1. By 2nd stage skimmer, I assume you mean the pump strainer basket? Have you cleaned that?

2. Do you have a main drain?

3. What is a "moss filter"?

4. Are your pipes plastic or metal? If metal, iron or copper?

5. Is the debris just leaves, or is it leaves + sticks?

+ Turn off the heater till the pool is clean. Warm water grows algae MUCH better, and you don't want that.

+ If you have water flow in the skimmer, fill it up with chlorine tabs. Chlorine will gradually 'eat up' the leaves. Do NOT do this is there's no water flow.