Plain And Simple, What Is Better Chlorine Or Bromine

[newspaguy]

As most new spa owners I have been spending way more time than I should researching water chemistry and different methods of keeping the water sanitary. Ive gotten alot of info from chem geek and his bleach method seems brilliant, however, Im one of those owners that just will not want to put the time in to deal with the fluctuating ph chem geek warns about with that method.

Ive been using the Nature2 with Dichlor after each use and an MPS shock weekly. However, after reading several posts on here, Im beginning to think Id be doing the same thing with only Dichlor and could do with out the $30 nature 2 cartridge as Im not sure its offering any benefit since Im using Dichlor.

Ill be doing a water change before the weather gets really cold (Wisconsin) and then I will have to live with the same water for probably the next 4 months due to the consistant cold we get here.

So will someone break it down for me to the simplest terms. What is the better method to use, Chlorine(dichlor) or Bromine(with a feeder) as far as ease of use, water quality maintenance, and bather comfort (keeping in mind Ill have to maintain the water for several months without the ability to refill due to freezing temps). This is for a smaller 240 gal tub.

Thank you for any input you much more experienced uses can offer

Geoff

[Peter Smit]

As most new spa owners I have been spending way more time than I should researching water chemistry and different methods of keeping the water sanitary.

Geoff

Same for me, much time had to be invested . I have concluded that Bromine is the easy way, espacially as my wife has to do most of the maintenance. I am very new to his, so bare with me... but I have started to make a guideline so my wife can do the maintenance (see below). It is a work in progress.

_________________________________________________________

Dummies proof... guideline for Hot Tub (with ozonator and approx 250 Gallons) using Bromine

Watersource: CH 80ppm / ALK: 80ppm / PH 6.8

To Buy:

* CH/Alk/Ph/Brom teststrips

* Calcium Chloride (CH increaser)

* PH+

* Sodium Bromide

* Bromine tablets and floating dispenser

* Filter cleaner (chemical)

* Foam way

* Oxi Shock

* ........... (Spa water clarifier. Collects small particles into large masses to be removed by the filter.)

_________________________________________

* 1 spare set of filters

* 1 small electronic Weighing scale (2- 5 gram increments)

* 1 large airtight container for all chemicals

* 1 10L bucket to disolve each chemical (individually!) and a stirring stick

Starting up from empty

* Check if filters are in (bottom right)

* Check if emptying valve at the back is closed

* Fill with water till halfway down the overflow in right bottom corner putting the hose into the filter compartment (preventing airpocket problems)

* Put electricity on and check if jets are working, if not bleed pumps DO NOT RUN FOR MORE THAN 2 MIN IF NO WATER FROM JETS!

* Set to STD (Standard) (warming up to 40 degrees Celcius will take around 1 hour per 3 degrees Celcius).

* Add 20 gram of Calcium Hardness increaser

* Follow: "Getting the right waterbalance"

* Add ¼ tablet of Bromine info filter compartment

* Put floater in with (4) tablets of Bromine and valve opened to 2 gaps.

* Wait 3-5 minutes and put jets to "low" and close cover and straps!

* Keep STD mode (and run for 8-24 hours)

* When Water at 40 degress Celcius follow: "Getting the right waterbalance" again

* Add 50ml of antifoam

_________________________________________

Before using the Hot Tub

An hour or longer before follow guideline "Getting the right waterbalance" and set menu to STD

Check waterlevel (fill to about half way up the top skimmer, if nessecary)

After using the Hot Tub:

1: Set Hot Tub to: ECO mode (or to SLP mode when not using it in the next 48 hours--> temp 10 degrees below set point)

2: Add blue/white floater to the water and check if at least 1/2 tablet of bromine and valve open 2-3 vents

3: Put Diverters in middle position

4: Remove headrests when not using hot tub for 48 hours or longer (will deteriorate due do Ozone and chemicals)

5: Add insulation blanket to cover the water

6: Add Cover and strap it

"Getting the right waterbalance"

* Fold back cover

* Press "JETS" button twice to high speed

* Take 1 strip out of container (keep everything dry) and close it

* Put measuring stick in (30cm deep) and keep it horizontal after taking it out

* Check color against levels on the back of container and write down the 4 levels (CH/Alk/PH/Bromine)

ADDING CHEMICALS: NEVER MIX! ALWAYS FILL 8L (3 GALLON) BUCKET WITH WARM WATER FROM HOT TUB, STIR TILL DISSOLVED AND POOR INTO FILTER COMPARTMENT. DO THIS WITH EACH CHEMICAL INDIVIDUALLY AND WAIT 5-10MIN BEFORE ADDING THE NEXT CHEMICAL!

Calcium Hardness (CH) (ideal level 100-200 ppm)

If to low add CH+ (5gram per 10ppm for 250 gallon)

If to high add CH- (5gram per 10ppm for 250 gallon)

Alkalinity (ideal level 80 and 120)

ALK LOW and PH LOW: follow directions for PH

ALK LOW ad PH high: ???

ALK HIGH and PH HIGH: follow directions for PH

ALK HIGH: and PH low: slowly add PH+ (add 10gr per 2 hours and retest)

PH (add PH+-) (Perfect: 7.5; ideal range is 7.4 to 7.6, acceptable 7.2 to 7.8).

For each 0.1 point below 7.5 add 2.5 gram of PH+

HIGH: For each 0.1 point above 7.5 add 2.5 gram of PH-

Bromine (Ideal 3-4) (when filling the Hot Tub from empty the Bromine will be "0").

LOW: Add a few gram of Bromine into filter compartment, (for next time adjust Bromide Floater to 1 more gap)

HIGH: Run jets and air on high power in the open air (sun) for 10min per ppm to high and retest. If still high, continue running and/or remove 2cm of water for every point to high and refill. Do NOT use hot tub when Bromine is above 10ppm!

Wait 60 minutes after all adjustments before retesting.

_____________________________________________________

After each 6 uses (hours x people) (4 person for 30min = 2 uses) or at least every week days:

* Add 20ml of antifoam

* Add .. gram Oxishock (till Bromine is 10) and run jet at full power with open cover for 30min

* Check Alk/PH/Bromine

Every week:

Clean sides with vinager

Check floating dispenser and add Bromine tablets if necessary

Follow directions: "Getting the right waterbalance"

Add 10ml MPS and 5ml extra for each hour (multiplied by number of persons) to a maximum of 50ml

Every 2 weeks

Rinse filter, without using the filter cleaner

Monthly

Change filters, wash the used ones with hose and put overnight in a bucket with ..ml Spa Cartridge Cleaner. Next day rince them thorougly and let them dry and store them for next change

Every 2-3 month empty and refill the Hot Tub

*Choose A or B:

* A: 1 day before, remove bromine floater and do not add chemicals anymore

* B: Run hot tub with: Spa flush or Swirl Away Pipe Cleaner (add ..gr and run for ..min) then -->.

* Cut of power to the Tub.

* Open valve at the back of Hot Tub and let water run. check tube extension to ensure proper draining.

* When empty, add 1/2 cup bleach to 3 gallons (10L) of water and sponge clean the spa shell. Rinse with ample fresh water.

* Change filter (see "Change filter")

Change Filter:

* Remove filter (see picture below) and immediately replace with spare filter!

* Rinse filter thoroughly with hose

* Add ..ml filter cleaner (or just dissolve a dishwashertablet in hot water) to bucket and add enough water so filters are below waterlevel

* Let it stand overnight (or min 8 hours)

* Next day rinse out thoroughly and store to dry

Holliday empty

0: Fully remover cover!!!

1: Turn temparature to low (30degrees or so).

2: Add +-50 grams of OXIshock to the water

3: Run jets at full power in STD mode

4: Wait 2-3 hours!!!

5: Turn Hot tub OFF at breaker in the Summerhouse

6: Open Valve to empty (3-4 hours...)

7: Remove filters and clean them in a bucket with the hose!!! and put filters in summerhouse to dry

8: Empty last bit of water from Hot Tub with bucket

9: Add 1 Bromine tablet to middle of hot tub in the water

10 Add wooden beam, cover and black plastic and secure it!

11: Done

[tony]

As most new spa owners I have been spending way more time than I should researching water chemistry and different methods of keeping the water sanitary. Ive gotten alot of info from chem geek and his bleach method seems brilliant, however, Im one of those owners that just will not want to put the time in to deal with the fluctuating ph chem geek warns about with that method.

Ive been using the Nature2 with Dichlor after each use and an MPS shock weekly. However, after reading several posts on here, Im beginning to think Id be doing the same thing with only Dichlor and could do with out the $30 nature 2 cartridge as Im not sure its offering any benefit since Im using Dichlor.

Ill be doing a water change before the weather gets really cold (Wisconsin) and then I will have to live with the same water for probably the next 4 months due to the consistant cold we get here.

So will someone break it down for me to the simplest terms. What is the better method to use, Chlorine(dichlor) or Bromine(with a feeder) as far as ease of use, water quality maintenance, and bather comfort (keeping in mind Ill have to maintain the water for several months without the ability to refill due to freezing temps). This is for a smaller 240 gal tub.

Thank you for any input you much more experienced uses can offer

Geoff

I have owned my spa for over six years and use my spa almost daily. I soak in the morning so it is part of my daily routine. I used dichlor with N2 and ozone for years. I have shocked with both MPS and chlorine. IMO, if you use your spa on a very regular basis as I do, chlorine is the easiest way to sanitize and gives you the most control. If you use your spa once or twice a week, then bromine in a floater may be best.

The disadvantage to chlorine is that you must add when there is extended non use. With N2 and ozone you can probably go two or three days without chlorine. That, IMO, is where N2 helps. When there is no activity in the spa, then N2 and ozone can help keep the bacteria level down as a low level, slow acting bacteriacide.

If you use your spa a lot, then I don't feel that N2 does anything to help. The chlorine you add as you use your spa will be more than enough to keep you water very safe. I personally use bleach after use and shock weekly with MPS. I no longer use N2 or ozone. You should check and adjust your pH weekly no matter what method you use. Because bleach has a high pH, it will tend to elevate the pH in your water. Bromine has a low pH, so it will draw it down. Dichlor is the closest to neutral but will tend to drop pH. MPS has a low pH.

I have been using bleach for almost a year now and I find it the easiest chlorine to use with the least side effects. Most manufacturers frown on the use of bleach in a spa, but I believe this has more to do with the worry of spilling it than with any water issues. HotSpring, the largest spa manufacturer, does not allow the use of any pucks including bromine, so you must use granular bromine in their spas if you wish to use bromine.

You should have no problem going four months with your water through the winter. Four months is my normal water change interval, however I did skip my midsummer change because my water was in such good shape. I am at seven months now and will change at about December 1 for the winter. If you find your water goes bad mid winter in a cold area, do a partial change to get you through. Much easier.

[chem geek]

I have been using bleach for almost a year now and I find it the easiest chlorine to use with the least side effects. Most manufacturers frown on the use of bleach in a spa, but I believe this has more to do with the worry of spilling it than with any water issues. HotSpring, the largest spa manufacturer, does not allow the use of any pucks including bromine, so you must use granular bromine in their spas if you wish to use bromine.

Tony,

I think many manufacturers frown on the use of bleach because using ONLY bleach without initially using Dichlor or otherwise adding CYA to the water will result in OVER chlorinating the spa by at least a factor of 4 or more (at 104F). Without any CYA in the water, bleach alone would be too harsh on the spa, especially on the spa cover. Because the industry doesn't talk about the chlorine/CYA relationship, you get these all-or-nothing recommendations.

Richard

[Nitro]

I agree with Tony, and of course Richard.

I use my spa 2-4 times a week, and I find bleach is very easy to use. My buddy used Bromine, thinking he could go longer between his maintaince, once a week. But he soon realized, he would get into trouble if he went that long.

The way I look at it, it's easier to just get into a daily routine like brushing your teeth, instead of a 2-3 days, because you end up slacking off, forgetting etc. It takes me less then 5 min to check the water and add bleach. Frankly, if you can't find 5 min a day to take care of your tub, you shouldn't have a tub, IMO. People who travel are in a different situation, who I would recomend the Spa Pilot (salt water generator) which after tuned, will last as long, or longer than Bromine. Again IMO.

As far as PH rising using bleach, don't worry about it. If you lower your TA, and add borates you can get your PH tuned to where it won't rise at all, or very very little. I haven't added acid to my tub in three weeks. I check it everyday, because it's so easy. IMHO, Bleach is the easiest, cheapest, safest, giving you the most confidence and control out of any sanitizer.

Regarding the Spa Pilot. You still need to check the water often using the Pilot Spa, especially starting out. I was going to go with it, but I'm finding adding a little bleach every day is just too easy. I may go to the Spa Pilot someday, but I'm affraid I'll get too confident in it, get lazy about checking the water and find out the thing quit working for a few days.

Bottom line is: if your forced to check your water everyday, you will never have a proplem. Unless of course you don't know what you're doing, which wouldn't include anyone reading this forum.

[Whoneedsavacation]

IMO it comes down to : Bromine is easier to use for most people as you can leave it alone for a few days and not worry too much. We travel often, so that's a real consideration for us. However, people actually seem to report more irritation from bromine than from chlorine. I use bromine and feel no need to change, but there are lots of chlorine fans here.

[Dnepr Dave]

My wife and I soak every day and use chlorine. It's no big deal to toss a few oz. of bleach in the tub when I get out. The total chlorine and free chlorine stay about 3 to 5 ppm. I test the water every other day, shock with MPS and wash the filter weekly every couple of weeks I toss in a table spoon of spa up to adjust the ph.

Chlorine is cheap and easy!

Dave

[SouthSpa]

i was happily using Dichlor after every use until I went to buy supplies at the local spa store. The salesman said NEVER use Dichlor as it would destroy the seals on the motor and such. Now I don't know what to do.

I followed his recommendation and bought some bromine and a floater dispenser. It all looks fine on the test strips, but it's only been a few days.

[Nitro]

i was happily using Dichlor after every use until I went to buy supplies at the local spa store. The salesman said NEVER use Dichlor as it would destroy the seals on the motor and such. Now I don't know what to do.

That salesman is a moron.

The only issue with continued use of Dichlor is the rising level of CYA, which was nothing to do with the motor seals.

I followed his recommendation and bought some bromine and a floater dispenser. It all looks fine on the test strips, but it's only been a few days.

If you check you might find that bromine that you put in that dispenser has chlorine in it. Then tell that to the salesman.

[Nitro]

IMO it comes down to : Bromine is easier to use for most people as you can leave it alone for a few days and not worry too much. We travel often, so that's a real consideration for us. However, people actually seem to report more irritation from bromine than from chlorine. I use bromine and feel no need to change, but there are lots of chlorine fans here.

Like I said, if I traveled alot I'd just get the Spa Pilot. But each to his own.

[Nitro]

My wife and I soak every day and use chlorine. It's no big deal to toss a few oz. of bleach in the tub when I get out. The total chlorine and free chlorine stay about 3 to 5 ppm. I test the water every other day, shock with MPS and wash the filter weekly every couple of weeks I toss in a table spoon of spa up to adjust the ph.

I could get away with testing water every other day, but what fun would that be? I like testing everyday.

[newspaguy]

So when you all refer to using "bleach" we are talking straight off the shelf regular old unscented chlorox?????? Ive been using Dichlor every other day now for about a week and a half. Can I go ahead and start using bleach now as long as I watch the ph levels? This won't be any harsher on the tub components or cover than the dichlor will it?

Nitro, you mentioned adding borates to your tub......what type of product name would I look for, what does it do, and how do I use it along with the bleach.

Perhaps Chem Geek can help me on the final question......is there any real difference between the chlorine in bleach vs. the chlorine in dichlor (other than its stabilized)? Is chlorine is chlorine is choline when it all comes down to it

[Nitro]

So when you all refer to using "bleach" we are talking straight off the shelf regular old unscented chlorox?????? Ive been using Dichlor every other day now for about a week and a half. Can I go ahead and start using bleach now as long as I watch the ph levels? This won't be any harsher on the tub components or cover than the dichlor will it?

Yes, "regular old unscented Clorox" bleach.

Nitro, you mentioned adding borates to your tub......what type of product name would I look for, what does it do, and how do I use it along with the bleach.

You can use Borox "Mule Team", but you have to counter it with acid because it will raise your PH.

The easy way is to use Gentle Spa, which is PH netural. Better yet get the pool version, which is cheaper.

Perhaps Chem Geek can help me on the final question......is there any real difference between the chlorine in bleach vs. the chlorine in dichlor (other than its stabilized)?

No, they are the same except the CYA in Dichlor, and bleach does add more salt to the water, which is not a problem. Chem Geek can explain that to you.

Is chlorine is chlorine is choline when it all comes down to it

Yes, and I know Chem Geek will tell you the same, because he's where I learned it from.

[chem geek]

Perhaps Chem Geek can help me on the final question......is there any real difference between the chlorine in bleach vs. the chlorine in dichlor (other than its stabilized)?

No, they are the same except the CYA in Dichlor, and bleach does add more salt to the water, which is not a problem. Chem Geek can explain that to you.

Is chlorine is chlorine is choline when it all comes down to it

Yes, and I know Chem Geek will tell you the same, because he's where I learned it from.

I think you pretty much summed it up well. To convince yourself that the chlorine is the same, take a look at Dichlor here, Trichlor here and Cyanuric Acid (CYA) here and note that they are all very similar except that Dichlor has two of the hydrogen in CYA replaced with chlorine atoms while Trichlor has three of them replaced.

When dissolved in water, Dichlor and Trichlor partially hydrolyze which means they combine with water to release hypochlorous acid which is the active form of chlorine. Chemically, it's the following:

NaC₃Cl₂N₃O₃•2H₂O + H₂O <---> C₃H₃N₃O₃ + 2HOCl + NaOH

Dichlor + Water <---> CYA + Hypochlorous Acid (chlorine) + Sodium Hydroxide (lye)

Bleach is sodium hypochlorite, NaOCl, so in water forms hypochlorite ion, OCl^-, as well as hypochlorous acid, HOCl. All of these chemical species are in chemical equilibrium with each other with the net result that the chlorine in water is IDENTICAL regardless of source. The only difference is that for every 10 ppm Free Chlorine (FC) added by Dichlor, it also increases CYA by 9 ppm (and for every 10 ppm FC added by Trichlor, it also increases CYA by 6 ppm). As was mentioned by Nitro, bleach adds salt to the water so for every 10 ppm FC added by bleach you are also adding 6 ppm "extra" salt. I say "extra" salt because all the chlorine you add will also get converted to salt when it gets used up. That is, all sources of chlorine convert 10 ppm FC into 6 ppm salt. So using bleach increases the amount of salt in the water twice as fast as Dichlor (for equivalent chlorine amounts) since 10 ppm FC of bleach ends up adding and converting to 12 ppm salt.

The above simply means that it does not matter whether you add Dichlor to the water or whether you add a combination of Cyanuric Acid (CYA) and bleach. You end up with IDENTICAL chemicals in the water except for the "extra" salt from bleach. There is a difference in pH as well, but that can be easily adjusted.

With any chemical addition to a spa or a pool, one should do so slowly over a return flow with the pump running to ensure thorough mixing. Once diluted in the water, there is no way to tell the difference between the chlorine added by Dichlor vs. the chlorine added by bleach.

You might ask why use bleach over Dichlor and the simplest answer is that continued use of Dichlor will likely increase the CYA level and higher CYA levels make chlorine less effective both for sanitation and for oxidation (keeping the water clear). On the other hand, using only bleach without first using some Dichlor or adding some pure CYA would be TOO strong so the normal prescription is to use Dichlor for about a week and then switch to bleach until the next drain/refill.

Richard

[Nitro]

Richard,

I might be turning into a geek too, because I actually understood everything in your post.

I do have a question though. We add CYA before using bleach, because bleach by itself would be too strong. However, could we not just use less bleach? For instance, on a fresh add 1 TBS to shock and 1 tsp to maintain. OR is there something else going on, other then UV protection?

[SouthSpa]

"so the normal prescription is to use Dichlor for about a week and then switch to bleach until the next drain/refill."

So in keeping with the original thread of "Plain and Simple", one could use a teaspoon of Dichlor every day for one week and then switch to the same amount of plain 'ole Clorox each day until the next drain/refill? And the only other routine is shocking once per week? Do I have that right?

[Nitro]

"so the normal prescription is to use Dichlor for about a week and then switch to bleach until the next drain/refill."

So in keeping with the original thread of "Plain and Simple", one could use a teaspoon of Dichlor every day for one week and then switch to the same amount of plain 'ole Clorox each day until the next drain/refill? And the only other routine is shocking once per week? Do I have that right?

I've been doing it for a month in a half, and I'm very happy with this method. Maintaining the water is almost as much fun as soaking in it.

The amount of bleach you use will vary depending on bather loads etc. You will want to test the water a lot, especially in the begginning. But after a while you'll get a good feel for how much you need, and it becomes real easy.

Another thing you might consider is using MPS once a week to help break down wastes and reduce Combined Chlorine which can build up if you have high bather loads.

[chem geek]

Richard,

I might be turning into a geek too, because I actually understood everything in your post.

I do have a question though. We add CYA before using bleach, because bleach by itself would be too strong. However, could we not just use less bleach? For instance, on a fresh add 1 TBS to shock and 1 tsp to maintain. OR is there something else going on, other then UV protection?

There are three problems with using bleach only even at lower amounts. First, is that it has to be a LOT lower amount to be similar to the Dichlor then bleach concentration -- at least a factor of 4 or more. Depending on spa temperature, it may need to be 1/10th as much (lower temps have the spread between pure bleach and bleach with CYA be larger; at 98F it's about a factor of 6). Second, is that you need a certain quantity of bleach (or other oxidizer) to oxidize the ammonia and urea in your sweat and urine (among other things). Third, to be safely sanitary against the bacteria that causes hot tub itch, you want a fairly high active chlorine concentration. My 4 ppm FC with 20 ppm CYA guideline is conservative, but I don't think one should go much lower than 4 ppm FC with 50 ppm CYA (or 1.6 ppm FC with 20 ppm CYA) given what I saw in the chart of hot tub itch/rash/lung incidents (it's not definitive, but "seems" that problems occur in Dichlor-only approaches after 1-2 months of use).

Basically, the CYA is a chlorine buffer so it's a nice thing to have to moderate chlorine's strength while providing a reserve for more chlorine. This is especially helpful in smaller tubs where the swing in FC is larger (since a fixed amount of chlorine is needed to oxidize the bather contaminants, but there is a smaller volume of water so the chlorine concentration is higher). In smaller tubs, one could have a higher CYA level such that the higher initial FC after a soak isn't so strong -- then one would target a higher low FC at the start of a soak to have comparable disinfection capability.

Richard

[cashews]

My wife and I soak every day and use chlorine. It's no big deal to toss a few oz. of bleach in the tub when I get out. The total chlorine and free chlorine stay about 3 to 5 ppm. I test the water every other day, shock with MPS and wash the filter weekly every couple of weeks I toss in a table spoon of spa up to adjust the ph.

I could get away with testing water every other day, but what fun would that be? I like testing everyday.

Just want to chime in and say, I appreciate hearing others test their spas daily. Once I get my biohazard (ha ha ha....pseudomonas) cleaned up and the tub refilled, I will test daily.

FYI, my chlorine level must have gotten low, or the ozonator broke down my chlorine too quickly, and let a nasty bacteria take hold. Please watch your chlorine levels if you have an ozonator!!!

I am determined to turn off my ozonator and keep my chlorine level stable.

Nitro...can I ask, do you just use Chlorox 6%? Do you measure specifically for the ounces, or eyeball it.

THanks...

[Dnepr Dave]

I used to test daily, but found that nothing changed in two days, so I went to every other day testing.

With our 200 gallon Caldera, I add 2 oz of plain old Chlorox after we soak.

Dave

[Nitro]

Richard,

I might be turning into a geek too, because I actually understood everything in your post.

I do have a question though. We add CYA before using bleach, because bleach by itself would be too strong. However, could we not just use less bleach? For instance, on a fresh add 1 TBS to shock and 1 tsp to maintain. OR is there something else going on, other then UV protection?

There are three problems with using bleach only even at lower amounts. First, is that it has to be a LOT lower amount to be similar to the Dichlor then bleach concentration -- at least a factor of 4 or more. Depending on spa temperature, it may need to be 1/10th as much (lower temps have the spread between pure bleach and bleach with CYA be larger; at 98F it's about a factor of 6). Second, is that you need a certain quantity of bleach (or other oxidizer) to oxidize the ammonia and urea in your sweat and urine (among other things). Third, to be safely sanitary against the bacteria that causes hot tub itch, you want a fairly high active chlorine concentration. My 4 ppm FC with 20 ppm CYA guideline is conservative, but I don't think one should go much lower than 4 ppm FC with 50 ppm CYA (or 1.6 ppm FC with 20 ppm CYA) given what I saw in the chart of hot tub itch/rash/lung incidents (it's not definitive, but "seems" that problems occur in Dichlor-only approaches after 1-2 months of use).

Basically, the CYA is a chlorine buffer so it's a nice thing to have to moderate chlorine's strength while providing a reserve for more chlorine. This is especially helpful in smaller tubs where the swing in FC is larger (since a fixed amount of chlorine is needed to oxidize the bather contaminants, but there is a smaller volume of water so the chlorine concentration is higher). In smaller tubs, one could have a higher CYA level such that the higher initial FC after a soak isn't so strong -- then one would target a higher low FC at the start of a soak to have comparable disinfection capability.

Richard

That makes sense. I think dealing with tsp's of bleach would be a hassle anyway. It's easier/safer for me to pour it into a tall measuring cup. No splash.

Now to go on the other end. Why not have CYA higher (say 50 or 100), then just use more bleach? Would that do a better job of oxidizing waste (sweat etc)?

Maybe I guess I should be asking, how did you come up with CYA of 20?

[Nitro]

Nitro...can I ask, do you just use Chlorox 6%? Do you measure specifically for the ounces, or eyeball it.

Yes, I use regular Clorox 6% bleach, I get it by the 1.4 gal at Walmart. I started using this bottle about a month ago and used about 1 gal so far. So 1 gal/mo is about what I've used. However, I did a lot of unnessassry shocking in the beginning.

I have a tall (6" tall by 3" wide) measuring cup that measures by the oz. I just pour the bleach in it over the sink. Then pour it directly in the center of the tub, with the jets on. This measuring cup works perfect, because there's no splash. I could probably eyeball it, but I like to know how much I'm using and how much I need to use.

[Nitro]

I used to test daily, but found that nothing changed in two days, so I went to every other day testing.

With our 200 gallon Caldera, I add 2 oz of plain old Chlorox after we soak.

Dave

I just can't bring myself to leave my tub alone for two days. It just wouldn't be right.

But not much changes in my tub in two days either, if I don't use it. I could probably leave my tub 3-4 days after shocking it and still have a good residual.

[chem geek]

Now to go on the other end. Why not have CYA higher (say 50 or 100), then just use more bleach? Would that do a better job of oxidizing waste (sweat etc)?

Maybe I guess I should be asking, how did you come up with CYA of 20?

Going the other way, with higher CYA and FC but keeping their ratio roughly constant, would result in the same disinfection and oxidation rates but would give one more capacity of chlorine. It won't oxidize bather waste any faster -- only a higher "active" chlorine concentration would do that with the downside of oxidizing hot tub covers, swimsuits, etc. faster as well. It will, however, guarantee that you won't run out of chlorine since you have so much more in reserve and it will last longer, but as the FC level drops the disinfection/oxidation rate will drop as well.

You bring up an interesting point. If one were most concerned with having a fairly constant disinfection/oxidation level even when there is a fairly large swing in FC daily due to bather load, then having a high FC and CYA level so that the ratio doesn't change much when the FC drops would be a way of maintaining that constant disinfection/oxidation rate. In fact, I'm thinking of increasing the CYA level in my pool for that very reason since I'm currently at 30 ppm CYA but vary in FC from around 2-3 to 5-6 ppm since I only add chlorine twice a week (I have an opaque electric safety cover so have relatively low 1 ppm FC per day chlorine demand with the pool used/open every day for 1-2 hours).

By the way, you should understand that though the chemistry of chlorine/CYA is very clear and not disputed and that in labs the kill rates against bacteria, viruses, protozoan oocysts and oxidation of organics all show rough proportionality to the "active" chlorine level (i.e. hypochlorous acid and affected by CYA level), the industry (that is, the chlorinated isocyanurate manufacturers/distributors) believes that this chemistry doesn't apply to "real pools" and use a benchmark of not seeing any outbreaks correlated with CYA level as proof (ignoring protozoan oocysts which are resistant to chlorine) -- this is what will likely be said in the APSP-11 standard that is being developed. This is in spite of the fact that in real pools the CYA effect on ORP is also seen. Basically, as I told some of the APSP-11 committee members at the NEHA conference, most bacteria and viruses are relatively easy to kill so you won't see an obvious outbreak correlation with CYA and that smaller disease transmission between a few people isn't likely to get reported. Also, algae is much harder to kill so is where you see the CYA effect most dramatically (I didn't even bring up what we've seen here regarding hot tub and hot tub itch since it's not nearly as clear cut).

You should also be aware that the EPA has a limit on FC in pools of 4 ppm and in spas of 5 ppm and that this is based on drinking water standards (i.e. ingestion of quarts of water every day). From an ingestion point of view, it is the FC that matters, independent of CYA, because the chlorine that is bound to CYA will get released so it is the capacity that matters, not the "active" chlorine concentration. Since no one spent the money to prove to the EPA that soaking in chlorinated water, especially with CYA, does not result in the equivalent to ingesting quarts of water, the standard is as I described. Realistically, a hot tub does open one's pores so there is more likelihood for chemicals to enter in through the skin, but it's not clear whether that applies (in practice in terms of full absorption into the body) to the chlorinated isocyanurates or only to hypochlorous acid. The primary chlorinated chemical species at normal spa and pool pH are negatively charged and larger (i.e. have a CYA triazine ring) as opposed to hypochlorous acid that "looks like" water with a hydrogen atom replaced with a chlorine atom (that's what makes it so effective against pathogens as it readily enters those cells). Many cell surfaces are negatively charged so tend to repel negatively charged chemical species. This is the main reason why hypochorite ion isn't as effective as hypochlorous acid.

Richard

[B0Darc]

I have been using bleach for almost a year now and I find it the easiest chlorine to use with the least side effects. Most manufacturers frown on the use of bleach in a spa, but I believe this has more to do with the worry of spilling it than with any water issues. HotSpring, the largest spa manufacturer, does not allow the use of any pucks including bromine, so you must use granular bromine in their spas if you wish to use bromine.

Tony,

I think many manufacturers frown on the use of bleach because using ONLY bleach without initially using Dichlor or otherwise adding CYA to the water will result in OVER chlorinating the spa by at least a factor of 4 or more (at 104F). Without any CYA in the water, bleach alone would be too harsh on the spa, especially on the spa cover. Because the industry doesn't talk about the chlorine/CYA relationship, you get these all-or-nothing recommendations.

Richard

It's good to make note that the manufacturer is looking for the safest and simplest recommendation to not make it all sound so overly complicated. Never discourage the prospective customer or give them options they can screw up... because they will (!) or worse decide a spa is too much like work and not buy today.

There's more than one way to sanitize your spa water and it can be very simple, but deciding on a "best" option is missing the point. Different folks soak differently ..like daily or twice weekly? These are critical factors in your choice for sanitizing strategy. I'm from the chem geek school of Clorox, but I'm a daily bather and I like the chlorine level low when I get in. When it's time to change the water I dump in an enzyme treatment *before* draining to dissolve the bio-layer build up and pick up a canister of Dichlor and pH Down... then I just buy a gallon of Clorox at the grocery store as needed. I don't even use MPS, I just double up on the Clorox once a week before maintenance day (filters)

This has worked for me because it's just me and she and 15-30 minutes 6 days a week ...and I am doing the water chemistry. If she was doing it we may be using bromine frog or baqua because it's just easier. As long as the germs are dead, your skin is happy, and the water is clear, it's "mission accomplished", but the real question is what level routine fits how you soak and who is performing the maintenance. I can say one thing ...Clorox is CHEAP, and for me the routine is easy, once I came to the understanding of what is really going on over the 120 days from new water to lawn food. Oh and I'm of Scottish descent ;-) ...did I mention Clorox is CHEAP?