Low PH and TA

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.

Low PH and TA

Postby dbrook » Mon 05 May, 2008 13:28

I have an 18' x4' Intex Pool. At beginning of spring, to reopen pool, (we had a small amount of algae on bottom of pool) I shocked pool and then added algaecide, then brushed walls, kept pump running, continously cleaning filter for a couple of days. I drained some of the water from bottom with a sump pump and added fresh water using our city water. At first the water was clear but a little cloudy, now its as clear as can be but doesn't have the sparkle that it used to have. (If it makes any difference, I have a Polysack canopy that is supposed to cut the harmful raysand reduce the Algae, over it) I use a 4 lb chlorine floater with the notches cut a 5,000 gals and have done this for 4 years now with absolutely no problems. For the last 2 weeks I have had a problem trying to get the PH and TA increased. My test strips show them both as very low and the Chlorine level is a little high and Hardness OK. I bought Borax and have added a 4 lb box and have added Ph Increaser and 2 lbs of Baking Soda, cleaning my filter and running my pump 24 hrs a day. I added the Borax to the skimmer, slowly. (I hope that was the way to add it) I am running the fountain sprayer that is installed in the pool aimed at the middle depth of the pool for circulation. I have tested the pool every day 2 times a day and I still have a very low Ph reading. Please help!
I am lost at what to do next. The grandkids want to swim but I won't allow it until the water is in balance. I have owned a 24'x36' gunite pool, a 28'
x6' round vinyl inground pool that I maintained, but this little pool has whipped me. Thanks for your help.

chem geek
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Low PH and TA

Postby chem geek » Mon 05 May, 2008 14:40

If the pool is really 5000 gallons (if it's 18x4x4 then that's more like 2100 gallons), then the amounts you are adding are not enough if the pH is below 6.0 and the TA is above 30. Get yourself a good test kit, the Taylor K-2006 you can get at a good online price here or the TF100 test kit from tftestkits(dot)com here with the latter having 36% more volume of reagents so comparably priced "per test". Test strips are not very accurate for most tests.

If you post accurate pH, TA, CYA numbers as well as pool volume in gallons, then I can tell you how much you need to add of what product. For an approximation, you can use The Pool Calculator. In the meantime, you can just add more pH Up product (which is identical to Arm & Hammer Super Washing Soda; careful: not the laundry detergent) if both pH and TA are low or 20 Mule Team Borax if mostly pH is low.

It sounds like you've been using Trichlor tabs/pucks in a feeder. These are highly acidic, especially when accounting for chlorine consumption which is also acidic. The low pH can damage vinyl pools as well as equipment (copper heat exchangers, pump seals, etc.). Your Cyanuric Acid (CYA) levels may also be very high as for every 10 ppm FC added by Trichlor, it also adds 6 ppm to CYA. You may need to use a supplemental algaecide (PolyQuat 60 or a phosphate remover) to keep algae from forming unless you lower the CYA level (if it's high).


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