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Connecting Two Aquarium Systems

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Hi all, I'm pretty new to reefing--have had a 14g biocube for a year or so. Decided to make a small 7 gallon sump and it's running great! Of course as soon as I did that I fell into a used 55 gallon aquarium with a pro clear sump. Good news is I have room for the new aquarium right to next to the biocube. Neither my DIY 7 gallon sump nor the pro clear will be big enough to run a combined ~95 gallon system.

How can I connect the two systems? Each will be on its own stand and I don't think drilling my DIY 7 gallon sump is an option--I would have to tear it down and start over and then have pipes going through the two stands. 

Any ideas?

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Typically, if people are connecting multiple displays, they tie into one sump.


Tieing the sumps together can be tricky, especially if they are both on the same level. You need to consider inflow to each sump when all pumps are off, how much will drain into each sump, and how  the tie-in system will affect levels in both sumps. You also need to consider what will happen when the return pump is off in only one tank, each system will respond differently. What happens if the ATO fails off in one tank? What happens if the ATO fails on in one tank? What happens if the ATO runs dry on both sumps? What happens if multiple things occur that pushes more water into the sump with the smallest reserve capacity than any one condition?

One pump fails, nearly filling the smallest sump and running the larger sump return section low due to the layout of the tie-in system, causing the ATO to run in the large sump. As the ATO fills, what is mostly RO/DI gets pushed to the smaller sump, causing salinity to drop in the smaller system and allowing the sump to overflow. The auto shutoff fails in the ATO (assuming there was one), so the reservoir gets emptied into the smaller system. Salinity bottoms out because you had a larger ATO reservoir so you could go on vacation for a week, which you filled up this morning, immediately before leaving the house.


No idea why I felt the story was necessary, but there you go.


If the smaller sump sits higher than the larger sump, you can match the flow rate from the small sump to the large sump to the rate the biocube flows to the small sump, you can have the biocube drain to the small sump, which drains to the large sump, which is sent back to the biocube by the return pump, which could be separate from the 55’s return pump or have a shared return pump with a valve to throttle flow to the smaller tank. The 55 would drain directly to the sump.

You definately need backup drains and need to run something that will compensates in some way as the flow from the biocube changes. It also shouldn’t have a drain that can loose siphon if it doesn’t have the ability to self start. Trying to tune the sump drain to match the biocube drain with valves would be risky as any changes to the flow rate of the biocube drain would adversly affect the level in the small sump as it cannot compensate very much and would be more likely to clog. It would be better to have the sump drain be slightly faster and potentially noisy. Running larger backup and energency drains that are above the water line of the large sump wouldbe a good idea so you are alerted when there is an issue.


If the systems are close enough to tie together, they could share the sump. You will need space for what backflows from both tanks. I think this will be the most simple, easy, and most reliable way to run it.


If you still really wanted to use your sump (you built it, be proud of it), you could set the sump higher and use it remotely to run media or reactors, possibly use it as a display refugium. Maybe you could modify it to use as a quarantine or hospital tank. You could have both systems plumbed to one tank, but have one of the systems also run to the small sump. There are some risks with this one too.

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