Tank to Sump Ratios?

[Daniel@R2R Verified Admin]

Is there a rule or at least a suggestion on a tank:sump ratio? I know, I know...the bigger, the better, but if your tank is X gallons, then your sump should be at least Y gallons. I'm thinking maybe something like 5:1?

How do you plan how big of a sump to have?
What is the minimum size a sump could/should be? (I'm thinking there's no maximum because "bigger the better" has always been the rule for sumps.)

Photo by @Reefer_punk

 

[SPS2020]

My sump sizes have always been dictated by the size of the stand. I leave a bit of room for dosing, etc. and then get the largest sump I can fit.

 

[i cant think]

Is there a rule or at least a suggestion on a tank:sump ratio? I know, I know...the bigger, the better, but if your tank is X gallons, then your sump should be at least Y gallons. I'm thinking maybe something like 5:1?

How do you plan how big of a sump to have?
What is the minimum size a sump could/should be? (I'm thinking there's no maximum because "bigger the better" has always been the rule for sumps.)

Photo by @Reefer_punk

I honestly just go for a sump that’s 2.5’ smaller (length ways) than the main tank. As for the width (depth), I would try and go for a minimum of 1.5’.
This is for a medium-large size tank (3’+).

Anything less than 3’ and it just completely depends on how big the cabinet is.

 

[Mikey-D]

When I purchased mine. Bigger was the focale point. I also factored in equipment and I knew I wanted to run a fuge so that played a factor as well. After researching sumps in geneal and read that a good ratio was to have at least 1/4 to what your display was, I purchased a 34g knowing that I could at sustain a 120g or even a 150g in the future without sump shopping again.

 

[ReefGeezer]

I think sump size depends of flow rate and what you want to put in it. High flow > big sump, Big refugium > big sump, Big Skimmer and other internal equipment > Big Sump, All the above > Really Big Sump! I have a Trigger Systems Ruby 36 sump under my 90. It is like 36X16 and runs about 9" deep. That's about 20 gallons of water. The first bay is set up as a cryptic fuge. The second bay is almost empty with just a smallish skimmer in it. The return bay holds the return pump, a heater, and the ATO switch. Overall it is pretty empty. I'd say at roughly 5:1, in a low flow (500 GPH) system, it is oversized. BUT... I have room for other stuff if needed and everything is easy to access.

 

[rknapp]

I checked a site from a sump builder I trust (LifeReef), and it looks like the 5:1 ratio is a decent start, although I see the ratios change to more like 10:1 in sumps for larger systems (up to 300g).

I think there is only one hard and fast rule: your sump capacity must be able to hold all the water that will drain down into it when all your system pumps are off. And that amount will vary depending on the placement of your overflows and returns relative to the tank water line. It will also vary by how much plumbing and water-holding gear you might have that will drain back into the sump (skimmer, reactors, refugiums).

If you need to hold all that support gear inside the sump under the tank, you will probably minimize water drain but need more physical space for that gear, so that will become a consideration.

If you are like me, where you have a separate equipment room where most of that gear is external and above the sump, water drain may be more of a consideration, but gear space in the sump is not.

Also, what you do to manage the water drain back into the sump will figure into all this. The more you can control it with check valves, the less you need to account for back in the sump.

So I am not convinced there is a single magic tank to sump ratio that fits all cases, but once you fit all your gear, making sure you can handle the drain back from your setup is pretty key, or you will have one big mess from a planned or unplanned system power down.

 

[welsher7]

I always aim for 3:1 ration between display and sump. I think the lowest i would go is 4:1. Any smaller and you really have to watch the backflow from the tank when the power is out.

 

[firechild]

I think my philosophy on this has changed over the years. I used to advocate for the biggest sump possible (I had a tank about 10 years ago that had 2 sumps, 1 under the display and another 120cm sump in another room - for a 36x30" display). However, I think there are a few considerations. While yes, bigger is still better, it all comes down to 2 things -firstly as @rknapp mentioned, the sump must be able to handle the water that will overflow when the power is cut. Secondly, it needs to hold the things you want to put into it. A refugium, skimmer, mechanical filter (socks or roller) and a return pump (you could add heaters but they generally get squeezed in where they fit). These are the 4 things that most sumps will have. Most other pieces of equipment can be external. I started reefing in the days where everything powered was simply an AC unit which needed to be plugged in and the only external components were perhaps a calcium reactor (the CO2 cylinder was so big it stood beside the cabinet) and later a kalk container - mine was a 2L juice bottle with an airline gravity feed. These days most things are DC and have some sort of controller and we need extra space for dosing containers/dosers, ATO, reactors and all of our various controllers. I work backwards these days to work out how much space I need outside the sump, then work out how to fit my sump into the space I have left.

 

[Belgian Anthias]

Is there a rule or at least a suggestion on a tank:sump ratio? I know, I know...the bigger, the better, but if your tank is X gallons, then your sump should be at least Y gallons. I'm thinking maybe something like 5:1?

How do you plan how big of a sump to have?
What is the minimum size a sump could/should be? (I'm thinking there's no maximum because "bigger the better" has always been the rule for sumps.)

Photo by @Reefer_punk

Does one need a sump? A spare tank situated below the display tank? One has to pump the water up from a sump to the tank. needing a pressure pump. if a sump is used to put in a skimmer, UV , calcium reactor or and other hardware? The space needed? Maybe it is used as bio or and refuge.? The rule is as big as possible. Maybe it is used to increase the total water volume? Also then as big as possible. Some do have a water reserve X times the display tanks volume if the display tank is a heavy loaded mixed reef.

 

[Kodski]

Minimum sump size should be the following.

amount of water in the sump while the system is operating + the amount that drains into the sump while powered off adding a 5-10% safety factor

in the end, it’s actually quite easy to calculate using an aquarium volume calculator. I like BRS’ calculator because the height of the aquarium and filled height are two separate measurements. The basic idea is to calculate the actual volume of water in your sump by breaking each compartment into its own rectangle. Then to calculate how much water you can expect to drain into the sump, use the calculator to find the volume of your aquarium and just set the fill height or overall height to the height the water sits above your overflow when in operation. This should calculate the amount of water volume drained into the sump. Then finally add a safety factor and add it the the actual water volume in the sump and there you have the minimum water volume your sump should be.

example, a 75 gallon tank. 48”x18”x21”

calculated sump volume is 10 gallons of water. (Made up a number each sump is different)

The water height is 2 inches above the bottom of the overflow weir. (Again, made up number)

so that means that the sump need to hold at a minimum of 17.48 gallons of water otherwise I’m the event of a power outage, your sump will overflow. So add some safety, I’d say a minimum of a 20 gallon tank is required.

 

[Rcpilot]

I go by the old school rule of thumb. Sump volume is 1/3 the tank volume. It's been working for me since 1986. I know people do it different today. I like my way. It works.

 

[jmichaelh7]

3:1

 

[GarrettT]

Some people want a big house little yard, while others want a big yard and little house. Just depends on what you want to keep in your sump. Occupying more volume can be useful if you need it, but having a large sump that lacks any utility doesn’t make much sense. It really comes down to whether or not you want a refugium imo.

 

[mfinn]

Is there a rule or at least a suggestion on a tank:sump ratio? I know, I know...the bigger, the better, but if your tank is X gallons, then your sump should be at least Y gallons. I'm thinking maybe something like 5:1?

How do you plan how big of a sump to have?
What is the minimum size a sump could/should be? (I'm thinking there's no maximum because "bigger the better" has always been the rule for sumps.)

Photo by @Reefer_punk

I don't think there has to be a rule or even a ratio.
The size has to be big enough to put the equipment in that you want.
I personally think that if you have to constantly tinker with it, it may be too small.
Most of the time the stand limits the size you can go with.
I've always built my own stands and while planning the stand I plan out the sump.
I've built a couple sumps myself, but have found if I have a custom sump made by a professional, I'm happier.

 

[TehBrainz]

I go by the old school rule of thumb. Sump volume is 1/3 the tank volume. It's been working for me since 1986. I know people do it different today. I like my way. It works.

I assume this is referring to the amount of water volume in the sump as opposed to physical size of the sump? A lot of good comments on insuring potential total volume can handle power outage scenarios.

 

[d2mini]

The ratio doesn't matter. ANY extra water volume is a positive. Fit whatever size sump you can, comfortably, with enough room for your gear, both inside and outside the sump. And big enough to handle the overflow when the pump turns off.

 

[glennf]

A small footprint as possible to fit all equipment, necessary stuff and prevent overflowing during electricity outage.
As for equipment i believe more equipment require more maintenance and more chance of failure
I honestly believe "Less is more" .....

This is my 190 liter tank running even without a sump

This is my 3100 liter panoramareef running with only a relatively small sump