I have a ugf and a peguin mini filter. sonce my lfs only has a canester filter for up to 45 gallons, is this to much and i should look for 1 smaller, or is it ok?
You can never have too much filtration. The only thing that may prevent you from having a lot is if you have fish like bettas which prefer slower undisturbed water (lots of filtration would disrupt this)
Whereas if you have fish that prefer current, you can filter great amounts with no worry (I have two aquaclear 500's on my 75g cichlid tank, meaning the tanks water volume is filtered 13 times an hour, or once every 4and a half minuets)
I assume your extra filtration is for your 20g long? if that is the case, it may come in handy in the future, as you will most likely need to buy a bigger tank for the pictus and clown loach, as both will most likely reach an adult size of "8-10 in an aquarium.