chlorine vanishes

[CharlieB]

I had my water tested to back up my tests this morning. confirmed FC 3.9%, ph 7.0, TA 34, cya 100, total hardness 133. chlorine is now holding steady. bought 25 lbs sodium bicarbonate to raise the TA. water is now crystal clear. have not useen any more signs of the yellow dust on the steps for several days.

i guess it was the excessive rain.....

[PoolDoc]

i guess it was the excessive rain.....

The only reason rain causes algae is that it causes pool owners to ignore their pools. Chlorine is just as effective at destroying algae spores when it's raining, as it is when the sun is shining!

[CharlieB]

i'm through....

[PoolDoc]

i'm through....

????

[kelemvor]

I had my water tested to back up my tests this morning. confirmed FC 3.9%, ph 7.0, TA 34, cya 100, total hardness 133. chlorine is now holding steady. bought 25 lbs sodium bicarbonate to raise the TA. water is now crystal clear. have not useen any more signs of the yellow dust on the steps for several days.

i guess it was the excessive rain.....

It's worth mentioning that with a CYA of 100 you need your chlorine to be between 8 and 15 to be effective. Also, most (all?) tests do not register above 100 for CYA so your cya level could be significantly higher. If you just drained off 6" and replaced it with rain, and you're still registering 100, it's a safe bet it's well above. I would stop using the trichlor pucks (these add CYA to the water) and try to figure out what your real cya level is. AFAIK there is only one way to actually reduce CYA levels and unfortunately that is do a partial drain and refill with fresh. Alternatively you can try to compensate for the high cya by maintaining correspondingly high chlorine levels.

To test for CYA > 100 with the Taylor kit you should be able to mix your pool water sample 50/50 with fresh distilled water, then run the CYA test and multiply the result by two; assuming it's not over 200 that should get you a reading you can work with.