21000 Gal - Fiberglass - Cartridge Filter - Bay Area


Sep 7, 2021
San Ramon, CA
Hello all,

I have an in-ground 20,944 Gal Fiberglass pool. I love using it in the summer, However I do not love all the maintenance it requires. I have hired professional services however it seems that even they could not keep the pool clear. It is currently algae ridden again (the third time this summer) It was only until perusing this site that I have discovered why that may be. My CYA is about 80 ppm. No wonder I have had to keep adding gallon upon gallon of chlorine to keep it at an acceptable level. I am currently draining about a quarter of the pool so I can lower that before slamming. I also have been flooding the pool with algaecides, no wonder there is elevated copper in the pool and my roommates blonde hair turns green when she goes swimming. I am excited to finally get the correct info to keep this pool clear and not waste money on useless products.

here are a few more details about the pool.

-20944 gallon
-Pentair CCP420 cartridge filter
-1 hp pump

I look forward to any advice anyone has for me or any recommendations for products.


Gold Supporter
LifeTime Supporter
TFP Guide
Jul 3, 2013
Southern OK
Pool Size
Salt Water Generator
SWG Type
CircuPool SJ-40
Welcome to TFP :)

You may want to empty the pool to get all the copper/metal out, that is the only way you can get rid of it... It will help by getting rid of some of the water though...

My recommendation for products is liquid chlorine and muriatic acid.. its all you need.. :)

The next best thing in life is a salt water generator but we can talk about that after your done with the SLAM Process What test kit did you get?

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
Texas, San Antonio/Marion, South-Central Area
Pool Size
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
I agree with Casey. Exchange as much water as you can now to remove copper which will also take care of the CYA. Copper is the most obtrusive with the side effects. No more algaecides unless it's a Polyquat 60 product (non-copper). Even then, once you get your FC and CYA properly balanced, you may never use an algaecide again. Because you have a FG pool though, you might find yourself doing many smaller exchanges to avoid pop-out. Be careful.