In sump Refug question

[clermont]

Okay, so last night I am working around in the sump and I start to think. How are the copepods getting to my display from the fuge to the display tank through my pump?
I have an Eheim pump and it has this Foam protector all around the intake so if sand particles and such cant get through this, will the copepods be able to?
I worry about my mandarin having enough food and that really is the reason that I started up the Fuge so if anybody knows if I should remove this protective foam or know that copepods can actually find there way through it?
On a good note I purchased a Jeboa power head recently and the feed mode has helped me to try to train the mandarin to eat frozen food and he actually took a piece of Brine shirmp last night. Only the 1 piece but it is a start, hopefully it isnt that the mandarin is starving but it doesnt look to have lost much weight.