Unable to reduce PH value of pool


New member
Jul 24, 2010

This is my first post to this forum, and hope someone is able to help me with my odd problem.

It all started with some dark stains in the corners of my pool, that I simply could not get rid of (yes probably accured because of proper maintenance in the first place), even using shock and algee remover did not help, so I was told taht I may be suffering from calcium surface, and the calcium would have imbedded the algee, which is why its impossible to scrub off. So I was adviced to lower the PH value to 6.0 for 3 days, and scrub daily and it should disolve the calcium and I should have the stains removed.. and if I swipe my hand along the side of the pool, I do get white stains on my hand.. I the procedure had begun... However I have hit a wall.. I simply can not get the PH value below 6.5!! I have put about 9 kg (~20 lb) im smaller doses over 2 days, but it does not change the PH Value...

Im starting to doubt my measiring device as it can simply not be true (using AquaChek), but it seems to be consistant. it reads:
Clorine: 1
PH: 6.5
Alk: 35

As for what I can read, the Alk is very low, and I should se large change in PH value, but its rock solid at 6.5.

Any help is much appriciated.


New member
Jul 24, 2010
And forgot to say the pool size is 30.000 liters

30 (cubic meters) = 1059.44 cubic feet


TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
Can you describe what the stains feel like when your touch them: smooth, slimy, rough? Also what color are they?

It would also be good if you could post a complete set of test results, notably CH and CYA.

And, what kind of surface do you have: plaster, pebble, vinyl, fiberglass, etc?


Mod Squad
TFP Expert
Apr 4, 2007
SW Indiana
Welcome to TFP.

How are you testing your pH? Your kit may bottom out at 6.5, meaning your pH is lower than that.

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