[COLOR=blue] We have a 60 gallon tank, and have been using this type of filter system with the double Bio Wheels, the Magnum Pro 350 System.

Well, it's done a great job keeping our fish healthy and water levels where they should be. We had trouble with the bio wheels suddenly stopping so they weren't spinning and we cleaned everything, rinsed the wheels, checked all we needed to according to the instruction booklet.

We have been rinsing the blue pre filter that fits around the charcoal canister container.. It's been a year now doing this, and we've noticed the pre filter was getting a bit worn, but no holes, just used.. The booklet says nothing about changing this filter or how often so we thought it was good to keep it rinsed monthly because of the good bacteria idea.

Since nothing seemed to help with the bio wheel interruptions, we went to our pet store (PetSmart) and looked at the pre filters for this system, and on the bag it recommends changing these MONTHLY!! We feel a bit stupid here. DUH we said!

We realize now the good bacteria is in and on the bio wheels instead, and hope Marineland instructs people who buy their filter system to change this filter often or at least every other month! Would save alot of worry on fish owners minds!

Anyone else have this system and run into this same problem? Did you figure it out sooner than we did?

We are writing to Marineland about this, to let them know it's important enough to add to their instruction manual, since everything else about the filter system is explained and directed..

Just sharing to help someone else here who are new fish owners like we are!
And feeling a bit dumb as we go! haha

Lynn hc220@aol.com

Of COURSE ML suggests replacing the filters monthly. They'd suggest changing them weekly if they thought people would believe it was necessary. They can last much longer than a month, depending on your fish load, when they are rinsed out as you have been doing. Since, as you noted, the prefilter is not the primary source of biofiltration, I just rinse mine well in tap water, and it's much easier to clean them well this way. Even with rinsing, though, the filter will eventually need replacing as the fibers break down or water doesn't flow through as it once did.

Of course replacing the filters monthly isn't going to do any harm, but it is only really necessary when the water flow is impaired (which probably isn't after 4 weeks of use).

Biowheels will also slow down quite a bit as they become colonized with beneficial bacteria. Some of mine move in short spurts only once every few seconds. Did yours stop entirely, or just stop/spin, stop/spin?