What Size Sump Do I Need/Should I Buy?

[tbrown]

Ok, so let me start out by saying this is my first ever article so please be patient and please be kind. I always enjoy constructive criticism so feel free to provide any you may have!

Usually, when I need information I go to the old Google machine to provide me with the answers I seek. However, sumps are something that the math just doesn't math for me. Lots of websites use the 10% or 20% or 25% of display tank volume for your sump size. But what if my 110 extra high tank doesn't have room for a 29 gallon tank under the stand? And does my 110 gallon tank require a bigger sump than my 90 even though they're the same footprint?

The short answer is no.

The way I look at a sump is two fold:

1. The footprint needs to be enough to handle any equipment you will be adding to the sump
2. The sump has to be able to handle the additional water that will enter from the display tank anytime power is cut to the return pump

Both of these require a sump footprint, not a total gallon of space.

For example a 100 gallon tank, using the 20% for sump size would require a 20 gallon sump.

Would that be a 20 tall or a 20 long?

Well, that's where footprint would come into play. A 20 tall has a footprint of 24" by 12" and a 20 long has a footprint of 30" by 12".

The 100 gallon tank has a footprint of 48" by 18" so either tank would fit underneath just fine.

However, if you were using a 20 tall, for every 1" of drop in the display tank after the return pump shuts off, the sump has to be able to handle 3" if rise across the entire sump, whereas with the 20 long you'd only require a 2.4" rise per inch from the display tank. This means that the 20 tall has to be run at a lower level from the top of the sump to handle any extra water draining from the display tank.

But what if I'm running a peninsula tank?

The IM 100 Peninsula has a footprint of 48" by 30". Still, either of the 20 gallon tanks can fit underneath comfortably, but can they handle the flow?

Using the same math, now the 20 tall requires 5" for every 1" of drop in the display tank whereas the 20 long only requires 4".

It still doesn't seem like a big difference between the two sumps but look at the difference the surface area of the tank made without even increasing the gallons of the tank.

When determining what size sump to go with, the old adage "Bigger is Better" is definitely fitting. You should always go with the largest sump you can comfortably fit under (or beside) your tank. But when calculating how small is too small, consider the surface area of your tank as more important than the gallons of your tank.

The simple formula I use to determine how many inches of headspace minimum needs to be in my sump to avoid overflowing in a power outage situation is:

DT Sump
(LxW) ÷ (LxW) = inches required in sump per inch of drainage from the DT

I hope this is helpful for someone!

 

[toi_ss]

Great article! I tend to account for a 15-25% display volume refugium then all the minimum space for my equipment like protein skimmers and return pumps. Then I just add a bit more space for anything I want to add later on like reactors. I like to use around 2/3 of my display length for my sump and if the sump is in a cabinet meaning I don't have full open access to it, I won't go deeper than 24" front to back. I really like the idea of having an offset sump with its own seperate cabinet that opens from the front and from the top for full access.

 

[kevgib67]

Excellent article Tim! Very informative and you made it easy to follow and understand!

 

[WalkerLovesTheOcean]

Very nice for your first article Tim! I am sure this will help a lot of people. You made it very simple to understand. Nice! :)

 

[tbrown]

Thanks!

 

[Idech]

Sump should be able to handle water from display when pumped turned off + water from the pipes + ideally water from the rodi reservoir, in case it overflows.

Go as big as needed to achieve that and run the equipment you need.

 

[billyocean]

Good job Timbo

 

[WvAquatics]

This is my setup 60 breeder half fuge rest for equipment

 

[Cichlid Dad]

Thank you good article. For my setup I run no socks and only a skimmer. So my 75 gallon and now my 120 I'm cycling now have a 40 breeder " refugium" with just a corner baffle for the return and ATO. I couldn't fit it under my 75 so it sits beside the tank. For the 120 , I did the same thing because I like the ease of maintenance.

 

[steveschuerger]

Nice write up Tim . If I ever have a tank that need a a sump I’ll try to remember this article.

 

[tbrown]

Typically the 20% should work but some of those taller tanks make it difficult to fit the 20% under the stand but 20% in a tall tank may be overkill unless you're running a large skimmer or a reef mat while on a shallow, long tank the 20% may not be enough to handle the additional flow handling requirements.

 

[markfmvl]

I just went with a 40 breeder sump for my 90 and just put it next to the tank.. It gives me more refuge space and room for my skimmer and return pump. I previously had a 20 long

 

[tbrown]

I just went with a 40 breeder sump for my 90 and just put it next to the tank.. It gives me more refuge space and room for my skimmer and return pump. I previously had a 20 long

Definitely! Go as big as you can. I ended up with a 40 on my 125 and only a 30 on my 70. Those were the max size that fit under the stand.

 

[Cichlid Dad]

Here's the 120 and 40 breeder I was cycling on post 9 Turning out to be a great setup. @markfmvl I would love to see a picture when you have it all done

 

[allenk4]

Ok, so let me start out by saying this is my first ever article so please be patient and please be kind. I always enjoy constructive criticism so feel free to provide any you may have!

Usually, when I need information I go to the old Google machine to provide me with the answers I seek. However, sumps are something that the math just doesn't math for me. Lots of websites use the 10% or 20% or 25% of display tank volume for your sump size. But what if my 110 extra high tank doesn't have room for a 29 gallon tank under the stand? And does my 110 gallon tank require a bigger sump than my 90 even though they're the same footprint?

The short answer is no.

The way I look at a sump is two fold:

1. The footprint needs to be enough to handle any equipment you will be adding to the sump
2. The sump has to be able to handle the additional water that will enter from the display tank anytime power is cut to the return pump

Both of these require a sump footprint, not a total gallon of space.

For example a 100 gallon tank, using the 20% for sump size would require a 20 gallon sump.

Would that be a 20 tall or a 20 long?

Well, that's where footprint would come into play. A 20 tall has a footprint of 24" by 12" and a 20 long has a footprint of 30" by 12".

The 100 gallon tank has a footprint of 48" by 18" so either tank would fit underneath just fine.

However, if you were using a 20 tall, for every 1" of drop in the display tank after the return pump shuts off, the sump has to be able to handle 3" if rise across the entire sump, whereas with the 20 long you'd only require a 2.4" rise per inch from the display tank. This means that the 20 tall has to be run at a lower level from the top of the sump to handle any extra water draining from the display tank.

But what if I'm running a peninsula tank?

The IM 100 Peninsula has a footprint of 48" by 30". Still, either of the 20 gallon tanks can fit underneath comfortably, but can they handle the flow?

Using the same math, now the 20 tall requires 5" for every 1" of drop in the display tank whereas the 20 long only requires 4".

It still doesn't seem like a big difference between the two sumps but look at the difference the surface area of the tank made without even increasing the gallons of the tank.

When determining what size sump to go with, the old adage "Bigger is Better" is definitely fitting. You should always go with the largest sump you can comfortably fit under (or beside) your tank. But when calculating how small is too small, consider the surface area of your tank as more important than the gallons of your tank.

The simple formula I use to determine how many inches of headspace minimum needs to be in my sump to avoid overflowing in a power outage situation is:

DT Sump
(LxW) ÷ (LxW) = inches required in sump per inch of drainage from the DT

I hope this is helpful for someone!

When considering Sump volume and suggesting 20% of the volume of the tank….why isn’t the actual water volume of the sump used for the calculation?

A 20 gallon sump doesn’t hold much water when it is not completely filled and contains a skimmer and other stuff that decreases actual water volume. I suspect the ratio is actually suggests a 100 gallon display tank requires a 40 gallon breeder with 20 gallons of water in it.

 

[tbrown]

When considering Sump volume and suggesting 20% of the volume of the tank….why isn’t the actual water volume of the sump used for the calculation?

A 20 gallon sump doesn’t hold much water when it is not completely filled and contains a skimmer and other stuff that decreases actual water volume. I suspect the ratio is actually suggests a 100 gallon display tank requires a 40 gallon breeder with 20 gallons of water in it.

That's actually the argument I made against the 20% rule. However, how much water is in the sump is irrelevant, it's how much water is NOT in the sump to make sure there's enough headspace available in case power shuts off. The amount of that headspace required will be significantly less on tall tanks than on peninsula tanks that are long and wide vs tall and skinny.

 

[allenk4]

That's actually the argument I made against the 20% rule. However, how much water is in the sump is irrelevant, it's how much water is NOT in the sump to make sure there's enough headspace available in case power shuts off. The amount of that headspace required will be significantly less on tall tanks than on peninsula tanks that are long and wide vs tall and skinny.

My water volume thought was more focused on what the sump is designed to do regarding O2 exchange and dilution of bad stuff in the water.

I’m not too concerned with being able to calculate the volume of water returning to the sump from the DT and associated plumbing, if the return pump fails.

Curious how much water is actually in the average Sump vs DT volume.