Unfortunately, your problem is not uncommon. Fortunately, we're here.

1. Stop using everything the pool store can think of -- you may ALREADY have problems due to incompatible chemicals. Do NOT use any more algaecides, especially copper based ones.

2. Buy some DE powder -- a 10# bag is plenty -- and add a coffee can full to your skimmer, while the pump is running. Then, watch the inlet where water from the filter returns to the pool. If the return water gets cloudy with DE powder . . . your filter needs service. Most likely, it simply needs more sand. Fix this pronto; you will not be able clear an algae filled pool with a non-working filter.

But, if the DE does not return to the pool, that's great: the DE will help filter out fine algae particles that would otherwise go THROUGH the sand bed in the filter.

3. Purchase a cheap local OTO kit (yellow / red drops), and test your pool. You want your chlorine level in the DARK yellow range, above what the kit shows.

4. Read the "Best Guess" page -- linked in my blue signature block -- then go get a CYA test, so you can get a rough idea of what chlorine level you SHOULD be maintaining.

5. Go to the Test Kit info page (blue block again) and follow links to Amazon so you can get a K2006 kit, and find out what your CYA level actually is, and can measure the chlorine level you need. NOTE: So far as we know, K2006 kits are not sold locally, anywhere in the US. Pool dealers find it hard to get enthusiastic about product that replace them.

6. Post info on DE filter test results, OTO test results and current pool condition, once you have that info.

7. Run your filter 24/7 if you are not already doing so.