Coming from the land of Marineland HOB filters, I was quite impressed by the XP3’s power.   But, I was quickly disappointed with how fast it became clogged to the point of no longer running.  As I learned more about what the filter really needed to do, I changed my strategy of filter media in the XP3.  I had been using two coarse foam pads in the lowest bin, two medium pads in the middle bin, the charcoal bag in the bottom of the top bin, and the micro filter in the top of the top bin.  The whole thing would become a solid mass of black tar like stuff.

So, My new strategy was to use mostly bio media.  It looks like this:

• Top 1: micro filter pad
• Top 2: bio media
• Middle 1: bio media
• Middle 2: bio media
• Bottom 1: medium foam pad
• Bottom 2: coarse foam pad

I found that the filter would run for about 6 months before needing to be cleaned.  The downside to letting the filter go that long is that you may miss rescuing fry that got sucked in.  I once found a nearly adult size swordtail dead in the bottom of my filter.  What a horrible existence it must have had.  I now check my filter for fry with a flashlight every other week.

Back on track…

The next advantage I found with the XP series was when I bought a new tank.  On my existing 55G tank, I had an XP3 and a Marineland 350 HOB.  I connected the new XP’s hoses to my new 55G tank and took unplugged and disconnected the XP3 from the existing 55G.  The new XP3 was connected to the existing tank.  Viola - my new 55G tank was instantly cycled, and my existing 55G did not show any noticeable signs of a mini cycle.

So, I now have an XP series filter on each tank.  One of the tanks has 3.  If I ever have a filter break, I have a ready spare that is already cycled.  The interchangeable quick disconnects make moving them from one tank to another very easy.

 I believe just about each brand of canister filter has that ability.  I would highly recommend sticking with a common model of filter.  It will let you buy some spare parts that can be used on any of your filters.

My background is in industrial engineering and computer science, but I am now focused on technology risk management, disaster recovery and that sort of thing.  That background has made me look at and question many things that are commonly accepted, dreaming up experiments that I have yet to undertake.

 First on my list is to determine where the nitrogen oxidizing bacteria actually reside in an aquarium.  It’s commonly accepted that transferring filter media from an established tank to a new tank will either immediately cycle or dramatically shorten the time to cycle a new tank.  I have no less than 6 real world experiences where this did not happen.  My experience has been:

• Move filter media from a cycled filter (with appropriate due care) to a new filter.  Result: new tank is NOT cycled and must proceed with the cycle per normal.
• Move the whole filter from a cycled tank to a new tank.  Result: new tank cycled immediately.

So, in my experience, the media does not appear to be where a preponderance of the bacteria are living.  I have been theorizing that the bacteria are primarily living on surfaces that have some kind of turbulent flow over them, such as discharges, pump impellers, etc.  If I am correct, some amount of bacteria probably live at the very top of the filter media of a standard HOB filter, where water is somewhat turbulent.

I have been thinking of a some valid experiments to help determine where the bacteria live in different conditions.  If you have any input on that, please post a comment.  I will conduct the test once I have a good plan in place.