Hello, I have been studying the website and forums for about a week. I have very dark green algae and cannot see the bottom of the pool. I also have lots of white scale. In the beginning I used a lot of algae treatment, shock and First Aid from the pool store. I have been brushing and vacuuming daily. It will clear some and then go back again. Then I discovered your website and made a trip to Walmart and the pool store yesterday.

My pool is a fiberglass Roman style pool with a built on tiled fountain. 15,000 gallons, installed in 2005. It runs a Hayward 1.5 hp 24" sand filter pump. The pump is filled with DE. We have had an Aqua Logic AQL-P4 salt system with a T-CELL-15. We have had constant problems with the Aqua Logic failing and I have been able to fix it. This time it is beyond repair and the cell is worn out. I have ordered a replacement cell. After putting that in, I should be able to verify if the board is bad again. If so I plan to replace the board. I didn't know the system had failed until the pool turned green. So currently we are running it as a regular chlorinated pool.

I am using test strips to measure. I have bought the test kit from Amazon through the link on your site. It is supposed to be here tomorrow.

Last night my readings were:
TH 500, TC 0, FC 0, pH 8.4, TA 120, CYA 15. I added 311 oz bleach, 35 oz muradic acid, and polyquat algecide.

This morning my readings are TH 250, TC 5, FC 10, pH 7.2, TA 80, CYA 0. I added 5 1/4 cup Borax.

I'm finding some confusing info and have a question. The pool calculator says to add baking soda and CYA. On the pool start up problems page in poolsolutions.com it says to not add any stablizer until the pool is clear and can hold 2 ppm residual chlorine overnight. In some other places it says to not let your stabilizer go below 30.

Should I add CYA? Do I need to add baking soda along with the Borax as the calculator suggests?

What level CYA should I maintain while getting rid of the algae?

Thank you,
Michael

Fiberglass, 15k gallons
Hayward 1.5 hp 24” sand filter refilled with DE