since u don't have any corals in there . I would start by taking out the rock a small amount at a time . place the rock in. a. hydrogen /RO water mix this will kill the algae and let the rock sit in the bucket for a day. rinse the rock off and put it back in the tank. do this with the rest of the rock. don't worry about ur pods they will survive and u have a sump. on the sump u want to add. some rock or get a glass like a big 16 oz glass fill the glass with sand and cap it with some lie rock pebbles. this will be a sand filter and will help reduce your nitrates.