So a little background, I have a 25000 gallon pool and spa. One of the issues in the pool that I believe causes a lot of problems is that there is no popups in the water other than on the stairs so the water does not circulate much even if the vaccum is on and running in the pool. For the past 6 months, I have been getting both black and green algae and they continuously keep coming back. I keep chlorine in the floater at all times but I don't think it works well enough. I typically go to my pool store (Leslies), which I know is usually a mistake, for advice and I am told to scrub the black algae with a chlorine tablet whenever it shows up and then shock the pool, which works for a couple weeks and then spots start showing up again within a couple weeks and I typically treat the green algae with shock and brushing. the pool store hasnt been much help as they tell me I need to buy like $200 of phosphate remover every time I go and my problem would be solved, which I don't believe is true.
What would be the best way to approach this problem? I have test strips that I use to check the levels and I have just shocked the pool and scrubbed all the black algae spots. It is getting reaaally annoying having to spend so much time trying to get rid of this algae.
Any help would be greatly appreciated.