"Head loss" in ZooMed and Tom Rapids filters?
I'm trying to decide on a canister filter for a 6 gallon tank- I know, join the club. I am of course looking at the Tom Rapids and Zoomed filters, and also the Eheim 2213 but I'm worried about excessive flow for a shrimp-only tank.
I plan to place the filter in the stand about 24" below the tank because I do not like to see equipment, but I keep reading posts on Zoomed and Rapids filters that the pumps are "not powerful enough to overcome the head loss" to be placed below the tank.
I don't understand this. I always thought in a closed loop system like a canister filter there essentially is no head loss since the pressure needed to pump the water up the return is countered by the pressure flowing down the intake.
I used to have a small DIY canister that used a crappy fountain pump and I was able to get OK flow with the filter located 3ft below the tank.
Am I missing something?