I have just bought a house with pool. The pool is about 8 years old. When we moved in the water was extremely cloudy and green from algea. The pool PH was very low (did not register any color at all on using the dropper test kit with new chemicals). I have managed to kill off the algea using high doses of chlorine and a lot of scrubbing. The water is now reasonably clean but I cannot get the PH level up. The pool volume is about 75KL and I have added 6 Kilo of soda ash over a period of a week with only a slight rise in the PH (chlorine level in the normal range). From researching the net I think a possible cause could be the total alkaline level, but have not measured this yet.

Any suggestions?

Yes, high alkaline levels act as a pH stabilizer; alkaline "locks" in pH making it hard to adjust (but great for pool management since we do not need to adjust pH often). Any good testing kit (litmus strips) will include alkaline testing. Also, with very low pH, more soda ash may be required (6kg is not that much).

Gil

Yes, high alkaline levels act as a pH stabilizer; alkaline "locks" in pH making it hard to adjust (but great for pool management since we do not need to adjust pH often). Any good testing kit (litmus strips) will include alkaline testing. Also, with very low pH, more soda ash may be required (6kg is not that much).

Gil

Thanks for that Gil. All the pool shops I spoke with indicated that 6 Kg was way too much but I suspected not as the pool has not been looked after. The water has I suspect been acidic for some time as most of the grout has been eaten away. Have a leak to find as well.

Actually, for 75,000 liters, you will need about 3,000grams (3kg) to raise pH by 1.0. Assuming your pH is about 4.0 to raise it by 3 (to reach 7.0) you would need at least 10kg. Standard pool water treatment tables are widely available on the net. Simply plug in your volume / desired pH level, and see the required volume of soda ash.

Before doing anything though, I would take a bucket of the pool water and adjusts its pH independently using a small quantity of soda ash. Reason being, I would want to make sure that nothing else is going on (e.g., high chlorine bleaching out your pH readings) before dumping all that soda ash in the pool. If you can raise the pH in the bucket of water, then I would say you can also do it in the pool. A digital testor will show you readings in real time though, making it far more accurate than litmus strips.

Gil

Thanks for the help Gil.

PH and clorine levels are now under control.

Actually, for 75,000 liters, you will need about 3,000grams (3kg) to raise pH by 1.0. Assuming your pH is about 4.0 to raise it by 3 (to reach 7.0) you would need at least 10kg. Standard pool water treatment tables are widely available on the net. Simply plug in your volume / desired pH level, and see the required volume of soda ash.

Before doing anything though, I would take a bucket of the pool water and adjusts its pH independently using a small quantity of soda ash. Reason being, I would want to make sure that nothing else is going on (e.g., high chlorine bleaching out your pH readings) before dumping all that soda ash in the pool. If you can raise the pH in the bucket of water, then I would say you can also do it in the pool. A digital testor will show you readings in real time though, making it far more accurate than litmus strips.

Gil

Thanks from me also. My PH wasn't even registering. Did the bucket test with a cup of soda ash...and whammo! It was off the charts. So, have been slowly adding day by day and now am almost to normal. :jap:

Ye ole bucket test. Its great also for figuring out how fast a pool is leaking...

RE pH its great to see this increased awareness. We love re-grouting business, but after several hundred pools its getting a bit old now...proper pH is the single most important water chemistry parameter there is - it prevents damage, makes the pool safe, and signficantly impacts the role of chlorine.

Gil

Ye ole bucket test. Its great also for figuring out how fast a pool is leaking...

RE pH its great to see this increased awareness. We love re-grouting business, but after several hundred pools its getting a bit old now...proper pH is the single most important water chemistry parameter there is - it prevents damage, makes the pool safe, and signficantly impacts the role of chlorine.

Gil

No Kidding! I think the previous owner had left the pool acidic for some time. Had a good swim around my pool with a half mask and there is literally no grout left at all. I even managed to lift a tile off while vacuming. Looks like a big job once the weather cools down!

If you ar going to refurbish a pool, don't even think of using standard domestic tile adhesive and grout. Using the slightly more expensive special products for pools will save you more agony later on. Some pool professionals don't bother because they are speculating on repeat business a couple of years later to regrout your pool. As always, try to avoid purchasing any pool products at the often highly inflated prices practiced by many pool shops. The products, as well as most pool accessories, are widely available in Thailand from other building supplies outlets, at much lower prices.