I;m in the process of making a hang on refugium so that I can put it behind my 2.5g tank, but I am concerned about the circulation after I put the refugium in. Right now I have a hang on back filter from a 30 gallon tank for circulation (I didn;t want a powerhead in there because it is so big compared to the tank) and it seems to give me good circulation. I just wanted to know how strong(water flow) will the return pipe be coming out of the HOB refugium? Will this be enough circulation for my 2.5? I would like to have a strong current in there. Will the water flow just depend on the powerhead in the refugium?