Advantages of an ATO?

[DamianOZ]

May be this will help you comprehend... or maybe not... either way, cheers
http://www.engineeringtoolbox.com/evaporation-water-surface-d_690.html

 

[ash9965]

My guess would be the reservoir is above the sump or tank and gravity fed once the float valve opens.

Exactly right just go to ebay and look up float ATO valve lots of choices I have the reservoirs on a side table with 1/4 inch tubing running to float valve in sump and as the water in the tank goes down the floater valve opens up allowing the level to stay consistent..

 

[Kami2011]

It keeps you waters salinity stable and makes it so you don't have to worry about evaporation

 

[fry_school101]

If you aren't wanting SPS, you will probably be fine without. Most of my corals and fish have handled manual topoff without issue, but the ATO is much more convenient.

 

[Maritimer]

I've got a 65gallon with everything over-the-rim. Bought an ATO months ago, and haven't set it up yet, as I came downstairs one morning to find the tank slightly over-full and the sump fairly empty, with the return blowing a mist of bubbles . . .

The air-hose connecting the overflow box to the Tom's lift-pump had grown algae inside, and the overflow was reduced to a trickle at most. Had the ATO been installed, I worry that would have flooded the system with RO/DI, and the floor with brackish water.

Every system is different . . .

~Bruce, FWIW

 

[Lionfish Lair]

I LOVE an ATO. I try to put one on every tank I have because, just for ease of use. No it's not hard to add it by hand every day, but it's a beautiful thing when you don't have to think about it.

 

[Waterjockey]

When I first set my tank up, I was filling the sump daily manually with a line from my RODI to my sump with a manual shut off valve. Even with a small system like mine, it takes a fair bit of time to top up the sump a half gallon to a gallon a day. One evening I forgot I was topping up the sump and went to bed. When I woke up in the morning, the carpets on the main floor were soaking wet, water was pouring down into the basement. I lost every coral I had, a few fish survived the near pure freshwater tank I had. Nothing like trying to save what you have left in half a panic first thing in the morning, not to mention the financial loss from inattention. The next day I had installed a rudimentary ato, and the peace of mind has been priceless. Not to mention if we go away on vacation from a few days to weeks, I don't have to worry about how I am going to keep the tank topped off (I have redundant switches and alarms tied to an apex now). After my skimmer, it's my favorite piece of equipment. I would never run another tank without one.

Cheers!