Sounds like you may be trying to filter live algae with a DE filter. That will not work -- live algae stops up DE almost instantly.

1. Get a OTO/phenol red test kit, locally (Walmart, Kmart, Lowes, etc.)

2. If you haven't already done so, remove all the physical debris (leaves, branches, etc.) from the pool. There's no point in trying clean it up till that's done.

3. Describe your pool: concrete/vinyl/FG; pump make/model; filter make/model, pool dimensions.