Two 20L sumps under 125 gallon

[DeltaBorne]

Hello!
I currently have two 75 gallon reefs that I want to combine into one 125. Both 75’s have eshopps PF-1200 hang on overflows plumbed where one drain is an emergency overflow. Sump on each is a 20L aquarium. I was hoping to just slap both 20L’s under the new 125 and have two sumps running the same as they were in the 75’s. So essentially having the 125 plumbed as though I put the two 75’s next to each other. My question is, does anybody see or have experienced any issues with this that I may be overlooking? For reference both 75’s are identical in pumps, plumbing, lighting, etc. thank you for any and all help!

 

[Michael Hughes]

Just to clarify, each sump will be connected independently to the 125 DT via it's own HOB overflow?

If that's the case, I wonder if there is a scenario in which the flow rate through the HOBs could end up diverging from each other, such that one sump ends up getting more flow than the other? In this case, assuming the return pumps in each sump are producing the same gph, I might be concerned that one sump would empty slowly over time and the other would get more full over time. It seems like balancing flow rates could be a nightmare. Just thinking out loud...

 

[DeltaBorne]

Just to clarify, each sump will be connected independently to the 125 DT via it's own HOB overflow?

If that's the case, I wonder if there is a scenario in which the flow rate through the HOBs could end up diverging from each other, such that one sump ends up getting more flow than the other? In this case, assuming the return pumps in each sump are producing the same gph, I might be concerned that one sump would empty slowly over time and the other would get more full over time. It seems like balancing flow rates could be a nightmare. Just thinking out loud...

Yeah they would be independent of each other, thank you for thinking out loud these are the what ifs that have me posting here

 

[DeltaBorne]

I have ball valves on both drain and return pipes that I manipulate to get the balance I need so I don’t get any gurgle from the overflows. I wonder if that plus an upside down U pipe connecting the two sumps would work, a U pipe like the one drawing water from the tank to the overflow box, siphoned with water.

 

[Michael Hughes]

If you're going to connect the two sumps together with water siphoning from one to the other, you might as well make it a unidirectional flow where both HOB overflows empty into one 20L, then the return pump is in the other. This would probably work best if you drilled both tanks (which shouldn't be a problem for a 20L) and connected them with a PVC pipe wide enough to handle all the flow...