chem geek
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Posts posted by chem geek
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I was going to suggest bromine since you can use bromine tabs in a floating feeder to dose when you are not there. However, you are right that bromine smells different than chlorine and some people don't like it. If you add oxidizer after your soak, then you can maintain a low 2-4 ppm bromine level in between soaks which is roughly equivalent to 1-2 ppm chlorine so when you start your soak you won't have too much bromine. Some people try to use tabs only and therefore have a high enough bromine level to handle their bather load, but that means a higher level during the soak which can be annoying. So you could try this in a better way with a low bromine level in between soaks so you start out low. If you have an ozonator, then it will make bromine from the bromide bank which means you may not need to use bromine tabs, but it can be tricky to have the right-sized bromide bank to not underdose or overdose the bromine level.
As for Nature2 with silver ions and using MPS as the oxidizer (and disinfectant when used with the silver ions), it will last longer than chlorine if you dose with excess, but it still does get used up. So perhaps you could dose enough to last for a week, but probably not for too much longer. As for the water getting cloudy, you can mitigate that by using chlorine on occasion, say once every week or two. The main benefit with this method is that it is largely non-halogen so works for people who for whatever reason want no chlorine or bromine during their soak. As I wrote, the MPS does last longer than chlorine after bather load is handled, but probably not enough for an extended vacation. If you have an ozonator, the ozone won't react with MPS the way it does with chlorine.
An SWCG is a good option if one uses CYA in the water to moderate chlorine's strength. As for the warranty, yes the issue is corrosion, but again the main reason for such corrosion problems is that the SWCG is often used without CYA in the water which makes the chlorine WAY too strong so more corrosive especially combined with the higher salt level. Nevertheless, even with CYA in the water and careful setting of the SWCG to not get the FC too high, the higher salt level is more corrosive especially to inferior materials such as lower quality metals (e.g. zinc). The salt level for the Technichlor is around 2000 ppm, not the 3000 ppm typically used in swimming pools. If your spa has decent stainless steel (at least 304 if not 316 or 316L) and has a cupro-nickel or titanium heat exchanger, then it should not have any problems with the higher salt level.
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1) You can get the Taylor K-2006 at TFTestkits.net.
2) If you have a high bather load, then an ozonator will help make the water last longer. MPS isn't as great an oxidizer as chlorine so will have more trouble keeping the water clear. You could periodically shock with chlorine, but having an ozonator may let you avoid that. As for how long between water changes, this depends on the system you use, but I'd figure that with no ozonator it would be roughly (1/9) x (Spa Size in Gallons) / (# of Person-Hours Per Day) while with an ozonator you might get close to double that.
3) See answer for question #2 above. For high bather load, an ozonator is worth it.
4) Use Ahh-Some both initially after you get your spa and just before you change the water.
5) Borates can be used with any of the systems. It's most easily added from boric acid.
I agree with the previous posts regarding not using bromine since any allergy or reaction to chlorine is likely to be against all halogens. You basically have two choices. One is to use Nature2 (silver ions) with MPS. The other is to use Baquacil/biguanide/PHMB. The former is less expensive than the latter. Another option would be to use chlorine for maintaining the spa but to dechlorinate prior to a soak, probably using hydrogen peroxide to do so since it has the least side effects. You'd then add chlorine again right after your soak (when she's out of the spa and most likely you'd be adding it so she doesn't smell any resulting chloramines). This is obviously a riskier approach, but if it's just the two of you soaking then the risk is very low. Bacteria take 15-60 minutes for every doubling of population under ideal conditions and as for person-to-person transmission of disease, you're likely to be doing that to some extent anyway outside of the tub.
So does your girlfriend use a whole-house water filter to remove chlorine and chloramines from the water or a shower filter? If not, then her reaction may not be with chlorine.
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A negative CSI is not a problem in an acrylic spa since there is no plaster/grout with calcium carbonate to protect. As for preventing metal corrosion, pH is the primary factor there (i.e. not having pH get low) as well as not getting the chlorine level too high but with CYA in the water that would be hard to do since the active chlorine level is relatively low.
Because of the risk of calcium carbonate scaling in a hot spa especially in the heat exchanger it is better to have the CSI be less than 0. So a maximum CH of 150 ppm is reasonable for that given the other parameters including the pH that can get towards 8.0.
The ozonator is generating air bubbles that aerate the water so that contributes to the pH rise though with a spa cover there shouldn't be too much carbon dioxide outgassing. It's probably more due to your frequent usage. As to why it occurs more as the water ages, I don't know why that would be. Are you using Dichlor for a day once per month to keep the CYA level up? Chlorine will slowly oxidize CYA at around 5 ppm per month.
If you are soaking for 30 minutes with 1-2 people 5-6 times per week then that's (30/60)*1.5*5.5/7 = 0.59 person-hours per day so the Water Replacement Interval (WRI) with the Dichlor-then-bleach method would be around (2/9)*(400 gallons)/(0.59 person-hours per day) = 150 days or around 5 months. With the ozonator I would think you could get to that long before needing a water change. The ozonator does consume chlorine in between soaks but it should let you use less chlorine after each soak so on balance with your heavier usage it should be letting you use less chlorine.
Have you noticed the TA rising over time? It is odd for the pH rise to occur more quickly over time without something else changing to make that happen. Maybe soap or oils from your skin or swimsuits accumulate some and may change the surface tension of the water or other surface characteristics to have more outgassing, but with the TA at 50 ppm and CYA at 30 ppm carbon dioxide outgassing would stop completely at a pH of 8.0 and should slow down considerably by 7.8. Note that carbon dioxide outgassing is faster not only at higher TA but at lower pH so if you lower you pH a lot you actually increase the rate of pH rise. Also, with your frequent acid addition, you should be noticing the TA drop over time so have you been adding baking soda to compensate for that?
Did you change your brand of bleach? Some brands have more excess lye in them and that would cause the pH to rise. Clorox bleach should have the least amount of excess lye.
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Bromine tabs add bromine to the water right away. You don't need sodium bromide initially to get bromine in that case. The purpose of the bromide bank is that you can add an oxidizer such as chlorine or non-chlorine shock (MPS) to create more bromine quickly, especially after a soak.
Usually the TA would only drop by adding something net acidic. SpaBoss Spa Shock is MPS and that is an acidic product unless they added something else to it to make it more pH neutral (I couldn't find an MSDS for it). So that probably explains why the TA dropped over time. When you were using bleach as your oxidizer, the TA should stay about the same or very slowly rise until you add acid for controlling pH. Basically acid is what lowers TA, whether that be pure acid or an acidic product such as MPS.
As for sodium bromide, you can get it in solution in this product in Canada or you can get a granular mixture of sodium bromide and Dichlor chlorine in this product which is typically called brominating granules, but that will produce bromine. So the first product would be better to just create a bromide bank without generating bromine right away. OR you could just use the latter product which over time will build up a bromide bank. As I wrote above, the tabs also increase the bromide bank since the bromine when it is used converts to bromide.
Yes, to raise TA you can just use baking soda. If you look at the ingredients of Alka-Rise or Alkalinity Up products, they are just sodium bicarbonate (or sodium hydrogen carbonate) which is the same as baking soda.
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Hasa also has The pH Adjuster but that uses dry acid which would not be good for plaster pools since it would build up sulfates.
The Hasa products are inexpensive and you get what you pay for. Peristaltic pumps are more reliable and yes they can handle either chlorinating liquid / bleach or acid (separately, of course). As for brands, I suggest you look at the Chemical Automation forum. I'm not an expert in that area.
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You could accelerate the TA lowering process by lowering the pH close to 7.0 and aerating the water and adding acid whenever the pH rises some. This process drives out carbon dioxide from the water faster since that rate is increased at lower pH and with more aeration.
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Your particular pH Up product you refer to is the same as the sodium bicarbonate you are getting for your well water but most pH Up products are sodium carbonate. The sodium bicarbonate will tend to raise the Total Alkalinity (TA) more than the pH and you will usually fight with more pH rise as a result. You also risk calcium carbonate scaling in your spa if your water is hard (high in Calcium Hardness) and your TA is high.
If you have enough aeration of the water to prevent your pH from falling, then you could indeed use the sodium bicarbonate to maintain the TA level that would otherwise drop from use of net acidic chemicals such as Dichlor where for every 10 ppm FC it adds it also lowers the TA by 3.5 ppm after chlorine usage/consumption.
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An SWCG is a saltwater chlorine generator. You increase the sodium chloride salt level in your pool, usually to around 3000 ppm, and add the SWCG inline in your plumbing in the pump room and it will generate chlorine from the salt.
The other automation approach is to use a peristaltic pump and a tank of sodium hypochlorite (chlorinating liquid or bleach) for dosing chlorine. There is also The Liquidator from Hasa.
Cal-Hypo is normally granular so would not work for slower dosing. There are special Cal-Hypo pucks with special feeders but to put the Cal-Hypo into pucks requires binder chemicals that leave a residue so this is not commonly used except in some industrial or large swimming pool applications (see Accu-Tab). Also, Cal-Hypo will increase Calcium Hardness (CH) though that's not as bad as increasing CYA since your CH can go up more than CYA before it becomes a problem.
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The same question has been asked and is being answered in this forum.
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You have to change the water to go from bromine to chlorine; the other way around from chlorine to bromine can be done without changing the water.
The best test kit is the Taylor K-2006. It will work for bromine as well (though the 2106 is more commonly used for that), but is tops for chlorine. However, that kit is VERY expensive in Canada. The K-2005 will be less expensive but will only have a DPD chlorine test so won't read above 10 ppm and won't be as accurate, but will still be better than your test strips.
For Dichlor-then-bleach you should just need to get Dichlor, usually called chlorinating granules, and unscented regular bleach such as Clorox bleach (8.25%), and acid (dry acid which is sodium bisulfate is OK), and boric acid you can get from Duda Diesel where for 315 gallons to get to 50 ppm Borates would take 12 ounces weight (around 13-1/2 fluid ounces volume). You can use PoolMath to calculate dosages.
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Forget the part about adding MPS. For the Dichlor-then-bleach method that should not be necessary. I didn't write that article and can't edit it to correct it.
If you soak every day or two then the Dichlor-then-bleach method isn't a lot of work since you just add chlorine after every soak. If you don't soak that often, then it's more of a pain because you need to add chlorine in between soaks. Also, if you have an ozonator and don't use the spa every day, it's more work since ozone reacts with chlorine using both up.
Bromine is generally easier, especially if you don't soak frequently, because bromine tabs in a floating feeder can be used to provide a background dose of bromine in between soaks. If you have an ozonator, then starting a bromide bank (adding sodium bromide) when you change the water then has ozone generate bromine from that bromide. You still usually need to add an oxidizer after each soak if you soak infrequently, but you can use chlorine for that (i.e. you don't need to use MPS). You can see this post on the 3-step bromine method -- 1) add sodium bromide after changing the water, 2) use bromine tabs in a floating dispenser, 3) add an oxidizer (e.g. chlorine) after each soak.
The only issue with bromine is that it doesn't keep the water as clear as with chlorine, but if you use chlorine as your oxidizer after each soak it should be OK. Worst case, you can shock with chlorine on occasion if needed.
I don't know what Brom-Aid is. Does it have a list of ingredients or a manufacturer name on it? I'm not sure why your wife didn't like brominating concentrate since that's generally a combination of sodium bromide with chlorine so after you build up bromide (or add it initially) it makes bromine. Perhaps you should try the 3-step method I described/linked above.
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These questions were posted in this thread in another forum and answered there.
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Since it's well water, the CH and TA may be high and with the water now exposed to air the outgassing of carbon dioxide from the high TA has the pH rise. That combination causes calcium carbonate scaling and might produce flakes of it. However, usually those flakes will be hard and will not dissolve as easily as you describe. If you collect some and add some acid to them and they fizz, then they are likely calcium carbonate.
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You posted the same questions in another forum and I answered them there.
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Wow, that's an extraordinarily high bather load due to soaking twice every day with 2 people and in such a small spa.
So you are doing things right to start out with the Dichlor-then-bleach method. When you are lowering the TA by adding acid, if the pH is high stop using the jets. Aeration will raise the pH faster. If you add some acid now, the pH should drop. And yes, if you start using Dichlor it will slowly lower the TA but as to whether it will lower the pH it depends on the aeration since carbon dioxide outgassing will raise the pH. So I'd try adding pH decreaser to calm spa water and test after a few minutes of circulation mixing (not spa jets). If you get the pH closer to 7.5, then add boric acid which should help slow down the rate of pH rise.
When you have the TA low and a lot of aeration you really need the Borates to help prevent the pH from getting high as quickly. This is especially true in your case because your CH starts out higher so you want to prevent calcium carbonate scaling by keeping the TA low (which you are) and the pH from getting too high (too much above 8.0). The good news is that with such a small spa the amount of chemical like boric acid you need to add is fairly small in quantity so not expensive.
The metal control is just to prevent metal staining from the fill water. Given your high pH, you are at risk for metal staining if the metal level is high enough and with well water that can certainly be the case.
If you've never used Ahh-Some it would be a good idea to do so, if not now then at the next water change (you use it before you dump the water).
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Under ideal conditions, bacteria double in population every 15 to 60 minutes. One bacteria can turn into into 4 billion in 8 hours. In practice, the growth rate is more limited, but it is still very significant as should be obvious from the fact that you can get very sick from eating chicken sitting out on a counter for just one warm day (or less).
When you take a bath and change the water each time, you don't leave any water in the bathtub and most importantly you don't have piping where water gets trapped. When one is talking about a jetted spa, treating it like a bathtub and only changing the water and not doing any disinfection can lead to serious problems as noted in this post where Stacy described how she contracted Legionnaire's Disease at a hotel that did just what you describe changing the water but not maintaining disinfectant (as noted in this link the soft tubs were treated as "drain and fill" and where not chlorinated in spite of their having piping and jets).
In this thread I compiled numerous reports of hot tub itch/rash/lung reported on this forum. Most reports were due to inadequate disinfection letting the disinfectant level go to zero for too long. The use of some "alternatives" was also an issue and the longer-term use of Dichlor (over 2-3 months) also contributed where higher CYA levels made chlorine less effective.
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The pH is rising quickly because the TA is too high. Did it start out high because of your fill water? Is such water from a well?
If you significantly lower your TA by adding acid and aerating, that will help to stabilize the pH. Your TA should not be higher than 80 ppm and if you are using a hypochlorite source of chlorine (e.g. bleach) instead of Dichlor, then it should be even lower, as low as 50 ppm, but you would then also add 50 ppm Borates (from boric acid) for additional pH buffering.
After you get your TA lowered, you should look at minimizing aeration in your spa since that drives off carbon dioxide and causes the pH to rise. Of course, you may use your spa jets when in the spa though if you can control how many jets are on to only those you need, that will help.
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Ahh-Some will help to dislodge lots of material and then you can superchlorinate to disinfect the rest. It will take scooping and multiple water changes.
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This MSDS shows the product to be Oxone which is the triple salt that includes potassium monopersulfate, though it also indicates that the product may contain up to 20% sodium carbonate, most likely to balance the acidity of the Oxone/MPS.
So that would not increase the CYA level. However, if you were to use Leslie's Chlor-Brite, then that is Dichlor that would increase the CYA.
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For every 10 ppm Free Chlorine (FC) added by Dichlor (chlorinating granules), it also increases Cyanuric Acid (CYA) by 9 ppm. This is why we have the Dichlor-then-bleach method that avoids the CYA buildup. You use Dichlor initially until you'e cumulatively added around 33-44 ppm FC which should give you around 30-40 ppm CYA at which point you switch to using bleach. You still use Dichlor about once a month since CYA slowly gets oxidized by chlorine in spas at the rate of around 5 ppm per month.
If you are using bleach, you should initially have some CYA in the water either using pure CYA or using Dichlor. Otherwise the active chlorine level will be too high and can damage equipment, spa covers, oxidize swimsuits skin and hair faster, etc.
Once you are using bleach, the CYA level should not be climbing. Bleach has no CYA nor does non-chlorine shock. Double check your non-chlorine shock to make sure the ingredients don't list Dichlor since some "shock" products are a combination of Dichlor and MPS.
I suspect the pool store testing is wrong. Get your own good test kit -- the Taylor K-2006 -- to know what is truly going on.
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Basically, if you soak regularly then the saltwater chlorine generator isn't very helpful. It's best for those who just soak on the weekends and for those who soak infrequently and have ozonators. It's just about automatic dosing in between soaks so look at it that way in terms of price for convenience.
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When using chlorine, an ozonator only makes sense if you use the spa every day or two because with that higher bather load the ozone will oxidize some of the bather waste so that chlorine doesn't have to. The problem is if your bather load is lighter so that you use the spa only on weekends or with gaps of a few days in between soaks. In that situation, ozone reacts with chlorine (producing chloride and chlorate) so increases chlorine demand in between soaks requiring you to add chlorine every day or two. Without an ozonator, you can usually add chlorine twice a week and be fine and even add it once at a higher level to last the week when on vacation, especially if the water temperature is lowered.
As for a saltwater chlorine generator, there are several people using the ControlOMatic Technichlor and are happy with it. The price is around $220. I don't know about other brands.
Just keep in mind a few things. These generators are NOT automatic in the sense that they don't know when you're soaking so don't know how much chlorine is needed. You set them at a level to maintain a chlorine level in between soaks. Some have "boost" mode but this may be too little or too much for your bather load. You can just add bleach after each soak to handle your bather load and use the saltwater chorine generator to maintain chlorine levels in between soaks. That will work out best when using the spa less frequently and will have the salt cell last a long time.
Note that you MUST add Cyanuric Acid to the spa water or else the active chlorine (hypochlorous acid) level will be far too high. You can do this either by adding pure CYA (which dissolves slowly) or by using Dichlor initially for a while -- roughly 33-44 ppm FC cumulatively added gets you 30-40 ppm CYA. You'll need to use Dichlor for a day a month to add around 5 ppm CYA since chlorine slowly oxidizes it. If you do not use CYA, your hot tub equipment and covers will not last as long and your swimsuits and skin will be oxidized faster and you'll smell more chlorine (i.e. it will outgas more).
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As PreservedSwine noted, half ounce (one tablespoon) per day is too high in between soaks. In 550 gallons that would be 3.8 ppm FC. Is this because you are soaking every day? That would be around 30 person-minutes of soaking with no ozonator or around one person-hour with an ozonator (but these are just rough rules-of-thumb). If you aren't soaking every day, then you should not add that amount in between soaks. If your ozonator is working, then the amount of chlorine you need to add after a soak is significantly less than the basic rule-of-thumb, usually around half the amount compared to no ozonator. Perhaps that is why you are getting too high. You should not be only going by a rule-of-thumb but should actually be measuring the FC level and adding whatever it takes to maintain a low FC residual, usually around 2 ppm in between soaks (not more than 4 ppm) and usually target around 1-2 ppm FC for the start of your next soak. Obviously right after a soak when you add chlorine the FC will spike, but if you are dosing the correct amount the FC should drop fairly quickly so that 24 hours later you are at your background level (2-4 if not soaking right away; 1-2 if you plan to soak the next day)
1/2 teaspoon of Dichlor in 550 gallons is 0.6 ppm FC and the daily loss if it were 25% of 2 ppm would be only 0.5 ppm FC so if your loss is even lower you'd need even less chlorine in between soaks to maintain the FC level. You need to figure this out by testing your FC in between soaks as you have done to figure out your chlorine demand and then just add the amount of chlorine needed to maintain an FC in between soaks -- the FC need not be high and 2 ppm is enough if you maintain it but I wouldn't have it be any higher than 4 ppm. Most people like to start their next soak with 1-2 ppm FC so that they don't notice the chlorine.
So you add a larger amount of chlorine proportional to your bather load right after your soak and then you add rather small amounts of chlorine in between soaks to maintain the FC level. What is confusing is that you measured a rather low 24-hour chlorine demand since with an ozonator that would usually be higher, typically 50% or higher.
Also, if you were going to use the Dichlor-then-bleach method, then you need to keep track of how much Dichlor you are adding. When you've added cumulatively around 33-44 ppm FC, then that's 30-40 ppm CYA and you should switch to using bleach. You then use Dichlor about once a month to keep the CYA up. Note that PreservedSwine mentions another way you can keep the CYA in check which is to use some non-chlorine shock instead of only Dichlor. That too will lower the rate of CYA buildup and let you go longer between water changes. Just note that both Dichlor and non-chlorine shock are net acidic so you'll have to bump up your TA as it drops over time. If you instead used bleach, then that won't happen, but you'll need to manage the pH from rising.
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Yes, that is a low chlorine demand if the ozonator is working. You can add hydrogen peroxide to easily lower chlorine levels. You would need about 11 fluid ounces of 3% hydrogen peroxide (typical concentration for it in a drug store) for 550 gallons to lower the FC by 10 ppm. Basically you can use PoolMath (that's maintained whereas The Pool Calculator no longer is maintained) and put in 6% bleach and that quantity is the same amount of 3% hydrogen peroxide needed to neutralize the FC amount you put in the calculator (i.e. pretend you are increasing FC using 6% bleach, then use that same quantity of 3% hydrogen peroxide to neutralize that amount of FC).
Could it be that you actually have bromide in your water and that the ozonator is making bromine from it? You didn't add any sodium bromide or use any bromine tabs, did you?
Please Help With Low Ta
in Hot Tub Water Chemistry
Posted
Well something doesn't make sense. If you use chlorine to create more bromine from the bromide bank and you don't add other products, the TA will not drop.
A water change is unlikely to fix the problem since it is likely related to some acidic chemical you are adding to the spa. Of course, you can change the water if you want, but you really should figure out what you are adding that drops the TA -- it HAS to be something acidic. MPS is quite acidic. Bleach is not.