Do NOT put it directly into the filters!

Instead, put about 2 quarts -- 1/2 gallon -- of DE into a skimmer while the pump is ON. Then, go watch the return jet closest to the filters. If DE shoots back into the pool, your filters need service. If not, the DE will help filter fine particles, but will likely cause the pump pressure to rise much more quickly, so you may need to backwash in much less time than usual.

You'll still need the kits . . .

When you wrote that the "pool just does not get clear", did you mean just this spring, or normally?

Also, what chemicals and processes have you used trying to clear the pool this spring?