Sump Size for Multiple Tanks

[PugsAndFish]

I am starting to plan my next build, which will be a display tank + a frag tank draining into a shared sump. I haven't decided on the sizes of the tanks and sump because I have yet to move and don't know how much room I'll have. Nevertheless I think planning preemptively will be useful.

The display will be no longer than 48". I may keep my Red Sea Reefer 170 to use as the display, but I am leaning towards a traditional 40 breeder or 75 gallon. I don't like the 90 gallon dimension and a 120 gallon seems a bit intimidating at the moment.

The frag tank will be a 30 gallon breeder (36 x 18 x 12) which I already have or one of those 60 gallon Deep Blue / Seapora tanks that are 48 x 24 x 18.

So I have a few questions about sumps...
1. Is there a minimum sump size? The smallest one I am considering (just for the sake of saving some room) are those 26" Trigger sumps or a 20 gallon long DIY sump using the Fiji Cube baffles.
2. Would a 40 gallon breeder sump (or something of a similar size) be enough to handle the volume of 2 tanks? I don't think I'll be able to go above a 40 gallon breeder sump.
3. Is there a benefit to using premade sumps like the Trigger ones over the DIY ones?

 

[Dom]

I don't think it is the size of the sump that is important. I think the only thing that matters is that it is large to comfortably house the necessary equipment.

So when planning, don't think of it as multiple tanks. Total the capacity and then be certain that your hardware (for example, your skimmer) is able to support the total volume of water.

Example: If you have a 75 gallon DT and a frag tank that is 50 gallons, think of it as a 125 gallon tank and plan accordingly.

 

[James77]

Not really a minimum size for function, as long as it comfortably houses all your equipment.

The major thing to consider for size is if the sump will handle all the drain water from the main tanks in case of power failure. Calculate that carefully and add a bit of a buffer. What type of drain system greatly affects that.

With a standard 75 a good 6-7 gallons could fall back into the sump from the pipes and overflowing until it reaches the lowest level on overflow.

Edit:
The premade sumps are great for appearance and fancy baffle systems. You can easily build a sump for much less that will hold more volume and be just as effective.

I ran a 40 breeder sump on my 120 for years. It did fine and had enough to hold overflow water from mabe a smaller tank on top. I also ran a 55g sump on a dual 75g/175g setup and it did well, though the 12" width was limiting.

 

[Dom]

Not really a minimum size for function, as long as it comfortably houses all your equipment.

The major thing to consider for size is if the sump will handle all the drain water from the main tanks in case of power failure. Calculate that carefully and add a bit of a buffer. What type of drain system greatly affects that.

With a standard 75 a good 6-7 gallons could fall back into the sump from the pipes and overflowing until it reaches the lowest level on overflow.

Edit:
The premade sumps are great for appearance and fancy baffle systems. You can easily build a sump for much less that will hold more volume and be just as effective.

I ran a 40 breeder sump on my 120 for years. It did fine and had enough to hold overflow water from mabe a smaller tank on top. I also ran a 55g sump on a dual 75g/175g setup and it did well, though the 12" width was limiting.

Good point. The sump should be able to contain water that back flows if power fails. I’ve always used check valves, but I’m all for multiple safe guards.