The tank is a standard 10 gal. For lighting I have 4 20in T5's for a total of 40w. I do weekly to bi-weekly 1 gal water changes which is probably the primary means of filtration. I also have a cpr hang on refugium that holds about 3 gal. That's about it. I do feed frozen rotifers for the gorgonians and dose phyto every couple days or so, so the I think the water changes are needed to keep up with my dosings.