overcrowded

Hello, I have an overstocked 10 gallon tank and I need suggestions on good filters because the current one is meant for 10-20 gallons but it isn't good enough. I plan on upgrading my tank to a bigger one soon but until then I need a good filter for my tank that isn't stupid expensive and I also...

*For starters i would like to say that there is no fighting in my tank, they all actually have a good amount of space im more concerned about the bioload in the 20 gallon, so give me tips, please. So, Basically to put it simply i fear that i have over populated my 20 gallon long tank. These are...