolts.Oxididizers accept electrons. Reducers lose electrons. Examples of reducers are sodium thiosulfate and sodium bisulfite. An increase in oxidation will result in a decrease in reduction and the other way around.

Since most disinfectants are oxidizers, they provide a positive ORP reading that increases as the oxidizer concentration increases. Orp is an indirect way to measure disinfectant level and does not measure disinfectant directly.

ORP and disinfectant concentration do not have a linear relationship. At low chlorine concentration, ORP increases quickly with a small change in chlorine concentration. At high chlorine concentration, ORP increases slowly with a change in chlorine concentration.

With increased TDS it is common sense that chlorine would take longer to do its job. The more particulants present the longer it will take the sanitizer to reach any bacteria present.

[waterbear]

On the issue with chlorine lock I will look up the study but the first one that I recall was done in the late 60s called the myth of chlorine lock. I will have to look up the study to get you the doctors name that did the study but there are many that have been done that have proven that CYA does not lock chlorine in or make it less active. In fact it has been proven that chlorine is very active in environments with CYA levels as high as 500ppm.

but not as active as at lower levels. and by whom was it proven. would like to read that.

When it comes to ORP or Oxidation reduction potential. I believe you stated it as the waters ability to oxidize and that would be incorrect.

I underestimated your knowlede of chemistry and was trying to simplfy. I appologize.

It is the measure of the oxizidizing capacity present in millivolts.Oxididizers accept electrons. Reducers lose electrons. Examples of reducers are sodium thiosulfate and sodium bisulfite. An increase in oxidation will result in a decrease in reduction and the other way around.

Since most disinfectants are oxidizers, they provide a positive ORP reading that increases as the oxidizer concentration increases.

But not all oxidizers are disinfectants--ozone, hydrogen peroxide and permonosulfate being examples. They will increase the redox potential without acting as a sanitizer.

Orp is an indirect way to measure disinfectant level and does not measure disinfectant directly.

ORP and disinfectant concentration do not have a linear relationship. At low chlorine concentration, ORP increases quickly with a small change in chlorine concentration. At high chlorine concentration, ORP increases slowly with a change in chlorine concentration.

With increased TDS it is common sense that chlorine would take longer to do its job. The more particulants present the longer it will take the sanitizer to reach any bacteria present.

This is completely wrong TDS does NOT measure particulants in the water, it is a measure of ionic strength of everything dissolved in the water and is usually done with a meter that measures conductivity. Unless something dissolved in the water is interfering with chlorine's abilty to act as an oxidizer (such as CYA or high levels of -OH ions from high pH which will push the equilibium of hypochlorius acid/hypochlorite ion to the hypochoite ion side of the equation) TDS will have NO effect on how long chlorine takes to sanitize. NaCl concentrations can be as high as 6000ppm and are in some pools with SWG's and free chlorine levels of as low as 1ppm can effectively sanitize the water and give the required ORP readings of 650 mv or higher.

It's late at night now so I will keep my reply brief but I am enjoying this discourse. As far as CYA and chlorine lock I refer you to http://www.ppoa.org/pdfs/PrP_Cyanurics%20-%20Benefactor%20or%20Bomb.pdf for an intersting discussion of CYA, ORP, and TDS. As far as SI goes there are 3 that are in use with swimming pools--Langelier LI = pH - pHs), Ryznar (RSI = 2pHs - pH) which is more hypothetical but more applicable to flowing systems, and Hamilton(no idea of the fomula or if there even is one) which was develped by the pool industry and is supported by, I believe, over 10 years empirical evidence. The point I am trying to make is that balanced water with one calculaton will be unbalanced with a different one. pH seems to be the factor in all three that has the most effect. In fact, the Hamilton Index was designed for running pools at higher pH--7.8 to 8.0. If the pH is high Cl levels should probably be run a bit higher since more hypochlorite ion is pesent vs. hypochlorus acid. Bottom line, pool chemistry is not an exact science. Even the selection of 650 mv for ORP readings is arbitrary.

The point I am trying to make about TDS is that you can load a pool down with NaCl, which is neither an oxidizing agent nor a reducing agent, until your TDS is over 6000ppm and run very low Cl levels to reach that reading of 650 mv.