help...durso or herbie

[ScubaSteve]

Personally, I'd say if you can drill one more hole to with the beananimal design (basically a mash up of a durso and a herbie). Just built one myself using 1" lines and it handles retarded amounts of flow. I tried measuring the main siphon at wide open and it was over 1500 gph (in theory it could do 2000 gph at 3 ft of head. Use the Bernoulli equation or if you're lazy you can use this calculator). I have to turn it way down so that it stops draining my overflow box! I have the diamond hole saw for 1" bulkheads if you want to borrow it.

If this is not an option, I say herbie as it's basically the beananimal design minus the emergency overflow (which does an amazing job and I am happy to have). If the system is tuned so that the full siphon handles most or all of the flow, and you aren't introducing air anywhere into the siphon, it should be pretty quiet. Stick the pipe just below the water line of your sump and you're set. The water surface in my sump is almost like glass once the bubbles are out of the system.

I agree that the teeth on your overflow will be a limiting factor. I went with a toothless overflow for this reason (though it remains to be seen how I feel about that decision... Love it so far!). What is the length of your overflow and what percentage of that is actually opening?