Water level in ATS (Newbie question)

[caponet]

Hello,

I've been reading as much as possible on this forum and others, but I'm still confused with a simple thing.
I'm sure that It will be obvious by all of you but, how do you keep your water level constant in your sump, refuge,
ATS?

I'm new to marine tanks (right now I'm still focused on freshwater planted tanks), so I've never had that problem before.

I want to feed my ATS with an overflow box and then return the water to the main tank with a pump, so I guess that I need the overflow flow to be the same as the pump flow in order to prevent an overflow either of my main tank or in the ATS.

I'm I missing something? How do you adjust the flow?

Thank you

[rygh]

Well, the lowest point, usually the sump, will not be constant.
You can keep it fairly stable with automatic top-off, but water level will go up and down as pumps go on/off.

Everything else is kept at a constant height by the height of the overflow.
Water goes over the edge, so stays at exactly that height.
The edge can be a fancy weir, or just the lip of a pipe.
In an ATS, if you have a vertical pipe exit, it will be at the level of that pipe opening.
Key there is to make REALLY sure that water through those pipes, which is gravity fed, so low pressure,
can handle more than the return pump.

[sklywag]

That will be determined by how much you fill it and run it at.
I'm currently tunning a horizontal ATS. My sump/fuge level runs between 6 and 10 inches. I only have an ATO that ads water when it drops to the 6 inch level and maintians that for a few days after evaporating down from the 10 inch mark after a few days. Depending on evaporation.
I am planning(slow to act) a verticle ATS in which I'll drop my water level down to start at about 8 inches(giving me a 10 inch tall screen) and then evaporate down to about 4 inches before ATO kicks in to keep level above pump to avoid vortex. I don't have an ATO that kicks on and off. Only on depending on a single float valve.

Or if your thinking is that the overflow will overflow too much and your return won't keep up. That won't happen because the return pump will determine flow through sump back to the display and over the overflow. If it's a built in overflow box, the water level in tank has already been predetermined. If a HOB overflow, you'll have to adjust the inside box to the hiegth you choose to run display at.
Make sense?

[caponet]

Thank you!

Well, I think that I'm getting the idea... Although it's a bit difficult to visualize it, I think that I'm ready to build and test my first overflow box and ATS. I'm not going to use an auto top off system because I'm planning a closed setup so there won't be a lot of evaporation.

By the way, my new aquarium will be a mediterranen biotope one, so I'll keep you informed with the ATS performance with it.

Regards!