Filter Problem?

[Watermom]

Have you backwashed your filter lately? You shouldn't need to replace your sand. I'm on my 9th summer with the same sand with no problems. Some people have had theirs for even longer with no problems. You might try adding a little DE to your filter to help filter out the smaller stuff. There is a "sticky" at the top of this forum with more info about that. Sometimes when you have a lot of algae, it is a good idea to vac to waste instead of to the filter. You might want to post a complete set of current testing numbers.

[blue_steel]

I agree with watermom. Always vacuum loose algae to waste.
Also, you can add a clarifier. It will make the fine particles clump together. WalMart has HTH for around $11 per gallon (vs. $20+ at the pool store). Then when you vacuum, the clumps will get caught in the filter and flushed away when you backwash.