Low-Filtration tank needs altering?

[dskidmore]

My current setup is a planted 75 gallon aquarium with only a sponge filter and a bubble wall for filtration/circulation. My ammonia, nitrites and nitrates are at 0, and I never had an ammonia spike when I had a massive bioload dumped on me by a friend. (Yes, my ammonia kit works, I do see spikes in my QT when I treat it with antibiotics.)

When I first set up, I had only the bubble wall. The sponge filter was added to take care of the fine dust stirred up when I move plants. (Didn't wash the sand before installation, paying for it now.)

I am currently having a green water problem, and considering fertilization and DIY CO2. (Yes, I have plans that should manage CO2 for a 75 gallon.) It would obviously be fruitless to run CO2 with my filtration/circulation based off of an air pump, so I need to change.

Any suggestions for low filtration that won't break my surface tension, and uses washable media? (I used to love my aquaclear sponge media on my smaller tank.)

I'm thinking a small Fluval Internal using a sponge, with a powerhead on the opposite end of the tank? The fluvial would add the cabability to run carbon if I had to, but I think it requires the special carbon pad instead of loose carbon I already own.

The other alternative would be a powerhead with a foam prefilter?

[BillD]

The internal would work, but they are difficult to hide. I would try a small powerhead with prefilter. I'm sure there are ways to use your own carbon in the internal.

[dskidmore]

I ended up getting the Fluval 2 Plus. It is designed to have it's pads back to back, so I could take out all the pads and put in a bag of carbon if I wanted to.

I'm somewhat disapointed, it seems to pump the water through a very small portion of the filter media, the majority of the filter media is backup so the filter doesn't get clogged if you don't clean it regularly.