Surge tank and overflow height?

[moosehead]

I am setting up a 90gal tank (48 long x 24 wide x 18 high). The tank will have an overflow along the full width of one end (full tank length will actually be 54"). If I want to add a 10 gal surge device that drains in under 15 seconds how much extra height will I need between the top of the overflow and the top of the tank?

I know that 10 gallons is 2" height in this tank but I also know that while the surge is emptying the overflow will be draining the excess. Any surge gurus out there to provide me with some guidance or the benefit of your experience?

Thanks!

Jeff

 

[Anonymous]

That's a pretty fast emptying rate. I take it you're using 2" PVC for the surge outlet?

It's really hard to calculate this stuff out on paper. I always just set it up and see what happens. If you're really worried about a flood you can pump water from the main aquarium to the surge device instead of from the sump.

 

[moosehead]

Thanks for the thoughts Matt. I will be getting the tank built shortly and was just trying to determine if I should lower the overflow "just in case" I add a Carlson surge in a year or so. That rate is based on 2" or maybe even 2.5" pipe which is what I thought would be useful as a surge. Surging once per minute provides average additional flow of 600 GPH.

Cheers

Jeff

 

[moosehead]

oops - double post

 

[Anonymous]

If it does go too fast, you can always add a reducer bushing at the end of the pipe and slow dow the flow. I had to do this on a 30 gallon tank I had a while back. Two surge devices + two 1" outlets + one 1" overflow=a nearly flooded floor

 

[Ogre]

Moosehead, that's a pretty decent size surge for that tank. I used to run a 4 gallon surge on my 52 and it stured everything up in the tank very very well. There was no detritus on any of the acro's and the rose loved it. The surge only went off every few minutes and it lasted for a good 15 seconds from beginning to end. Surging once a minute will surely give you a lot of additional flow into the tank. Might be a bit too much. You'll also need one hell of a pump to fill that up. How do you plan on triggering the surge? syphon start?

 

[moosehead]

I was planning a syphon. With 2" pipe it should drain in about 15 seconds. I would expect to fill it from my sump with a dedicated pump delivering about 600GPH to fill the tank once per minute. I will be starting with about 1100GPH curculation from my sump on 100gal of tank volume and thought a good way to add more flow would be another 600GPH through a surge. Do you think it will be too much?

 

[Ogre]

Well, when my system was running, the surge was going every 6 or 7 min. I think that if you try to fill it too much, it'll take to long to have the siphon start and you could end up just pumping water to your floor. A 10 gallon surge is good sized surge for that tank. I'm not sure if you would want to have it surge every minute. It takes a few minutes for bubbles to clear from the tank. I'd try something a bit slower than that. Maybe every once every 5 or 10 minutes at first. A surge is one of the best things I could have ever done for my tank. Everything in the tank loved it. Even the clams didn't mind it. But some of the bubbles did get stuck on the underside of some of my acro's. Be careful.