I can say for a fact that this type of feeder works well. My father has a house on Lake St. John in Louisana with a good size pier, about 80ft out and with a covered boat lift and sitting area (the deck section and lift are 20x30ft).

He decided to feed the catfish so he could catch a lot of fish. So, he cut a 6in dia PVC pipe long (approx 12ft) enough to stick straight down into the mud under the covered section of pier. Before placing under pier, He used a 1/4in bit and drilled large numbers of holes in the pipe, looked like swiss cheese. These holes are all below the water line. He cut a hole in a pier plank and pushed the pipe vertically into the mud until the top of the pipe was flush with top of plank.

We use sinking catfish food. The catfish will suck it out through the holes. It works really well. Every catfish is so full of feed the look like they are going to pop. The fish will congreate like no tomorrow under your pier. We also keep lots of xmas trees and cypress limbs under the pier. Also, we dump the shiners out when the week-end is over. Grew some nice ones on the feed. The bass like them a lot.

One May (water still clear) some years back I got my dive mask and got in under the pier, grabbed hold of one of the 4x4 posts and dropped to the bottom and held my breath for as long as I could. It was a fish hotel, lots of suspending bass, crappie, big bream.

People figured out we had a good fishing pier so we cut a 3ftx3ft hole into the floor next to the feeder. Around the exterior edge of the deck, we hammered up a heavy rubber mat from deck down to a couple of feet below water line. The dark under the pier really attracted the crappie. The bigger bass often hang up, but great for crappie, bream and cats.