1 overflow or 2

[NC Reef Guy]

I am in the process of purchasing my new tank and stand. I have inquired at two local shops for my tank. One says that I should get a tank with two overflows and the other says that one would be sufficient and to use the koralia blowers instead. I really have no idea which would be better. Any thoughts?

 

[padgett152]

it all depends on how much water you want to turn over in an hour. i have a 75 g w/ a 20 long sump/fuge and only turn over 300 gph. probably the minimum for a tank my size but for right now, it all works fine.

 

[NC Reef Guy]

what would be the suggested turnover for a 120?

 

[HOBrien]

It depends on which Corals and fish you plan to keep as well.

 

[james3370]

<a href=showthread.php?s=&postid=14558735#post14558735 target=_blank>Originally posted</a> by NC Reef Guy
what would be the suggested turnover for a 120?

3-5x tank volume for actual flow thru sump & tank return is the general concensus

total tank flow is generally somewhere around 20-30x tank volume by combination of sump return, closed loop &/or powerheads in the tank

 

[drparker]

For the same volume of water the more surface area that is overflowed the better. One big one or two little makes no difference just get as much surface area as possible. This will remove a thinner layer off the top, and increase the efficiency of your skimmer because DOCs build up in the very top layer.

 

[NC Reef Guy]

so dual overflows with mag 7's on the returns should be adequate ? should I also have a powerhead in there as well?

 

[danorth]

Built in overflows are better than hang on ones....can't tell which ones you are talking about...but if they are hang on ones make sure the return is strong enough to keep the air bubbles from building up. I am having that problem right now since I added a second hang on.

 

[NC Reef Guy]

I am talking about built ins.

 

[petedoc]

Dual overflow have another advantage, if one is partially plugged you won't have an immediate disaster. Also less volume of flow through each unit decreases turbulence and noise. Mag 7 is perfect, plenty of flow. Additional in tank pumps may be added as needed. Do not try to get all of your flow from the sump system.