Open water surface area per gallon? Recommendations?

[Mandelstam]

I know there's a big need for open water surface for gas exchange in our tanks. But is there any kind of guidelines for how much surface area is needed for different sized tanks? Is a non covered display tank enough (sump+fuge, etc, covered). I know a skimmer makes a big difference here.

Just curious as there's a potential for lowering evaporation inside the stand and also lowering heat loss.

 

[sundog101]

I’ve never heard of an open surface area rule. As long as you have good surface agitation and water movement you should be good. Plus a skimmer helps.

 

[Mandelstam]

I’ve never heard of an open surface area rule. As long as you have good surface agitation and water movement you should be good. Plus a skimmer helps.

I've never heard of any either but I've seen people caution others to cover "too much" of the system. But I've also seen others with completely covered sumps. My gut tells me that as long as my display is open and well agitated it should be ok. But my gut has been known to be wrong before lol.

 

[sundog101]

FWIW, my display is completely covered with a glass top and I haven’t seen any problems. The sump has good agitation though, along with a skimmer and vent fan in the cabinet.

 

[ca1ore]

Gas exchange is a function of surface area and the extent to which oxygen depleted water is moved to the surface. All things equal a tank with lower surface to volume ratio needs higher water movement, and will be more vulnerable to o2 starvation in the event of power loss. The issue with covered tanks is gas buildup in the stagnant air above the tank or sump, though I'd imagine most covers allow enough air movement in and out to mitigate this. I use glass/pvc panels over about half of the surface areas of my sumps and display. No science to it, just 'seemed' about right to me.