I feed frozen krill, talapia, live blackworms 2-3 times a week. but i feed hikari products for staple diet since mine wont touch NLS. I think its very important to get them eating whatever staple food first before introducing treats
and as for filtration goes, im not an expert and dont know what an Emporer 400 is lol sorry. I use AC 110's and on my 4' tanks i use 2 filters and 3 on my 6' tanks with airstones and sponge filters plus i clean my filters once or twice a month too