return above or under

[Basile]

I'm in the process of doing putting my plumbing together and for my return i'm undecide, i've seen people do either their return above the water churning the water line and some plunging it under the waterline. My tank is rimless and without canopy so that in mind i was thinking a screen on top that i take off when i have guest. If so it would mean above water no? How's your set up and why? Plus is having your return churning the surface of the water a plus for gas exchange?

[Aquattro]

Having above the water will cause a lot of splashing and salt creep. Assuming you run a skimmer, that should be enough for O2 exchange.

[AdamsB]

I would go below the water surface. Otherwise It'll cause a lot of splashing as Aquattro said. Also If your power goes out and water drains to the sump, once the pump turns back on you'll get quite a bit more splashing till things even out again. I'm thankful for my glass lid. I had the loc line 4 inches below the water surface pointing up. Power went out, came back on 5 mins later and pounded my glass lid. That would have been a wet carpet and dry sump. Although I anticipated it, it's nice to see it in action an know if I'm not home things will be fine.

So consider what happens during water changes, power cuts etc. and remember, salt water will permanently stain drywall.

[sphelps]

For a rimless tank, through the back glass below the water level which is usually the closest to the top the builder is comfortable drilling.

[LoJack]

Yeah you gotta go underwater, above will make such a mess. You'll be cleaning up salt twice a day

Your overflow and your skimmer will do a fine job of O2 exchange and breaking up the protein film on the surface.

[kien]

Drill your return into the back wall and slap a loc-line onto it. This way you can adjust the return and play around with it by moving it above the water line and below the water line. Who knows, maybe you're the type of person who likes having salt water splash all over the place and salt creep all over your lights and the front of your glass? If you're not, then you can easily move the loc-line below the water surface :-)

[IanWR]

Originally Posted by kien

Who knows, maybe you're the type of person who likes having salt water splash all over the place and salt creep all over your lights and the front of your glass?

Is it weird that I actually laugh out loud at many posts and replies here on canreef? Kien, I have to give you a shout out as someone who consistently makes me smile while keeping me informed. Keep up the good work chum.

- Ian

[mark]

no problem below the water level if you sump has enough room for when your pump stops

[gregzz4]

I can't vote as I have my returns semi-submerged and the loc-line is horizontal
High enough for some surface agitation, but low enough to not splash or create noise

[kien]

Originally Posted by gregzz4

I can't vote as I have my returns semi-submerged and the loc-line is horizontal
High enough for some surface agitation, but low enough to not splash or create noise

Interesting. So would you say that you swing both ways then?