New BBB User

[knightoj]

None of the things mentioned in the link apply to my situation. It is very windy right now with a lot of dust blowing around right now. Could that be a cause? I also just switched to the BBB method after using Tri Chlor tablets until about three weeks ago. Thanks for you help.

[PoolDoc]

There are two ways to end up with high persistent combined chlorine (CC) in your pool:

1. Add nitrogen into the pool in a form that can react with chlorine, OR
2. Put something in the pool that screws with the test.

In the first category are things like:

• foamy algicides
• granular algaecides based on ammonia
• degraded stabilizer (ammonia, again)
• urine or lots of sweat
• some fertilizers
• other stuff I haven't though about, or heard of

In the second category, there are several possibilities but "oxy-shocks" or "non-chlorine shocks" based on potassium monopersulfate stands out. MPS will test as CC, even though there's no chlorine in it, and it's completely ineffective as a sanitizer ( unlike combined chlorine).

Of course, I'm sure there are possibilities I don't know about.

But, if you can't think of any one of those that might be the explanation, it's probably best to simply hang on, and see if the problem resolves itself.

Oh, just to rule out one more possibility: exactly what test kit, and what test method are you using to test for chlorine?

Ben / PoolDoc

[knightoj]

Thanks for your quick reply. Last year before I found this forum I had an algae problem and was using foamy algecides at least once a week. Could this be a carryover from last year?

I'm using the Taylor test kit - K2006 with the DPD-FAS drops.

[chem geek]

So just to be sure, you add DPD powder to a 10 ml sample and it turns pink/red. You then add R-0871 until it turns clear which in your case takes 8 drops so 4 ppm FC. Then to that same sample you add 5 drops of R-0003 and the sample turns pink/red again. Then you add R-0871 until it turns clear which in your case takes 7 drops so 3.5 ppm CC. Do I have that right? I'm just trying to make sure that you didn't start with a new sample when you measured the CC and that you measured it using the same sample you used to measure FC (i.e. that you did the CC test following the FC test using the same sample water).

[knightoj]

Yes, that's the method I used with the same water. I think I'm making progress though. I raised the FC to 18ppm last night and it held steady. This evening FC was 17ppm and CC was down to 1.5. So maybe I need to give it more time.

[aylad]

The foamy algaecides were probably your culprit....I can't explain the chemistry, but I do know that they break down into chemicals that can create quite a chlorine demand. Keep it at shock level and stay the course--once you break the stuff all the way down it will be much easier to maintain.

Janet