if your sump has LR
and, i'm assuming, some sand, then I would get rid of the bio-balls. The bio-balls are good for turining nitrites into nitrates, but they lack the sub-surface bacteria to turn nitrates into escape gasses that leave the tank. your LR
will do that. That combined witht he sponges could be the cause of your light nitrate rise. Do you use the pods
for feed tank fish? if you don't I wouldn't worry about what you'll lose in the sponge. The LR
will have the majority of the pods
. What I would do when cleaning is take the sponges and give them a liberal shake-n-swish in the sump water. Hopefully the majority of critters will scurry out. then you can clean your sponges with minimal critter loss.