Thanks Laura!
You may be able to use just one Eheim 2217 (I think it's now the 600 model) since you have smaller fish though that large Pleco does produce a lot of waste. Adding a 2nd one would give you good circulation and filtration capacity.
I only use the Eheim filters so definitely look at other brands as Jessica suggested.
Rufus, my one eyed Pleco, has been with me for about 10 years. I got him when I had a 40 gallon tank. He moved to a 60 gallon and now he is very happy in the 125 gallon. He was about 2 inches long when I got him. Yes, he does produce a lot of waste. I clean up after him all the time.
The Ehiem 2217 is the one I have been looking at. Thank you for sharing your insight with me. I appreciate it very much.