Currently I am having problems getting my nitrates set low and have had a spike in hairline algea. Phosphates, calcium, ph and nitrites are all very low. I have a 40 gallon breeder and running a canister filter. I don't have room for a sump or refugium, but have heard about the hang on the back refugiums. My question was how efficent are the hang on back refugiums in lowering nitrates and balancing out water?! Any recommendations?