In the process of setting up my new to me 120P. I plan on running an eheim pro 4 350 and a fluval 306 on opposite ends of the tank. Did not plan on a heater for the setup but was going to have an quanvee inline CO2 atomizer most likely on the fluval side. I was also going to have intake with a skimmer on one of the sides as well. Haven't sorted out what sort of pipes I'll end up with, still rockin the eheim "lily" black / green lily pipes right now.
On the fluval side, I might be intermittently swapping it with the 406 that's running on my other tank as I service it. I'm not sure if that's a wise choice or not. Basically I'd clean the filter on my 210 and then put the cleaned filter onto the 120P while moving the filter from the 120P to my 210. It kind of forces me to get the 210 filter cleaned in a more regular schedule since I service that tank quarterly. Don't worry the 210 doesn't have just one filter.
Initially I wasn't a big fan of high flow filtration but I got used to it after having a Filstar L on my 40g and then an FX4 on my 47 gallon column tank. Then my UNS90L has a 2215 with 2217 impeller plus an Eheim 350 skimmer on the opposite end. Just wanted to see if that flow would be adequate with the pro 4 350 / 306 combo for the 120P or if a step up down the road should be considered.
Here's when I was messing around with some stuff I had laying around.
I was using an old magnum biowheel setup with the 306...