i want to make a little refugium on my 20 gallon tank i was wondering if i could take a little hang on the back filter, gut it, and fill it with macro algae like chato ( however its spelled ) and them put a little light over it, the mud is not required correct, is is just more work and just adds a little to the biological filtration considering bacteria will make a home in it and consume dissolved organic waste in the water stream right??? the plants also do this though as long as photosynthesis is going on right????