confused on ATO

[Aqua_expert19]

Im looking to upgrade my tank to a 125 with a sump. I would like to add an ATO but i just dont understand how adding the water to the sump would keep the main displays water level up. if you are pumping a constant volume of water from the sump to the display, adding to the sump would make the sump level rise and not the main display.

I'm sure I misunderstand this but if anyone cares to explain that would be awesome.

 

[mets17127]

The sump does the raising and lowering. The dt stays constant. Think of the sump as the engine driving the system. Evaporation of freshwater drops the volume in the sump

 

[djbon]

Your sump will act as a buffer, your display tank level will remain the same as long as your overflow system capacity match up with your return flow from the sump. If you don't top up your sump, your return pump will run dry once the level is below it's minimum water level.

 

[ktownhero]

I would recommend taking the time to better understand how overflows work before doing anything. It's really important to understand exactly how it works so you can avoid disasters.

That said, the only water that overflows into the sump is the volume pumped from thr sump itself. Therefore, the tank water level never changes because the sump constantly keeps it topped up. Evaporation loss manifests itself in the sump, so that's where you check your level and add water when necessary.

Sent from my XT1575 using Tapatalk

 

[Sk8r]

It's a matter of total water in the system; when you add a 30 gallon sump to a 100 gallon tank, your water volume (not swimming space) is now 130 gallons, and chemically behaves like it, for all dosing, etc, (give or take rock space.) When water leaves the system through evaporation, your return pump will keep the dt constant in level, but the deficit will show up ONLY in your sump, because that pump is sending up what it's got at the same rate as always. This means the sump level will fall. You add new water only to the sump, and it will raise that level to normal. Attach an ATO and it will add new water slowly and often, from an, oh, five gallon to 50 gallon reservoir, by the tablespoon, not the gallon bucket. THis is how you can go away on vacation for two weeks and not come back to the Dead Sea salinity in your tank.

 

[Bent]

There is a pump in the sump pumping water out of it and into the display.

 

[Sk8r]

And there is another pump in the ATO reservoir sending water 'on call' to the sump.

 

[Greybeard]

I've seen this sort of question over and over... never seen a really good explanation of how it actually works.

In a balanced tank/sump system, the tank is full. Any additional water put into the tank causes an equal volume of water to run over the overflow and down to the sump. Tank remains 'full'.

In the sump itself, you likely have several compartments, separated by overflow walls. When running, all of these compartments will also be full, just like the tank, any additional water runs over the walls, and on to the next compartment.

The only section of a running system where the water level varies is in the return pump compartment. This section is not 'full'... and the only way water can get out is for it to be pumped into the display... which is 'full', remember?

All of the other sections of the system overflow, by gravity, when they're full... water level in these containers is set by the height of the overflow. Yes... water height in all of these sections will raise slightly when running, a 1/4" or 1/2" above the overflow entrance. There's a slight delay, based on viscosity, inherent in the system. Still, thinking of these sections as 'full' makes it easier

Whatever volume of water is 'left over' when these sections are full is in the return pump compartment, where it is being pumped to the display tank. As it enters the tank, it causes an equal volume to fall through the overflow, causing an equal volume to fall over each partition wall in the sump, eventually back to the return pump compartment.

So... evaporation will cause the level in the return pump compartment to fall. Everything else is 'full'. That's where your float valve/switch needs to be. If you were to dump an extra gallon of water into the display tank, say... when adding a new fish... the water level in the return pump compartment will rise. Everything else stays the same.

In a well designed system, the sump should be able to handle whatever volume of water falls through the overflow when the pump stops, and the return pump compartment should be small enough so that it doesn't contain enough water to overflow the display tank, should the overflow become plugged.

Everything in balance Am I making any sense here at all?

 

[LJLKRL]

Isn't the purpose of the ATO to keep the salinity at the correct level by adding fresh water back to the system? As the fresh water evaporates the salinity rises, correct? It also maintains the water level (height), but I thought the main purpose was the salinity stabilization.

 

[JMorris271]

That is a major reason. To keep all of the levels correct.
The only fluctuations that can occure is when additional water is added to your sump via a defective ATO system that adds too much or too little water into the sump.

 

[Sk8r]

Water level will sink due to evaporation (a gallon a day from a 50 gallon) and this will simultaneously concentrate salt levels to unfriendly extremes. An ATO replaces with fresh water the water lost due to evaporation. [Salt does not evaporate.] This has the effect of both maintaining the water level in the sump and maintaining an even salinity throughout the system. It accomplishes this by a float switch---not dissimilar to what causes your toilet to fill the tank after a flush. My own system has a 32 gallon Brute trashcan full of ro/di, and a small Eheim pump, connected to a float switch, which detects any fall in water level and automatically turns on the Eheim pump to shoot a few tablespoons of fresh water into the sump via a separate small hose. Think of evaporation as the 'flush' and the ATO as the float switch and refill.

 

[Aqua_expert19]

Hey thanks for all the replies!!!!

This is actually going to be an upgrade for my freshwater planted tank. I currently just dont have the time for salt. I just want to make it as nice as possible and maintenance free as possible.

The overflow i was looking at is the synergy reef bean animal overflow but unsure of which pump to get for the return. Im aiming for quiet and reliable. Im not sure how to size to get. Im looking for a gentle flow across the whole tank. Ill prob drill the over flow in the middle and have returns on each side. Since its planted and not a reef i dont need crazy flow. The sump im thinking of is an eshopps rs200/300.

Im trying to do all my research well in advance of purchasing.

Thanks again for the help. I go on business trips all the time and i like to automate the tank as much as possible. I have an apex,dosing pumps for ferts, full dual stage regulator for co2 i just despise canister filters

 

[CStrickland]

Here's a good primer on sumps http://www.melevsreef.com/node/710 and it has an animation of the water flow too. There's also links to more good info in there.

 

[RussWalters]

I've seen this sort of question over and over... never seen a really good explanation of how it actually works.

In a balanced tank/sump system, the tank is full. Any additional water put into the tank causes an equal volume of water to run over the overflow and down to the sump. Tank remains 'full'.

In the sump itself, you likely have several compartments, separated by overflow walls. When running, all of these compartments will also be full, just like the tank, any additional water runs over the walls, and on to the next compartment.

The only section of a running system where the water level varies is in the return pump compartment. This section is not 'full'... and the only way water can get out is for it to be pumped into the display... which is 'full', remember?

All of the other sections of the system overflow, by gravity, when they're full... water level in these containers is set by the height of the overflow. Yes... water height in all of these sections will raise slightly when running, a 1/4" or 1/2" above the overflow entrance. There's a slight delay, based on viscosity, inherent in the system. Still, thinking of these sections as 'full' makes it easier

Whatever volume of water is 'left over' when these sections are full is in the return pump compartment, where it is being pumped to the display tank. As it enters the tank, it causes an equal volume to fall through the overflow, causing an equal volume to fall over each partition wall in the sump, eventually back to the return pump compartment.

So... evaporation will cause the level in the return pump compartment to fall. Everything else is 'full'. That's where your float valve/switch needs to be. If you were to dump an extra gallon of water into the display tank, say... when adding a new fish... the water level in the return pump compartment will rise. Everything else stays the same.

In a well designed system, the sump should be able to handle whatever volume of water falls through the overflow when the pump stops, and the return pump compartment should be small enough so that it doesn't contain enough water to overflow the display tank, should the overflow become plugged.

Everything in balance Am I making any sense here at all?

Great explanation! :bounce2:

 

[Greybeard]

Great explanation! :bounce2:

Thanks