Have not changed a thing, and just cleaned my filter for the first time in probably 2 months or maybe a little more! Flow was still great but I did get a bucket full of crud after washing all of the sponges. Hardly anything comes out of the sponges being used as media. The poly-fill gets replaced every time I clean the filter. The other sponges did not even look that dirty but did release a TON of stuff in the bucket. Really happy with the filter setup. The Oscar is quite large now and the other fish growing too. I'd say a Fluval 407 is not a big filter by any stretch for a 75 gallon with this stocking.....I do a 70-80% water change every other week and nitrates never get above 20 ppm. They probably hover in the 5-15 range. Again, this is only changing water every other week. I may have to up this as the fish grow before I get a larger tank, but I am beyond pleased with the results!
