New BBB User

[knightoj]

I posted this last night but then it must have got lost in the move to the new server. I initially had a response from Watermom that was helpful. I"m using the Taylor K 2006 testkit and have a 18,000 gallon fiberglass pool. Water temp was about 71 degrees.

My readings are:
TA 120
CYA 60
PH 7.4
FC 4.0
CC 3.5
CH 160

I raised the FC level to 10 times the CC level as recommended in the Taylor test guide to get rid of the CC. Next day the CC was still 3.5. I was using 3" Chrloine Tablets from In the Swim until about a week ago but now use clorox. I followed the instructions on how to test the FC and CC using the Taylor guide. Watermom thought my CC reading might be wrong because it's so high. And she may be right since the water does not smell like chlorine. Any suggestions on dealing with the CC? Thanks for your help.

[PoolDoc]

Yes, there were some bumps moving from there to here -- most of the attachments got disconnected :(

Anyhow, there are two likely possibilities with your CC.

=> First, you could be making a testing error. But if you are using the K2006 and ONLY the DPD drops + the DPD-FAS drops, and have pre-rinsed your tube, it's hard to make that sort of error.

=> The CC could be real. If so, get some borax, and raise your pH! If it IS real, and isn't stinky yet. Also, do NOT cover the pool -- the chloramines leave as chlorinated gases, and can damage a cover. If they are real, it will take time, sun, and quite a bit of chlorine to get rid of them. Don't work about the break-point calculations -- there are only few situations where those calculations actually apply, and most of them are NOT in pools!

More info here:

http://www.poolsolutions.com/gd/spring-swimming-pool-startup-problems.html

Ben / PoolDoc

[knightoj]

To make sure I get this right. I should raise the PH level and then raise the Chrlorine levels each night, check it in the morning, raise the chlorine level if needed until the CC goes away. Should I raise it to the shock levels from the Best Guess Chart? Thanks for your help.

[PoolDoc]

That's it, exactly.

But let us know if you do NOT see chlorine levels dropping overnight.

Ben

[knightoj]

I've go it to the point where the Chlorine levels are consistent from the evening to the morning. Last night, I upped the FC level to 17 and this morning it was still holding at 17. CC is still at 3.5. Do I continue with the process and then the CC will eventually go away?

[PoolDoc]

Ok, you've made progress. But it's still not clear to me what the source of the problem was. Please read through this PoolSolutions page, and see if anything jogs your memory:
http://www.poolsolutions.com/tips/why-has-my-pool-chlorine-disappeared.html

Ben / PoolDoc

[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:

Add nitrogen into the pool in a form that can react with chlorine, OR
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