I have one 6" bar guard on a pond and two 4" bar guards on wetlands and also find them useful for keeping debris out of the pipes. I no longer worry about fish washing out. That is just something that happens and does not seem to have much effect on the fish populations in my three ponds. I built cages around the pipes on my two biggest ponds rather than using bar guards to increase the surface area because they get more flow-through during heavy rains and I wanted to reduce the chance of clogging..