I have small brownish, gritty stains on my walls and was told I might have scale, this thread. I also noticed my plaster getting whiter. I lowered my PH to 7.0-7.2 and brushed for a couple of weeks and that seemed to make my plaster look better ( I was able to see the colored specs in my Diamond Brite plaster). One month later, my PH drifted up to 7.8 for no more than two days and my plaster got whitish agian. I called Diamond Brite (SMG) and they said it was scale deposits and I should do a "no drain acid wash" and emailed me procedures.
I'm a little worried of the amount of muratic acid they are telling me to add to my water, so I will post the directions and let you guys tell me if you think this is safe. Since this is coming from the manafacture, I am assuming it should not hurt my plaster but they did mention to remove all metal parts/equip from the pool and any heaters because they can turn black or metal equipment in the circulation flow.
I have kept my water balanced, (6months)- CL 2-6, TA 70-90, CYA as low as 25-50, CH was at 180 for 1 month I added calcium and it went to 240 and it held for 3 months. When I first started with the stains I lowered my PH and started brushing and dust was coming up. 2 weeks later CH jumped to 460 where it held for 3 weeks. I started draining and let the heavy rain refill the pool and CH is at 350. I add 1.5 gal avg of acid weekly to fight ph rise.
SMG suggests I add 1qt of sequestering agent for evey 10,000 gals, balance water, remove all metals parts/equip from pool, turn filtration on 24 hrs, add .5gl acid for every 1,000 gl of water (12 gals of acid for my pool), brush twice a day until pool finish looks best (should take 2.5-3 days) and bring back PH to 7.2-7.6 slowly.
Sorry for long post, but what do you guys think? Also, would my Colorlogic S/S faceplate ring get ruined (is that considered metal)?