Defective K-2006 Kit?

[droweye]

Thank you for all the feedback! I guess for the time being, I'll run the pool as it is and maintain the best guess FC level. I'll let the CYA decrease on its own or drain a small portion for the summer to lower CH.

[PoolDoc]

That'll work.

Two cautions:

1. If you take your water to be tested by a pool store that can accurately measure either your FC or CYA levels, they will freak out, and give you dire warnings that you'll soon get hairy palms, that your great-grandmother and great-niece will surely die of instant cancer of the toenail and nasal hair, and that your garden plants will mutate and eat you. Ignore them.

2. If you get algae, you will either have raise your chlorine VERY high . . . and it will stay there for weeks OR you'll have to use a lot of polyquat ($$$) or you'll need to add a small amount of sodium bromide. Your best option: maintain circulation and chlorine and don't get algae. Second best: sodium bromide in as small amounts as possible. I'll cover this option before summer.

[droweye]

Will adding some Borates be a better alternative over sodium bromide and polyquat? I've been reading through the guides which suggests that bromine interferes with chlorine chemistry lowering its effectiveness and that "once a bromine pool always a bromine pool" until you drain and refill.

[waterbear]

2. If you get algae, you will either have raise your chlorine VERY high . . . and it will stay there for weeks OR you'll have to use a lot of polyquat ($$$) or you'll need to add a small amount of sodium bromide. Your best option: maintain circulation and chlorine and don't get algae. Second best: sodium bromide in as small amounts as possible. I'll cover this option before summer.

I would not recommend the sodium bromide. Some SWCG cells don't like it! Another option si 50 ppm borate.

[PoolDoc]

Thanks, Waterbear . . . but I haven't seen that data. Could you email me (or post in the China Shop) the details on negative bromide / SWCG interaction?

Will adding some Borates be a better alternative over sodium bromide and polyquat?

Hi Droweye; I'm checking on the bromine / SWCG interaction, and will let you know, as soon as I have definitive info, one way or the other.

The "Once a Bromine . . ." pool page is is something I wrote 15 years ago, and is really only accurate with respect to pools on which BCDMH tabs (or other dimethyl hydantoin based forms of bromine) have been used. I revised that page somewhat to reflect those facts, but need to take it a step further. Where sodium bromide is used, on each conversion cycle (by chlorine) from bromide to bromine, a small portion of the bromide is permanently change to bromate. So over a period -- possibly a couple of weeks -- most of the bromide is rendered inactive.

BUT, there's no downside to using borates . . . unless your have a dog you want to breed who drinks daily from your pool or spa. (In that case, there's a small chance the dog might get enough borates to affect his fertility.) So, unless dogs are an issue, going with the borates is all good.

[waterbear]

Thanks, Waterbear . . . but I haven't seen that data. Could you email me (or post in the China Shop) the details on negative bromide / SWCG interaction?

Don't have the data on hand. It was just some manufacturer's warnings that had crossed my path that their units were not compatible with sodium bromide (and off the top of my head I do not remember which). It does not apply to all SWCGs (and I suspect it has to do with the cell electrode material since the some of the units made specifically for spas to generate bromine used carbon electrodes or possibly the fact that bromine cannot be stabilized by CYA and the cell cannot product enough to maintain a desired level) since I do know that the PoolPilot units are compatible with bromine and even give directions on the amount of sodium bromide to add to generate bromine instead of chlorine in their PoolPilot SoftTouch manual. However, they do caution against the use of hydrogen peroxide as a chlorine neutralizer and indicate it can damage their cell in their pool pilot digital manual.

I do remember a post on a different forum by PoolSean where he said to turn of the SWCG for a few weeks if adding sodium bromide as an algae treatment since the cell could not produce enough bromine to maintain a residual without turning up the output ant that would shorten cell life,which makes perfect sense.

[PoolDoc]

I talked to Sean and Richard about this, and have thought about this a bit. The consensus seems to be that it is fine to use bromide with an SWCG, but that you need to pay attention to what you are doing (like so many other things!).

1. Bromide / bromine does not damage SWCG plates.
2. Bromide DOES tend to increase LOAD on an SWCG because it de-stabilizes the halogen residual (which is, after all, the point of using it!)
3. Increased 'on-time', from whatever cause decreases SWCG life.
4. When using bromide, care must be taken to not overload the SWCG. This is more likely where the SWCG is switched by an ORP controller.
5. Bromide is primarily of benefit when CYA is very high (>100 ppm). If CYA is lower, simply adding bleach to raise the FC to an appropriate level would probably be a better choice.
6. When CYA is very high, adding bromide to achieve an free halogen residual may well be appropriate.
7. Uncertainties include the time it will take to convert bromide to bromate, and the appropriate bromide dose.

[droweye]

One last question about my current pool condition. Is it advisable to drain half of my pool and refill before summer starts due to high CH and CYA? My CSI is currently 0.08, suggesting that it's safe @ T= 60 F. The CSI @ T = 80 F is 0.26 which is still safe.

My only problem right now is that since installing the SWCG has a rising pH, which I'm lowering with muriatic acid every week. I've dug through the pool forum and one suggestion is lowering TA to 80, but I don't have a aerator. According to the poolcalculator my pH should lower by ~0.8 from half gallon of addition of 31% muriatic acid, but even doing that my pH only went down to 7.6 from 7.8.

I forgot to mention that in my region it has been recently windy, and this Monday we had a brief thunderstorm. This may have possibly have aerated my pool and raised the pH.