Planted Tank Guru
Join Date: Jun 2004
Location: Baton Rouge, LA
I use a Magnum 350 canister with an Aquaclear 70 HOB on my 46g high-tech bowfront. I also currently run my CO2 into it.
It's short on filter media capacity compared to other canisters. But it's very versatile. I can use carbon, bioballs, micron or diatom filtration. I would probably not buy another if I were to get a second canister, but I'm glad to have this one and will always find a use for it.
I bought the Pro version for the quick disconnects which are incredibly handy. If you don't have those, I suggest looking into adding them. A quick tip - after disconnecting the canister from the aquarium for maintenance, open one of the disconnect valves. Otherwise, it will be hard to remove or replace the top because it's sealed and under pressure/vacuum. Press down hard on the top when latching or unlatching the metal clips, this reduces stress on them; they can be bent if you're rough.
The micron filters do a good job of general water polishing. They last about a week for me before the flow rate decreases too much. The tip about having two micron filters is good, as it takes a little while to bleach them clean. After about six months of constant use, I noticed the flow through the micron filters decreasing even after being freshly cleaned, and they were discolored. Spraying them alternately with vinegar then H2O2, a few minutes apart, restored them to like new. I figure it was a combination of mineral and organic buildup that the bleach was unable to remove.
For cloudy water, charging a micron filter with diatoms does a fast and thorough job of cleaning it up.
Use only biomedia without small particles. Some cheap carbon has such particles that can slip through the mesh and tear up the impeller.
I've been using the Magnum for about a year now. I did purchase some common spare parts like gaskets after reading some negative reviews, so that I would have no downtime in case of a failure; but by using the above tips, I haven't needed any of them. Just treat it properly and it should last you a long time.