Charlie:

If you need to use a phosphate remover constantly, something else is wrong with your pool chemistry. Most of us NEVER use it and rarely, if ever, have an algae problem. I've never measured my phosphates and have had very few algae blooms over the years, and never had a major one, ever.

Phosphate Removers are the latest gimick at pool stores to get people to spend money constantly on something they can't get anywhere else. They measure your water and say "Oh, your phosphate level is high--you need this chemical--every week!" For a while it was "Total Dissolved Solids". A couple of years ago it was the Nature2 erosion systems. An ongoing one is selling calcium to vinyl pool owners (calcium is useless in a vinyl pool). If one in a thousand pools actually needs a phosphate remover, that's a lot.

I THINK you said you are using an SWG. With your CYA at 80 and your FC at 2.5 and your T/A at 120 and a pH of 8, I'm not surprised you are fighting algae. If you don't have an SWG, than I'd be shocked if you did NOT have an algae problem with those numbers.

1) Let's start at the end: pH=8. This kills most of your chlorine's effectiveness. At even 7.8, chlorine is far less effective at killing stuff than at 7.2 or 7.3. So you MUST get your pH under control. This alone may solve your algae problem, ESPECIALLY if you have an SWG.

2) Your FC is too low for your CYA--it's 2.5 and your CYA is 80. Normally, you need an FC of 5 to 10 for that CYA or you'll get algae. However, if you have an SWG, you may be OK at 2.5, but 3.0 is probably safer--I'm not the SWG expert here--check the owner's manual.

3) Alternatively, you can lower your CYA to between 30 and 50 and keep your FC between 3 and 6. But if you have an SWG, your CYA level is probably correct, but you still need to set the SWG to a higher FC level.

4) Your T/A is fine--if you don't have an SWG. If you do, you should keep it lower--around 80-90.

Take all these steps and you can stop wasting your hard-earned money on the phosphate removers.