HELP...need to lower CC and raise FC

[Westy]

I've just finished a partial drain/refill cycle on a "new" (for us) pool at house we bought a few months ago. Due to the use of pucks, I found the pool severely overloaded with CYA. I've got CYA levels to about 40. The pool has had very low to nonexistant FC levels for about 3 months while we moved and I got the CYA under control. TC and FC levels were testing at basically zero. A couple of days ago, I added chlorine to about 15 ppm. Today, FC reads zero, TC reads 4-5 ppm. I suspect I've formed chloramines and combined the chlorine that I added. Do I need to superchlorinate to break up the CC and form some FC? This has been a real chore and I want to get it right without wasting money on the fix, but I've got to get the CC down and the FC up! Any help would be appreciated.

[dynamictiger]

To reduce your level of 4-5 combined you need to shock again to about 20 mg/l or ppm. This should deal with this and help clean the water up.

HTH

[Westy]

I shocked today (with liquid chlorine) to 25 ppm. One hour later free chlorine reads zero. Pool looks great....but all chlorine is combined. Do I keep this up? Actually, I guess I have no choice?

[dynamictiger]

You are correct, although having said that why are all your chlorines instantly combining? This usually indicates a large dirt load somewhere in your system, and this does not make sense when you state the pool is looking great.

[Westy]

I did have an issue with dirt in the pool when refilling after CYA reduction drain/refill cycle. We have a well and I got some dirt/sediment into the pool. There are no visible remains of any of this in the pool or skimmer or filter (cartridge), but I'm wondering the same thing, why is the chlorine I'm adding INSTANTLY combining? The more Cl I add, the higher my TC level goes, with FC staying at zero.

[dynamictiger]

Well water could be the issue. It may contain some reducdant that is consuming the chlorine or it may just be complexing the test result.

Are you using OTO or DPD test method (drops or tablets)?

Is the FAC test actually being bleached so you think you have 0 mg/l when in fact it is very high?

Try diluting a sample of pool water with distilled water about 1/5 pool water to distilled water and try testing the resulting mixture for free chlorine.

HTH

[Westy]

Problems continue! I checked the reduction of CYA with test strips. I purchased some new CYA reagent yesterday and did drop test with Taylor test kit and found CYA still well over 100!. This AFTER 3 drain/refill cycles of half the pool water. Maybe this has something to do with my Cl problems? Free chlorine test yesterday was still at zero, TC at 1-2. The math on the CYA levels just doesn't make sense. With my starting CYA levels, 3 cycles should have reduced CYA to about 30-40. I have not added stabilized Cl to pool since beginning the drain/refill. What is odd is that the test strips showed a gradual progression in CYA downward as I did the cycle. They currently show about 30 ppm. In other words, the test strips showed a reduction in CYA that matched the drain/refil cycle that I did. The initial reading before the cycle on the test strips was about 300 ppm. Is there some interference with the CYA drop test that is showing a false positive? I'm about ready to fill pool with dirt and plant a garden!

[dynamictiger]

Wendy if you can please get a sample tested at a pool store at least then we can elimnate the test strips as an error.

Let us know the outcome.

[Westy]

Wendy if you can please get a sample tested at a pool store at least then we can elimnate the test strips as an error.

Let us know the outcome.

Replaced all test kit reagents and did 3 more drain/refill cycles....success! Have CYA levels in the 40's and holding FC nicely. I must have started with CYA levels in the 7-800 ppm range.