Out of control PH level in SWG pool

[Saltwater-Taffy309]

I have a SWG pool and I can't keep the PH level under control. I add about 2 pints or so of muriatic acid about every other day. It effectively lowers the PH level, sometimes down to 7.2 or 7.4 but it only takes a day or two to get back up to 8.0+

Total Alkalinity is currently at 90. It was at about 110-120 before I started adding muriatic acid (been adding it for weeks now).

Salt level : 3600 ppm
CYA : 70
FC : 4-5

Is this just a consequence of a SWG pool or something going on?

 

[wireform]

Are you dealing with new plaster then that may be its norm for the next while but the more you knock it down drastically the faster it'll pop up. Aim for higher in the 7 range and find a sweeter spot it'll stay for longer and see if there's less of a rise shoot.
On another note your FC is low period. A CYA of 70 needs a target 5-10 and closer to the high end is recommended so you don't end up with a slam surprise which at 70 isn't easy.

 

[pjt]

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