Sodium Bromide Bank & Sunlight

[h20gal]

I have a 3,300 gallon, 8Wx13Lx6' deep fiberglas exercise pool. It is covered except the first 4-5 days of the season when I solar heat it & when we are in it which is about an hour a day, 3-4 days/week in the summer. I understand the chemical balance & use the 3-step bromine procedure. Upon opening the pool a week ago, I drained off about 16" of water, added new (from well), added Metal Gone, added 16 oz Sodium Bromide, balanced the water over several days, & circulated three days running to clear up a bit of cloudiness, cleaning the cartridge filter a couple times in the process. I had the pool covers off all day for 4 days to solar heat the water. Right now, Bromine 0, pH 7.6, TA 75-100, CH 175.

My question is this: Does sunlight render the Sodium Bromide Bank ineffective or less effective? The reason I'm asking is Day 2 of solar heating (covers off), I tried to get a BR reading of 10 from the first shock treatment (used 3 times MPS, or about 16 oz, & only got a reading of 5). Within an hour the BR went down to 0. A couple days later (Day 4 of solar heating, covers off), I tried to get a BR reading of 10 from the second shock treatment using 240 oz of liquid bleach (way over what is recommended). Again, I only was able to get a BR reading of 5 & within an hour the BR went down to 0. I've had a floater in the pool the whole time with BR/CL tablets & still the BR is 0. The pool has been totally covered for about 3 days now because of cooler weather & still the BR is 0.

What do you experts think? Does sunlight render the Sodium Bromide Bank ineffective or less effective?

Many thx.

[chem geek]

Sunlight doesn't do anything to the bromide bank, but it does break down bromine and since bromine isn't as protected by Cyanuric Acid (CYA) (unless the CYA level is high enough to shield lower depths in the water directly), it is the bromine itself that is dropping in sunlight. However, it usually doesn't drop as fast as you are describing so there may be something else going on.

[h20gal]

Both times that I shocked were in the early evening when the sunlight was not on the water at all, however, the water had been in sunlight all day (with bubble cover). Would that be the reason for the BR reading of 5 max & the drop to 0 fairly quickly? Does the sunlight's affect on the water carry over for additional hours/days or is it an issue on the bromine level only when the sun is directly on the water?

Do you think I should wait to shock again until AFTER the solar heating process is completed (a couple more days)? Then the pool will be covered most of the time again & the heat will be kept stable with a propane heater?

Thx.

[waterbear]

2 things to consider:

How are you testing btw. IF you are testing with DPD it is possible that the bromine has gone so high after shocking that has bleached out the test (this will not happen with FAS-DPD or OTO testing) and reads 0 ppm when it is actually over 10 ppm!

If the santizer level is dropping quickly it indicates a sanitizer demand...perhaps a nascent algae bloom. If your bubble cover is clear then some UV would get through and destroy much of your sanitizer residual during the day and allow an algae bloom to start. This nascent bloom might not be enough to even make the water cloudy but could be enough to consume any sanitizer very quickly.

[h20gal]

Waterbear - Re your 1st point above, I'm using the Taylor K-2005 DPD test kit (I know not your first choice), which is what I've used for years without this current problem. Is there a separate FAS-DPD or OTO kit available just for testing BR? If the BR was over 10 ppm, how many days would it take to come down to a readable DPD level? The last super shock was done on 6/3/12. The water looks crystal clear now (was a bit cloudy at first) & the BR reading is still 0 today, 6/7, as it has been since 6/4. Note, the pool has been totally covered the last 3 of 4 days.

Re your 2nd point above, yes, the bubble cover is clear. If this scenario is happening, which is the opposite of your 1st point, do you think I should wait to shock again until AFTER the solar heating process is completed (a couple more days)? Then the pool will be covered most of the time again, the heat will be kept stable with a propane heater & the bromine level won't be affected so much by the sunlight?

Also, when exactly should I do the BR test after shocking? In 5 minutes, 15 minutes, 1/2 hour? Note, I can mix the shock in the water manually with the pole broom + use the circulating pump.

Thx.

[waterbear]

Waterbear - Re your 1st point above, I'm using the Taylor K-2005 DPD test kit (I know not your first choice), which is what I've used for years without this current problem. Is there a separate FAS-DPD or OTO kit available just for testing BR? If the BR was over 10 ppm, how many days would it take to come down to a readable DPD level? The last super shock was done on 6/3/12. The water looks crystal clear now (was a bit cloudy at first) & the BR reading is still 0 today, 6/7, as it has been since 6/4. Note, the pool has been totally covered the last 3 of 4 days.

IF you look in the lid of your test kit and read the small print at the bottom of the chlorine test section it will tell you how to use the molded lines on the small comparator to do a 1:1 dilution and a 4:1 dilution of your sample to test higher chlorine or bromine levels.

You can also get an inexpensive 2 way tester (even walmart has them) that tests chlorine/bromine and pH. The chlorine/bromine side has yellow color blocks. This is an OTO test and it will not bleach out (but it is not very precise either) If you do this test and the color is deep yelloow, orange, or brown then you have probably bleached out the DPD test in your K-2005

Re your 2nd point above, yes, the bubble cover is clear. If this scenario is happening, which is the opposite of your 1st point, do you think I should wait to shock again until AFTER the solar heating process is completed (a couple more days)? Then the pool will be covered most of the time again, the heat will be kept stable with a propane heater & the bromine level won't be affected so much by the sunlight?

Also, when exactly should I do the BR test after shocking? In 5 minutes, 15 minutes, 1/2 hour? Note, I can mix the shock in the water manually with the pole broom + use the circulating pump.

Thx.

Are you only using sodium bromide and MPS right now or do you also have bromine tabs in a floater or feeder? Also, have you tried shocking with sodium hypochlorite? (bleach or liquid chlorine).

[h20gal]

Waterbear - Thx for the dilution tip. I did both the 1:1 & 4:1 dilution tests for BR. Both came up 0 tonight. So, over-sanitization isn't the problem.

Re your questions: Are you only using sodium bromide and MPS right now or do you also have bromine tabs in a floater or feeder? Also, have you tried shocking with sodium hypochlorite? (bleach or liquid chlorine). As I stated in my first post above, I established the sodium bromide bank, super shocked with MPS the first time, super shocked with liquid bleach the second time & yes, there is also a floater with BR/Cl tabs. Still have BR at 0 after the initial reading of 5 ppm max from both super shock treatments.

So, with the dilution tests showing BR at 0, do you think I should wait to shock again until AFTER the solar heating process is completed (a couple more days)? Then the pool will be covered most of the time again, the heat will be kept stable with a propane heater & the bromine level won't be affected so much by the sunlight?

Also, when exactly should I do the BR test after shocking? In 5 minutes, 15 minutes, 1/2 hour? Note, I can mix the shock in the water manually with the pole broom + use the circulating pump.

Thx much.

[waterbear]

Ok, We have established that you have a high santizer demand in your pool. You need to keep shocking until the santizer level is more stable. I would use bleach or liquid chlorine for shocking Part of the problem might be the sun destroying the bromine and that could lead to a nascent aglae bloom (as I said before) that would consume the sanitizer even faster. It is important to keep up the santizer level so you don't get a full blown algae bloom. You might want to consider getting some Poyquat 60 algaecide (make sure the active ingredient is:

Poly{oxyethylene(dimethyliminio)Ethylene (dimethyliminio)ethylene dichloride} 60%

since there are "60% algaecides" on the market that are NOT polyquat and do not work as well!)

and add 1 oz per 1000 gallons (use about 3 to 3.5 oz for your swim spa initially) and then weekly add an additioal .24 to .4 ounce. In your case adding an additional ounce weekly should suffice.

Bottom line, you need to do whatever it takes to keep sanitizer in the water as much as possible until the problem is resolved. Otherwise you can get a full blown algae outbreak that will be even more headaches.

Bromine would not be my first choice in a swim spa that is exposed to the sun and also depends on direct heating (or with a clear solar cover) for precisely the reasons you are seeing now. I would treat it like a swimming pool exposed to the sun and use chlorine and maintain a CYA level of 40 or 50 ppm or possibly higher. However, that would requires you draining it and flushing it since that is the only way to convert from organic bromine (the tabs) to chlorine.

[h20gal]

Thank you, Waterbear, for your prompt feedback. I've decided to stop the solar heating process with bubble cover today & to start heating with propane. This will enable me to keep the two thick spa covers on the pool all the time except when the pool is actually being used (every other day for about an hour only). I will super shock with bleach until I get a 10 ppm BR reading. With the pool solidly covered, I should be able to maintain BR 4-6 going forward (which I've been able to do in the past). I will pick up some Polyquat as well.

I don't want to switch to chlorine. I really can't. The little pool is part in ground & part above ground (on a hill). I can't drain it all the way as it could completely pop out of the ground when no water is in it (per Viking Pools, the manufacturer).

I'll give you an update in about a week. Thx so much.

[waterbear]

Actually any pool can be completely drained but there are special precautions that need to be taken. Fiberglass pools often need to be braced to they do not buckle, which is more of a problem than popping out of the ground. ANY pool can pop out of the ground when empty and the water table is high but there are ways around that also. It just means it is not a job for a homeowner but for a pro. Even ingound vinyl pools cannot be completely drained because the liner can wrinkle or shift without special precautions such as a vacuum pump behind the liner to keep it in place while it is empty.

However, if you normally keep the pool covered then bromne is workable.

As far as heating. solar covers, even clear ones, do not heat the water, they prevent heat loss from evaporation overnight, which can be significant. If you want to heat the water using the sun it is best to keep the pool uncovered since this is more effective or better yet, install solar heating. Otherwise I would use the propane to get the pool up to temperature and use the cover to prevent overnight heat loss from evaporation.