How bad is high pH and Alk in a plastic pool?

marietta · Postby **marietta** » Sun 19 Jun, 2011 14:27

How important is it to get / keep the pH and alkalinity down? We've had our pool (15 x 3.5 above ground walmart with the skimmer/pump on the side - 4000 gal) up for 10 days and are on our 2nd container of pH down. It's still pH 8.4+ and alkalinity 240+. Hardness is 0, cyanuric acid 40 and free Cl is 2 right now. Clorine (both free and total)tends to be good until I take the cover off. Then it gets down to 0 or .5 when we get done swimming for an hour or so and recover. The clorine tabs that go in the filter don't seam to do anything, but if I add 18 oz of bleach and run the pump for a few hours I get both up to 2 the next day, until we open it and get in and then it's back to 0ish again. I can live with this routine, but am afraid of damaging something with the pH, Alk & hardness being so far off. (The water is super clear - just like it came from the tap)

Thank you for any comments / help!

Chris
Marietta, OK - Several 100+ degree days and counting!

Postby **chem geek** » Sun 19 Jun, 2011 18:49

I doubt the hardness is truly zero. You need to get a better test kit. However, if the Calcium Hardness (CH) is low, then even with the high TA and pH the risk for scaling is low. The main problem is the high pH which will not be great for the eyes if it gets too high. Also, if you have metal ions in the water, then they can stain at high pH (and TA).

So while not a disaster for your particular pool, you can lower the TA by adding acid and can accelerate the process (if you want) by following the procedure described in this post. Just be sure to add acid slowly over a return flow with the pump running and then brush the side and bottom lightly in the area where you added it to ensure thorough mixing.

marietta · Postby **marietta** » Wed 22 Jun, 2011 15:00

Thank you. I was worried that I was in big trouble with the levels I was at and ruining my pool! I went thru another bucket of acid and the ph is now around 7. It's airating now. Alk is still high (240+). I guess I should get more acid, but the water never bothered my eyes before and now it seems to. Might be my imagination thinking about all the acid I've put in or maybe I'm just used to high pH in water after living with it so long. :-)

Need to order a 3rd test kit. HTH's Cl / Br / pH with the drops does not match results from their 6 way test strips and that's all Walmart carries... :crazy:

Postby **chem geek** » Wed 22 Jun, 2011 21:03

The best test kit to get is either the Taylor K-2006 or the TFTestkits TF-100 with the latter kit having a much greater volume of reagents you use the most.