180RR & 40B Sump Return Chamber Size

[HardCory]

I'm about to build my 40B refugium sump for my 180RR display. I'd like to know how long you made your return chamber to accommodate the water that continues to enter the sump when you kill the pumps?
I already know how big my skimmer section will be (roughly), and whatever is left after the return section will be the refugium section.
So, to reiterate: in a typical 40 breeder sump, how far from the outside wall did you build your last baffle to make sure there's enough room for water during, let's say, a power outage?

 

[Radman73]

I'm about to build my 40B refugium sump for my 180RR display. I'd like to know how long you made your return chamber to accommodate the water that continues to enter the sump when you kill the pumps?
I already know how big my skimmer section will be (roughly), and whatever is left after the return section will be the refugium section.
So, to reiterate: in a typical 40 breeder sump, how far from the outside wall did you build your last baffle to make sure there's enough room for water during, let's say, a power outage?

It's not so much the return chamber as it is the entire sump. In general, your sump will fill up to above may baffles. For instance, I use a 20H as a sump for my 60 cube and in a power loss the water level gets about 2 inches from the top. I expect about the same for the 40B I build for my 220. Much will be based off of the "working" volume of the sump. If, during normal operations, your sump contains 25gal then you theoretically have 15gal capacity for when power is lost. If you are running a high volume in the sump when everything is running, you may not have the capacity in the event of a power loss.

You can do an estimate of how much volume you'll gain during power loss. Or, you can test and find out

 

[HardCory]

It's not so much the return chamber as it is the entire sump. In general, your sump will fill up to above may baffles. For instance, I use a 20H as a sump for my 60 cube and in a power loss the water level gets about 2 inches from the top. I expect about the same for the 40B I build for my 220. Much will be based off of the "working" volume of the sump. If, during normal operations, your sump contains 25gal then you theoretically have 15gal capacity for when power is lost. If you are running a high volume in the sump when everything is running, you may not have the capacity in the event of a power loss.

You can do an estimate of how much volume you'll gain during power loss. Or, you can test and find out

Unfortunately, I really don't have the option to run tests until I'm able to set it up in it's final location and by then, I really don't have a choice on what happens haha!
I was just trying to get rough idea on what people were doing and where the final water level would be.

 

[Radman73]

I understand. I'm in the same boat as I have some concern that a 40B can handle the additional volume. Then again, my runs are extremely short and I use a ghost overflow so water draining from it should be no more than a couple of gallons. There's not a hard and fast way of determining what volume you'll increase by. I'm actually wishing I had just used a larger tank for the sump but I'm confident that mine will hold any overflow. My plan is to test it and if it looks like it will overflow, turn the return back on or start cleaning lol!

 

[lion king]

Most of the manufactured sumps rated for as high as a 300g tank only used about a 30g total volume sump. So it's all about your baffle height and the available volume left. As an example the sump for my 210g has a 30 gallon total volume and the water level is 9", there's plenty of room. I would imagine you could have a water level as high as 11" in a 40b with ease.

 

[danferd2002]

Do the math. Take the lowest point in your display tank that the water will drain. Most likely your returns. Calculate how much water 72 x 24 x that lowest point. Use the calculator on the main page for tank volume with those numbers. Once you have a gallon number take your sump dimension length and width and keep changing the height until you get the same gallon number. Give yourself an extra inch or two and this is how much extra room you will need.