Herbie overflow - what size?
 

Hi. I am planning an upgrade :biggrin: and need some help with the plumbing before I order the tank. The new aquarium will be 30x30x18" (about 60 gallons) with a 20 gallon sump. Return pump is a Tunze silence - with head and friction loss I should be getting about 350 g/hr with 3/4" pipe but I will probably dial it back to less than 300 g/hr as it is adjustable.

I am planning a Herbie overflow and would like some advice on the size the overflows should be. I have done a lot of reading but there are so many opinions on actual flow rates that I need help! I have read anywhere from 165 to 660 g/hr for gravity feed for 3/4"!!!! Is 3/4 appropriate for the flow rates I want or is 1" better for my setup?

I really appreciate any advice I can get. Thanks in advance!!!!

I would go as big as you can on the tank. I would go at least 1" if you can if you can go bigger. If somethig gets stuck (stupid hermit etc) or plugs it you dont want to have "just enough" to handel the volume from your pump.

check out the beanimal design. I like it better.

Thanks for the suggestion. I have looked at the beananimal design. It looks good but I do not have the room to have plumbing external to the aquarium. A 30x30 is the max room I have for a new aquarium and the beananimal design would take up too much real estate inside, that is why I had decided on the herbie.

Both the Herbie and the Beananimal work best with a coast to coast overflow. You want just the surface tank water to enter the overflow and you want it to "hug" the sides of the overflow as it goes in. Otherwise you have a very large volume of water being pulled through a (relatively) small overflow box. This leads to a lot of problems with fishes or other animals getting sucked over the weir, or it results in a loss of efficiency as the overflow no longer pulls just the surface water. Therefore, a properly set up overflow for a Herbie will be large enough for a Beananimal as well.

I would go 1" as a minimum for your open channel and 3/4" for your siphon. If you are going with 600 gph, I'd do 1" and 1" (and 1" for the Emergency if doing BAA).

The bigger, the better (within reason). Remember, a Herbie is designed to be adjustable downwards with the gate valve. It's much easier to fix if you've gone too big, than if you've gone too small.

check out the calculator on Bean Animals site (here, towards the bottom) it basically show how much a siphon can flow so can be used to size a Herbie.

Thanks everyone! I didn't realize the Herbie required a coast to coast overflow. I guess I have to go back and do more research.

You don't need a CtoC for a Herbie (maybe for the Bean).

thanks Mark, I really didn't want a CtoC overflow. Also, thanks for the link to the calculator it will help me with the pipe sizing.