when do you send in the recyclers?? with attacking fleets or after the hit?? and what happens when you try to pick up debris from a planet that has defending fleet on it??

You launch the recyclers as a separate harvest mission. They're slower, so if it's critical, you may want to launch the recyclers before the attack.

They go to the debris field, not the planet, so they are unaffected by fleet or defenses at the planet or nearby moon.

Thanks Mintaka..

So, the recyclers pick up the debis and what do they do with it? Make it good metal and crystal? Keep it in their cargo?

Return the metal and crystal to the deploying planet.