What models are the two filters? Is the marineland an emperor or a penguin? The reason I ask if you change the two filters at the same time is because when you change that cartridge you are throwing good bacteria in trash. Tho it is is necessary to replace these cartridges you do not want to do them at the same time. I clean out my two filters one at a time this way you won't stress the bio load as bad and it gives each filter time to catch up again instead of both fighting each other at the same time.
I don't know much about the aqueon but the marine land (if its a bio wheel) has room in front of the cartridge I would recommend putting one or even two fluval clearmax in there. The clear max traps phosphate nitrite and nitrates. I had nitrates at just over 20ppm I put the clear max in and did a 20% water change with a gravel vac the next day I was reading zero.
I don't know much about the aqueon but the marine land (if its a bio wheel) has room in front of the cartridge I would recommend putting one or even two fluval clearmax in there. The clear max traps phosphate nitrite and nitrates. I had nitrates at just over 20ppm I put the clear max in and did a 20% water change with a gravel vac the next day I was reading zero.
