Kids have a 5 gallon tank from Topfin, which we filled with freshwater and have tropical freshwater fish in it.

We have filter cartridges and all that, and have used water conditioners and the bacteria supplement the way the instructions say to put it in, but the water gets pretty gross, cloudy, and smelly within 5 days every time. The filter appears to be working as it is pumping out water, and the filter cartridges are gross every time I replace them (at least weekly), so they are obviously catching quite a bit of stuff.

The question I have is if there is something obviously wrong. I understood that if you used a filter, and changed it weekly that you should only have to change the entire tank about once a month. As it is, we are having to change the entire tank almost weekly, and each time I spend a fair amount of time rinsing out the gravel with hot water (not with soap or anything).

The tank has 3 tropical freshwater fish and 1 sucker fish, all about an inch or less.

Meanwhile, we also have a little fishbowl with a beta, and there is no filter in the beta bowl. The beta bowl is pretty clean and only needs to be changed every couple of weeks or so.

Seems like it might be a tank or filter issue, but I don't know enough about it really. Tempted to just flush them all down the drain and tell the kids Santa told us he made a big mistake and had to take them all back to some other family in Indonesia.