PH always low

The PH in our always seems to be low. We always have our water tested at the Pool store. They recommend shock and soda ash to increase the PH. Then it drifts back down, shock and soda ash. But this year We have added enough Shock and Soda Ash to fill in the pool and the PH is still off the chart. Chlorine fluctuates from high to low. and 3 times we have had algae blooms. My question is would Borax help stabilize the PH and chlorine use? Here are the results from the last water testing at the pool store.

FAC- 0
TAC- 4
CH- 125
CYA- 100
TA- 30
COPPER- 0
IRON- 0
PHOSPHATES- recommendation - Shock and 20 lbs of Soda Ash. (HELP I am going broke at the pool store.....lol)

HOME TEST the PH was not even on the scale......

I'm not positive, but I'll be willing to bet the "shock" they sold you was sodium dichlor--which actually is acidic and will drive your pH downward. Adding Borax will get the pH up into the 7.0-8.0 range, where it belongs--and this is a critical thing...if your pH is lower than 7.0, your water is very acidic and will damage your liner, if you have a liner pool. You need to get a good reading for pH, and start adding Borax immediately to get the pH back up above 7.0. When your pH comes up, it is likely that your TA will come up, as well. Do you use trichlor tabs for chlorination? They are also acidic and will drive pH down. They also will substantially increase your CYA, and I see that it is very high,.

Your chlorine fluctuation and algae blooms are likely because you're not keeping your chlorine high enough to keep the algae gone, and so you're continually fighting an algae bloom (you're definitely fighting something with a FC of 0 and a CC of 4). With a CYA of 100, you need to be keeping your chlorine at an absolute minimum of 8 ppm, but now that something's in the water you need to shock the pool. For a CYA of 100, that shock level means you need to raise your chlorine to 25 ppm, and hold it there by testing and adding more chlorine, until you can go overnight without losing more than 1 ppm of chlorine. When you get to that point, you can let the chlorine drift back down, but not below 8 ppm.

Ignore the phosphate level--it's not really relevant to your situation, and it's just another way for the pool store to convince you to buy something you don't need.

Welcome to the forum!

Thanks Janet - good post.

Mag, you need
1. Reliable testing, particularly of CYA and chlorine levels.

2. Unless you want to drain and refill, you will need DPD-FAS chlorine testing (= K2006 testkit, which is NOT available locally!)

3. To buy 6 boxes of borax, and start adding them, 1 box per 10K gallons, SLOWLY to the skimmer, pump running, every 2 hours, till your pH is above 7.2

4. To read the Best Guess page, also linked, so you can understand how CYA levels must be related to chlorine levels.


Here the test kit links. If you get the HTH at Walmart (you can check local stock online) you'll STILL need the K2006, because the HTH kit only has the OTO test. Getting both is a a good idea, since the OTO test gives you a cheap and quick test; and the K2006 will give you accurate chlorine measurements at the high levels require by your CYA (stabilizer) level.