During backwash I noticed the flow had decreased dramatically. Turns out the 2" elbowed pipe on my retro bottom drain was clogged with leaves.

The good news is that forced me to install the 3" aqua art retro bottom drain I bought months earlier. Since it's 3" with no elbow, I hope to avoid the leaf problem in the future.

I'll use the 2" in the shubunkin tank since it's not very deep and the BD will be easy to get to.