I want to get a tank for a motoro ray this summer, I was thinking of getting an Emporer 400, cause I am used to power filters, but I wanted to ask what is the best filter overall for a ray, I am asking for spacific brands and some links would be nice. Also money is an issue, I am just barely finding money for the tank and the fish. around $50 is all I hope to spend. Some advise in filter media would be very helpfull too! Your help is appreciated!