Byron, I agree that the best way to control algae is to keep your chemistry right by regular weekly water changes and maintenance. However, even though I am rigourous with my maintenance you can still get green algae on the glass. My tank is a 180L Juwel Vison 180, and I had a common plec live in it happily for 28 years eventually getting to a length of 18 inches, so you can keep large fish in smaller tanks. Whilst he was alive I did not have a problem with algae but once he died my glass started getting covered with green algae. I then got a couple of Calico Bristlenosed Plecs and the algae problem disappeared.