Cant seem to get rid of CC

[Ltingcang]

My initial chemistry results : pool size 17000 gals FC 1 TC 2 CYA 40 other results with in acceptable levels.

I shocked with 3 lbs calhypo 48% next day reading was FC 3 TC 4 . Shocked again with 4 lbs Cal hypo 56.8%. Next day reading FC 17 TC 18. When I added chlorine last night i ran the pump overnight at low setting ( i have dual setting pump 2HP pump,3 month old pool.high setting runs with clear O3ozonizer)...back up..we run our pump at least 8hrs/24 hrs 4hrs high setting 4hrs low.now the pool water is very clear...but CC is still 1...im using the TF 100 test kit.

pls help!

[BigDave]

...high setting runs with clear O3ozonizer)...
I know that Ozone creates chlorine demand. Perhaps PoolDoc or chem geek will offer advice regarding whether or not ozone creates Combined Chlorine.

Generally we don't advise anyone use Ozone in an outdoor pool.

[Ltingcang]

Should I turn off my ozone generator then? Actually whenever I shock the pool i dont turn on the ozone.20 hrs after i shocked the pool FC 7 TC 7.5 CC .5. Should I shock the pool again?

[chem geek]

If there is actual ozone residual in the pool, then it will measure as Combined Chlorine (CC). This is because ozone doesn't directly react with DPD for the FC portion of the test (at least not much), but it most certainly oxidizes iodide to iodine when you add the R-0003 reagent during the CC part of the test.

Get rid of your ozonator. It's pointless in an outdoor residential low-bather load pool exposed to sunlight.

[PoolDoc]

Just as a follow-up -- in many cases, you don't actually have to REMOVE the ozonator; you just need to turn it off. You should also close / crimp / or otherwise block the point where air + ozone enters your system.

However, if you have a venturi to pull air into the system, you will want to remove that eventually, unless you can fully bypass it. Venturis waste a LOT of pump energy.

[Ltingcang]

Thank you for your responses.Its disappointing to learn that I spent for the ozonator and yet its useless. I hope with the ozonator off,and with subsequent shocking,my CC will finally be 0.

[PoolDoc]

It's not so much a matter of shocking, as it is maintaining consistent, appropriate levels of chlorine. You must read the "Best Guess" page, linked in my signature, to understand what we mean . . . and why.

And you must have a method accurately testing your CYA levels, so you need a Taylor K2006 (from Amazon, since they aren't available locally). Again, there's a link in my signature.

Finally, if you have a pool cover, you must leave it off during some sunny hours, at least several times per week. The chloramines that typically form in pools are not the simple ones described in pool books or by pool dealers, but complex ones that form from the reaction of chlorine with urine or lotions. Chlorine + sunlight breaks these down much, MUCH more effectively than chlorine alone. Also, chloramines leave the pool as a gas -- and they can't do that, if the pool has a gas impermeable cover.

Good luck. We're sorry you got 'pool-stored' like so many others before you; we can't fix that, but we can help you avoid having it happen again.

[PoolDoc]

One more thing: avoid blended chlorines! What they are blended with not only dilutes them, but can cause problems. Cal hypo should have an active chlorine level of 68% or higher; dichlor should be 55% or higher. Products with lower active chlorine levels are blended.