Test Check

[CarlD]

Thanks! I have a 25k gunnite pool. I've always shocked with liquid chlorine, never even tried cal-hypo. Our source water my be high in both TA and pH. Maybe I should test that to get a baseline?



I don't either, but it's always a struggle keeping it down. I'm dropping it tonight to 7.0 - 7.2 but in a few days I'm sure it will raise back up. It threw me for a loop when Home Depot cut the strength of acid in half without any clue.



Maybe that's it. I did have to deal with algae when I found my CYA so low (then I raised it to 40) and the sun so hot that chlorine wouldn't last even for a day. Do you think the floater technique will work to keep it in check and raise the CYA?

Thanks!

Checking your fill water is always an excellent idea--ours used to have a t/a of 180.

Lowering T/A is done indirectly. T/A is linked to pH. Not only is it a pH buffer, but as pH rises and falls, T/A rises and falls with it. So....you have to lower the T/A relative to the pH. The way to do this is to lower the pH and bring the T/A down with it.

Then there has to be a way to raise pH without T/A going up again--Borax won't do it, Soda Ash won't do. The trick is aeration.

Aeration sounds fancy but it's not. Leaving your pool uncovered will cause some aeration and pH increase, but lots of splashing kids or a fountain causes it to increase the pH much faster. You can point the return jet at the surface too, that helps. I won't go into the chemistry of the gassing off--in part because I only partially understand it myself.

When pH rises from aeration, you then add acid again to lower it back to 7.0, each time measuring your T/A after you aerate it back up. When the T/A is where you want, it you stop aerating. It's a racheting process.

Since you are having troubles keeping pH down, you could try getting the T/A down to the 80-100 range--100 max--and see if that helps stabilize it. Don't start using Cal-Hypo, but stick with liquid bleach/chlorine...I thought with your CH # you might be since pH was rising to.

If you want to raise your CYA and are fighting rising pH, then Tri-Chlor pucks are an excellent way to do it. Be sure to check CYA every week though and stop using them when you hit your CYA target.

aylad, my fellow mod down in Louisiana, likes to run a much higher CYA than we Northernors, Poconos and myself, do. That's because she faces far more intense sun and heat on a regular basis and it's just easier and cheaper to run the pool with a CYA of 70 or 80 and maintain a residual FC level of 5 to 10 ppm. She actually uses less chlorine that way.

Your K2006-C is really not any different than the older PS-232 and PS-233 kits sold by PoolSolutions--just organized a little differently--and you have the acid and base demand tests as well. It's all Taylor reagents anyway.

Hope this all helps.