Been trying to add more biological filtration to my 90 gal however a sump system is not financially an option for me at this time and I feel the need to tinker with my setup. Was thinking of placing a tray perhaps 10-12" wide 3-4" high and 3.5' long on top of the tank at a slightly descending angle. In this tray will be scrubbies pourous rocks or another biological media. Water will be pulled from the tank via a 170gph powerhead where it will then course through tray then out a spout at the end back into the tank. Just wondering if this could work and if it does would it be worth my time to make it. Also If I just used the powerhead to run a sump would that work or would it be too much head for the little pump?