HEY MarkJ - I have had a 37 gal marine tank for 3 years and use the Rena filter. I had some ups and downs early on with algae and trying to keep an anenome but for the past 2 years it has been well balanced and seems to be under control. I clean the tank once every to 2 to 3 weeks. I change about 30% of the water and always clean the filter. I usually change the top micro filter and rinse the sponges under tap water, however, once I am done rinsing the sponges under tap water I immerse them in the discarded salt water before I put them back in the filter. One thing I don't do is rinse or clean the ceramic rings. I have two percula clowns, 1 yellow tang, 1 flame angel, 1 lawn mower blenny, three algae eating hermit crabs, 6 turbo snails and 1 hermit crab. Good luck with your tank, not saying I am doing it right but it works for me.
