Dual or single over flow

What advantage does a dual overflow offer other than duality?

I can get a 120 single right now or wait several weeks for dual.

I am interested in others opinions

 

I debated this myself, and settled on a single with 1.5" drain. Been up for a few days now, and working perfectly. Mine is 125 gallons.

 

you shouldn't need more flow than what the single would give you. Single is fine. Get it!

 

You shouldn't need more flow, there is no reason to run tons of flow through a sump. Having dual might offer some redundancy though, if one gets clogged for some reason. I think I've only ever seen one clog though, but it was homemade and probably a flawed design (I won't say whose design though ).

 

There is a actually an advantage. More surface area skimmed off the top and the sheet of water being skimmed is thinner. A double is quite a bit more efficient than a single. So it's really not about how much flow you can put through it, it's the fact that it is so much more efficient. This is just like saying "what's the advantage of a coast to coast overflow?"

 

I'm not sure if I agree. If the surface bound organics are turning over, faster than they are being attracted to the air water interface, then it shouldn't really matter. The actual surface area at the air water interface isn't really that large either compared to the surface area of the bubbles in the skimmer. Slower turnover though, will increase contact time with the skimmer, as these molecules will "dwell" longer in the sump. Really though, as your statement is, this is also speculation

 

I didn't think there is that much to gain by having the second overflow. I would rather have more swimming room.

 

I was considering having the drain on one over flow and the return on the other. I could use the other two holes as a closed loop.

I have two mp10es s. I would probably need the flow. I am not sure the mp10's would even work on a 120. The LFS agreed to allow me to trade my 2 mp10s for 1 mp40.

 

I never said anything about heavy flow through the sump. I personally use a very small return pump (1000 gph with 5 ft head) on my 120 gallon tank. I'm a firm believer in slow flow through the sump. I'm also a firm believer in the fact that organics are attracted to air which is why you want the thinnest sheet possible going over the overflow. How do we do this? Increase the total width of the overflow. Like I said, the thinner the sheet going over the overflow, the more efficient the skim. Once again, a single overflow isn't going to hurt anything. I did opt for the double on my 120. When I do an acrylic tank, I will be doing a coast to coast.

 

I did not notice a difference in the boxes from single to double.

It is an aquion tank vs marine land