Bean animal plumbing question

[jsweir]

Have 4 holes in my overflow, two one inch and two 1.5 inch. Set up one 1" as the return and planning on using the other 3 for bean animal. Set the length of the full siphon 1" at 6" below the weir, and a 1.5" emergency at 1/2" below the weir. Now the question is how tall do I make the "durso" style bean secondary 1.5"? I can't seem to find anything so far.

 

[NinjaTiLL]

Just needs to be 1/4" above the other. You tune the full siphon so it handles 99% of the drain flow. The other 1% is handled by the secondary.

I have an Innovative Marine 75EXT and all 3 are 1" drains and the tank comes with the in-overflow fittings. They have the full siphon without any stand pipe... just the bulkhead at the bottom of the overflow (and I added a strainer). The secondary is about 1/4" below the tank weir and the emergency is just 1/4" above the secondary. Both secondary and emergency have a piece of un-glued PVC pipe coming out of the bulkhead to make those levels; no fancy durso fittings. It is very quiet with just a trickle going down the secondary.