How much head do you need for drains?

[WVNed]

I am going to do a through the wall type installation in a basement. I would like to get my sump up off the floor as much as possible to help my back. No more fighting wires, plumbing and equipment inside a stand appeals to me greatly.
I am planning a 200-300 gallon tank. Either an 8 foot long or a wide 6 foot peninsula. I want a tank I can walk almost all the way around with plumbing and wiring in a utility duct between the stand and fish room.

When looking at my external overflow now it is flowing around 500gph internally with about 1 inch of head between the front and back box.

I am thinking that about 10-12 inches in difference between the DTs on one side of the wall and Sumps and other tanks on the other in the fish room will be enough to do whatever I want in the future.

Is that going to work or am I overlooking something?

 

[ca1ore]

It will depend on the size of the weir and drains, and how much more flow you plan for the new tank.

 

[theMeat]

If doing bean animal or herbie...
To get a full siphon to work, with enough vertical drop, and room for control valve, would think you need a couple of feet at least.

 

[WVNed]

A 16" Synergy shadow is rated for 2500gph and has 3 x 1.5 inch drains.
This calculator shows ~ 3000gph for a 1.5 inch drain 4 feet long with 12 inch drop.
http://www.calctool.org/CALC/eng/civil/hazen-williams_g

It seems like it would be OK unless I am overlooking something.

You never know what you don't know.

 

[ca1ore]

Think about it this way ..... you need enough linear inches of weir to allow desired flow without excessive water level rise in the tank (my own rule is 12” of toothed weir per 500 GPH); you need adequate bulkheads through the back of the tank to the external box to ensure they’re not a bottleneck (my own rule here is 750 GPH per 2” bulkhead); then you need adequate drain capacity out of the external box to the sump. This is the trickiest as it’s a function of drain size, amount of drop and head pressure built up over the drain mouth. Also keep in mind the secondary, and design so that it can handle the flow if primary is shot.

 

[theMeat]

Have been running 1100-1200 gph on my 16” reef synergy for 4 years without an issue.
Reefready tanks have much less weir to gph recommendation than what you recommend

 

[ca1ore]

Have been running 1100-1200 gph on my 16” reef synergy for 4 years without an issue.
Reefready tanks have much less weir to gph recommendation than what you recommend

True, though I’d hardly hold a mass market reef ready tank up as the gold standard - would you? 12” of weir per 500 gallons is my own rule, I believe I made that clear. It’s not solely a capacity issue, but also a surface skimming optimization issue. On my current 450, I run 1,600 GPH through a 36” weir - it also runs without issue :).

 

[theMeat]

True, though I’d hardly hold a mass market reef ready tank up as the gold standard - would you? 12” of weir per 500 gallons is my own rule, I believe I made that clear. It’s not solely a capacity issue, but also a surface skimming optimization issue. On my current 450, I run 1,600 GPH through a 36” weir - it also runs without issue :).

Yup
On my 16” weir 220 I have a dc pump which is a lil over mid output setting. Whether I turn the pump all the way up or all the way down, the tank water level stays the same, or at least the change is so minor I don’t see a difference.
So me thinks you could safety up your gph recommendation

 

[lapin]

Good Rule.
On my 600 I run about 3000 gph thru my 42" weir. No teeth. Egg create. But then it has a little bit deeper cut out than most weirs.

 

[ca1ore]

Good Rule.
On my 600 I run about 3000 gph thru my 42" weir. No teeth. Egg create. But then it has a little bit deeper cut out than most weirs.

I think the ‘rules’ change with toothless weirs. When I still ran older style coast to coast skim boxes without teeth, I would routinely push 1,000 GPH per linear foot.

 

[mitch91175]

Usually takes 5-10 minutes before it drains, :eek: