Filtration boner ----- Help if you can, please!!

Sploke is right. As long as you don't have ammonia or nitrite readings that means the one pad has enought bacteria living on/in it to consume all of the waste the tank creates. You do want the second in the filter so that the water can't just divert around the side with the pad to the empty side when that pads starts to get clogged/slows down the water flow.

One thing - when your filter pads get all gunked up and you rinse them out- don't use tap water if you have a municipal water supply that contains clorine or chloramines- both will damage your bacteria. I pull my filter cartridges when I do water changes and rinse them out in the waste water I remove from the tank.

Also, I don't use carbon at all, you dont need it (unless you want to remove meds from the water, otherwise its really just a waste).

It all depends on what kind of fish you have there. Personally I like a lot of filtration so I have a one filter that is rated for a 30 gallon on a 10 gallon that has two small goldfish in it right now. It made a big difference from the one that came with the aquarium kit. It's at grandma's house and she tends to over feed the fish and goldfish are dirty to begin with. (I can't wait to get a bigger tank for them this summer). On my 5 gallon I replaced the filter that came with that as well to one that is rated for a 10 gallon.

In the aquarium kits they come with bare minimum filtration. You can always add another power filter at anytime. The one thing I recommend is that when you change the filter medium if you have two only change one at a time. I heard that carbon is only active for about 3 days. The rest of the time it has biological bacteria on that helps back down the nitrogen cycle. The pad on the outside filters out the free floating particles in the water and it also has beneficial bacteria on it. You can just raise out the pad under none chlorinated water, or the water that is you changed during a WC.

If you get another filter just leave the other filter running with the old cartridge and if you want to change it wait a week before you changed the old one.

i would say that running two seperate filters on any tank is the best idea, so if one filter konks out on you, you aren't left with a tank sitting with no filter.

sounds like i have the same filter as you, gregatwan, and what i do is add biomax inside the cartridges. (your cartridges should have a little black clip thingy on the top that you can take off to slide the media bag (the fuzzy white square part) off of the plastic frame. unclip the top of the cartridge, open up the media bag but don't take it off the black frame, and add in a small handfull or so of biomax (you don't want to stuff the filter cartridge full, this will decrease water flow through the filter). this will help greatly with your good bacteria levels. after you add in the biomax, slide the cartridge back in slot in the filter, making sure to keep the biomax distributed as evenly as possible from top to bottom of the cartridge.

hope this helps!

and as for cleaning the cartridges, yes, just swish them back and forth in a container of old tank water that you've taken out during a water change. i've had my tank set up with this filter and a canister filter for a couple of months now and i've not had to clean the cartridges yet, but that might be due to the canister filter doing most of the work in the tank.

oh, almost forgot to mention! the cartridges for these filters have carbon in them when you buy them. open up the clip and shake as much of the carbon out as you can. you don't need it unless you're trying to remove medications from your tank.

While many people think carbon is worthless, others, including some moderators on AC think it works very well to keep water crystal clear. I always use it on all 5 of my tanks.

What I do in both of my big tanks is run a canister filter. The better the filtration, the higher the biload can be. I have one 55 that has 14 Rainbows in it on two cansiter filters ( a magnum300 and a casade clone I picked up off of e-bay) that water has nothing more than been topped off for the past 9 months. for the plants it has vals, java moss and duckweed.
and I do have MTS snails and a pea puffer and 3 oto cats.

but I do have one 55 on a single canister filter ( using cascade 1000)

and I have 55 tank that has an over the side filter and it also has undergravel filters. I change the pads 1 a month.

as the canister filters I just have them stuffed with polyester fiber fill that
you get in the sewing center section of wally-world. carbon loses approximately 80% of its effectiveness after 3 days so I don't even bother with it.

but I would suggest if you don't want to tear your tank apart and put in undergravel, get a canister filter or the largest over the side filter you can find and suff it with polyfill. then chagne one or the other filter every other month.