Scale on Sides of Fiberglass Pool

[RKF]

FC: 7
PH: 7.4
TA: 50
CH: 150
11,000 gallons SWG

I have been fighting scale on the sides of my SWG fiberglass pool for a year now. I have been trying to keep the TA and the CH low in hopes that the water would reclaim the minerals from the sides of the pool. Obviously this isn't working. Any help with this problem is greatly appreciated.

 

[Texas Splash]

Welcome to TFP! Perhaps the most imprtant thing to do at this point is confirm .... is the white you are seeing actually scale (calcium)? Often we assume it is (I did in my chalky pool) but larer believe it wasn't scale but a form of oxidation. So I would first try to check. You can either try to scrape a sample off the walls, place in a pile, then pour some muriatic acid on it to see if it fizzles, or lower the water level a bit and put acid directly on the effected areas. If it doesn't fizzle, I'm guessing it's a form of oxidation.

Your CH, TA, and pH numbers are already on the low end, so I wouldn't go any lower as that will just make the water more aggressive. Much as in my case, it may only make the discoloration worse if it's oxidation.