Where and how many holes should I drill and what size? I want to go for something very quiet... I have been reading about euros, herbie, bean and now I'm confused which is best. I can only drill in the back, please help with some tips as I plan to drill tomorrow.
I've never heard of a "euros" drain??
The usual opitons are as follows;
Duroso / stockman (vented drain aka open channel)-
These require one hole, and can flow up to around 600gph max through a 1" bulkhead.
These will mix air and water and will never be silent or bubble free going into the sump.
This is what pretty much all stock off the shelf RR tanks will be set up with unless you start modding things.
Herbie (restricted siphon with dry emergency)-
Requires 2 holes and will flow well over 1000gph easy using 1" bulkheads.
This is a pure siphon so there is no noise and no bubbles into the sump if set up correctly.
The flow rate is determined by a gate valve restricting the siphon drain. This setting needs to be just right or it will either back up and hit the dry emergency drain, or start flushing.
Herbie drains do need occasional slight adjustments.
If the siphon drain backs up the dry emergency is capable of handling all the flow and more.
Bean drains (restricted siphon, dry emergency, AND open channel)-
Require 3 holes, and flow capabilities are essentially the same as a herbie.
This set up is a herbie and an open channel. The addition of the open channel pretty much eliminates the occasional adjusting needed on a herbie. The open channel also creates a second back up in case the siphon AND dry emergency back up somehow.
*note, reccent hands on exp shows that herbie and bean drains involving runs of plumbing near horizontal can be tricky to get dialed in and consistently restart without tuning issues.
Also note, when drilling holes it's usually reccomended that holes be spaced at least 1-1.5x the diamater of the hole- from any other hole, and from any edge of a glass pane. Holes drilled close together tend to like to play connect the dots (ie crack)