Get rid of the filter. I would get instead a fluidized bed filter such is sold for use of phosban and a small pump to go with it. It can be used more effectively with carbon and phosphate removers than a typical HOB filter or canister filter, or a bag of media in a sump. It will also accept usage of any other filter media you might need to use. Just use it when it is needed, other wise it can sit out of the way. It would be a very good idea to try to get a Skimmer though. Your nitrates will build up much slower with a skimmer, and your future problems with algae will be lessened in number and severity both. A good skimmer is usually the highest equipment expense except lights taht most reefers experience. No good skimmer is cheap. Shoot, even bad ones are not cheap.