Bait tank

[mrJB]

Tarpon Guy -
I have the "backflow preventer" that you have pictured and have been using it without problems for the past year. Mine is mounted below the pump, which draws water up from a scupper. My pump is 12 volt however, and, after the initial morning priming of the pump it goes all day, on and off (on a timer) while holding it's prime. One thing critical here is that there can not be any air leaks in the line or the pump will suck air instead of water. Threaded connections are not air-leak proof - use teflon tape.Maybe mine's working because of the 12v flow or ?? but that $3+ valve does work for me...
A few other things... a folding lid on the bait tank is not necessary if you have a rim on the top of the tank, i.e., the bait will swim up the side to get out but not jump directly out. In the future, you may reconsider the outflow rather than have scales, etc. all over. If you do, you will need 1 1/2" outlet for full 12 v flow, 1 1/4' for 6 v. or 12 v. on a timer...
The very simplist solution is a bilge pump on a 3' hose, (a "dragger") - no priming, cheaper to buy. The downside is that there is a noticeable bit of drag...
Hope this helps
John