Sump Tank Size

[Michael Quinones]

I'm seeting up a sump tank for a 700 gal. tank.   Is there a formula / rule of thumb for Sump Tank size?   I planned to put in a 2'X2'X7' about 209 gal. Realizing I don't know what I'm doing I thought I should ask the question what size should the Sump Tank be in relation to main tank?

[Jon Nose]

I use a 2 x the amount needed for Gravel  beds filling ... leaves room for evaporation as well as in case all beds are filling up all at once ... if not enough water .. pump goes dry .. beds don't drain..............

[TCLynx]

Here is a blog about it

http://www.aquaponiclynx.com/how-to-size-your-sump-tank

But as Jon says, bigger is often better when it comes to water volume in sump tanks since not big enough means issues with pumps and more water in a system adds to stability.

[Michael & Kristine Stoddard]

So if the side of a standard 275 gallon IBC is 46x47" and if the media is 12" then you have 25944 cubic inches, divided by 2 equals 12972 which is 56.155844 gallons. Round down to 56 for simplicity and you'll need 56 gallons of sump for every IBC flooding to 12"?

[George]

Media takes up 60% or so of the volume of flooded media, while water fills the other 40%, if that helps.  Generally, if you have 12 inches of media, only 10 inches of that will be flooded.  

My tank is in the ground and I use an indexing valve to flood only one bed at a time (no siphons), so this isn't something I've given much thought to.

good luck

[Michael & Kristine Stoddard]

Right, I'd forgotten about that. I was using the same numbers I'd used to calculate the amount of media I was needing.

Not a big difference, but it might make a difference if you're cutting it close.

So, using the same numbers with 10" instead of 12" amounts to approximately 48 gallons of sump for every IBC flooding to 10". Sound about right?

...unless you use the top/bottom of the IBC which are usually 46x40. 

[George]

Should be plenty