I've got my first saltwater tank set up testing all the various bits with water, and i'm finding that maybe my 10gal sump (for a 65-gal tank) isn't quite big enough. Everything works, and I can dial in the return so that it stays in balance, but I'm a bit afraid that I'm going to wind up with a wet floor because the tolerance is pretty narrow - by which I mean, while it's possible to set everything so that when the power goes out there's enough room in the sump to handle all the water draining back, it's also possible (and not even hard, if I'm not paying attention) to set the overflow so that the sump overflows when the power's off. Due to limitations of the stand (there's a big honking support partition right in the middle), I can only fit a 10g sump - so I'm considering adding a second 10g sump on the other side of the stand with the return, and running a 1" (or more) pipe between them through bulkheads.
What I have currently is a two chamber sump; the big chamber, in which I'm intending to put a skimmer eventually (gotta save my pennies), has dual 1" overflow pipes from the main tank set up Herbie-style. For the return, I have a Jebao DCT-4000; running it right around 70% seems to be the sweet spot for balancing inflow and outflow. The problem I foresee is that every time I turn off the return I have little enough "extra" water that I wind up having to tweak things to get the siphon started before the pump has emptied the return chamber - and I'm afraid one of the times I tweak it, it'll wind up in a state where the overflow is submerged enough that if the power goes out, I'll wind up with a wet floor - I think I've got about a gallon, maybe 1.5, of play in the system, and I don't think that's enough.
As I mentioned above, I was thinking about installing a second 10gal. sump on the other side of the partition. Any suggestions about how to partition the second sump, how far off the bottom of the tank to drill, and relative sizing of the return chamber? I imagine I could divide the second tank similarly to the first (see attached picture).
... or about a two-thirds/one-third split - making the smaller chambers (one in each sump) the inflow/return, and connecting the larger chambers to each other with the new pipe - the question being, should the hole be right near the bottom of the tank (I imagine that would be best for flow), or should I put it nearer the expected waterline (about 8" off the bottom)? Should it be at the same level in both tanks? (I imagine yes, but if not, let me know!)
Anyway, this is exciting - I've got a tubfull of formerly-dry rock that's actively processing ammonia (it's been wet for about eight weeks, and I just added ammonia to 2ppm, and it was gone in 36h, and the nitrites spiked and were gone in 48!) and I've cleared the space where the tank will go. Now I just have to solve a couple more problems, and I can set it up in its final home. Hm, I should probably start my QT tank cycling...
What I have currently is a two chamber sump; the big chamber, in which I'm intending to put a skimmer eventually (gotta save my pennies), has dual 1" overflow pipes from the main tank set up Herbie-style. For the return, I have a Jebao DCT-4000; running it right around 70% seems to be the sweet spot for balancing inflow and outflow. The problem I foresee is that every time I turn off the return I have little enough "extra" water that I wind up having to tweak things to get the siphon started before the pump has emptied the return chamber - and I'm afraid one of the times I tweak it, it'll wind up in a state where the overflow is submerged enough that if the power goes out, I'll wind up with a wet floor - I think I've got about a gallon, maybe 1.5, of play in the system, and I don't think that's enough.
As I mentioned above, I was thinking about installing a second 10gal. sump on the other side of the partition. Any suggestions about how to partition the second sump, how far off the bottom of the tank to drill, and relative sizing of the return chamber? I imagine I could divide the second tank similarly to the first (see attached picture).
... or about a two-thirds/one-third split - making the smaller chambers (one in each sump) the inflow/return, and connecting the larger chambers to each other with the new pipe - the question being, should the hole be right near the bottom of the tank (I imagine that would be best for flow), or should I put it nearer the expected waterline (about 8" off the bottom)? Should it be at the same level in both tanks? (I imagine yes, but if not, let me know!)
Anyway, this is exciting - I've got a tubfull of formerly-dry rock that's actively processing ammonia (it's been wet for about eight weeks, and I just added ammonia to 2ppm, and it was gone in 36h, and the nitrites spiked and were gone in 48!) and I've cleared the space where the tank will go. Now I just have to solve a couple more problems, and I can set it up in its final home. Hm, I should probably start my QT tank cycling...
If there was one a little taller, that could work, but there really isn't any room. Petco does, in fact, have the sale - that's where I got this tank! 
