I like clown plecos because they stay small, but the two I have in my 33L gal are eating my plants a bit. I've got some chain swords that they attack at night, giving them a lace-leaf appearance, and lately I've seen evidence of them going after my Crypt. spiralis. I've tried dropping algae wafers after the lights go off, but in my last few water changes I've been seeing broken down wafers near where I drop them, so I don't think they've been eating them.
Aside from that, I've been using otos and amano shrimp.