Very Low T.A. and dropping overnight

[monkeyhanger]

hi All, new to the forum and looking fir some help.
We have a 25mx10m pool (school) 0.8m shallow to 1.8 deep
The problem we have is constant low T.A.struggle to keep it above 40, our P.H. is between 7.2 and7.4 so no problem there all othe rparemeters are fine also, we can get it to 90 with 25kg of sodium bicarb added at intervals throughout the day but overnight will drop to 40 again.
Using Sodium hypochlorite and Hydrochloric Acid in a soft water area. UK pool.
We`ve tried reducing chlorine set level ,dosing with dosing units disabled to mention one or two thing but limited success.
The source water is 110 at tap
Any help tips would be greatly appreciated.


Andy

[Denniswiseman]

Hi Andy
If you have a stable pH then a low TA is acceptable. Or are you adjusting it
You seem to have the recommended chemicals which is what I use as well
How have you been using them
Muriatic acid (hydrochloric acid) to lower pH and TA
Bicarbonate of soda to raise TA
Aeration will raise pH only
Cyanuric acid (stabilisor) stabilise's the chlorine
How are you testing the water, strips and pool stores are widely inaccurate also what is your CYA
What is the pool construction and is it indoors or outdoors

[monkeyhanger]

The pool is below ground indoor and ceramic tiled,we have photometer for testing water, the pool has been running around 18 months -2 yrs. My worry about low T.A. is that the floculant needs a T.A. above 75 to work, we use PAC to coagulate cryptosparidia at the low levels we are achieving the floc is wasted and the risk of a crypto outbreak is high, so far all test are fine but the risk is there.

[Denniswiseman]

Hi Andy
I've sent you a private message as there is an email to a more professional person who may be able to help you