sump for a 210


New member
Im planning on making a 48x16x16 sump for a 210 gallon tank.

I havent tested how much water drains out into the sump on a power failure.

Do you think a sump like this with normally filled up to the 8 inch mark, would hold the extra drainage from a power outage?


New member
I have a 48x18x18 on my 210 gallon tank.I run my water level at the 9 inch mark and when i shut off all my pumps it only goes up about 2 more inches.So yes you will be fine.


Premium Member
The amount of drain down will depend on quite a few things. How much of a water level change do you have between operating and no pump on the tank? IE with a higher flow return pump you will have more drain down. How much water does your return line hold? Is it 3/4, 1, 1 1/4, 1 1/2, 2 inch, how long? You should be pretty safe as triggerfreak says, but without knowing how much your tank drains. The sump will be able to hold an extra 26.5 gallons of water, so assuming you have say 3 gallons in your plumbing that leaves 23.5 on the main tank, which is right at 3 inchs in the main tank. But what about your skimmer, will it drain down? Do you have a seperate fuge?



In Memoriam
I bought a 75 gallon AGA tank and used that for a sump (48 * 18 * 20) on my 210 AGA.

My tank drains about 15 gallons and the sump holds it OK. BTW, I'm also using a refugium in there so there's plenty of space.

So to answer your question. There's a calculator here (RC's main page) that will help you calculate the sump volume needed.

I took the liberty and did the calculation for you assuming you'll use a 1200 gph pump and the math comes out to this:

Using the following input parameters
Tank Length = 72 inches
Tank Width = 24 inches
Height of Water above Overflow = 2 inches
Flow through sump = 1200 gph

Sump volume is calculated as
Sump Volume need to handle tank overflow = 15 Gallons
Recommended Minimum Volume for sump = 27 Gallons

According to this you'll need around 15 gallons of free space for your overflow.

In a 48 x 18 sump that equals to a little over 4 inches of water.

Here's the math:

(48 x 18 x 4) / 231 = 14.96

Of course, everything changes with different parameters :)



New member
Thanks for the responses.

I used those great calculators like this:

The sump will normally have about 31 gallons in it I figured.
The overflow will be 15 gallons.
The 48x16x16 sump can hold a max of 53.2 gallons.
So 31 + 15 = 46 gallons when the power goes out, so I should be in the safe range.

Cant make any mistakes like that before I build the sump.

Thanks for the info again.