ok, So I have an eclipse 12 i got from one of my managers, and it has no filter. I was hoping ordering a filter from marineland would be easy, but its to expensive. So my new idea is to hack it to bits and put an aquaclear or a penguin on it.

any suggestions on how to cut up the lid without killing it?

Um... well, I dunno about the 12, but the hood on my 6 has a little notch in the back for "accessories." I would just make that bigger. Hmm... lemme go look at mine real quick...

Yeah... I think that would work. I'm not sure what you would cut it with, but it shouldn't be too hard.

Depending on what you're planning on putting in it, you could also use an internal filter.

I'm not familiar with those types of tanks. What is the lid made of? If it's hard plastic you could score the part you want off with a box cutter really well and then just snap off the part you want gone.

The Eclipse tanks in general, have the same footprint as many "common" tank sizes. The Eclipse 15 is the same as a 10 gallon tank. A regular hood for a 10 would fit on it.

Measure the 12 and see what you have in size.

Otherwise, you can slide the slide locks open and remove the back cover. HAve a you new HOB filter empty into the same well as the original filter emptied, going out past the biowheel. You can drop a sponge, or extra biomedia in the well, along with the regular cartridge. It should work just fine.