Got me some new fish!!

I know they get big, but they are by far the best fish to clean algae, nemotodes, and other stuff that grows in a tank. Personally, if they were not such good cleaners, I would not have them at all; in fact, I would rename them spider fish because they always leave webs of poo aroud the tank which is very annoying. I know I'll have to ditch the guy before long. Is there a cleanng crew I could assemble in the 20 gallon tank that would be alright??? Some cories maybe??? I would just like to clean the algae and such and I hate sticking my hand in the water not knowing how it affects the water.

Quick update: I have noticed that one of my panda cories has been racing up and down and across the front glass of the tank. Is this normal??? And another thing, once I do get rid of the pleco and the spotted rafael (bad purchase), would it be possible to get some more cories and maybe another schooling fish??? Thanks!
 
AquariaCentral.com