Gravity ATO

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$17.99 $17.99

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The IceCap Gravity ATO is a compact and simple auto top off solution for those wishing to replenish evaporated water in their aquariums without dealing with pumps, sensors, or power cords.

  • No electricity required for operation
  • Ideal for small aquariums or sumps
  • Simple to set up and operate


How It Works

Simply screw the reservoir bottle onto its base and mount it to your tank rim.When the water level drops to reveal the shorter tube, the water in the bottle automatically flows into the tank do to the pressure difference-- no electricity required!



  1. Select a suitable mounting insert for the tank's thickness and insert it into the groove on the Gravity ATO Base.
  2. Cut the tubing to the proper length based on the desired water level. There should be a long tube and a short tube, both cut at a slant. Insert the two tubes onto the Gravity ATO Base.
  3. Thread the bottle into the base and install it onto the rim of the fish tank.
  4. Adjust water level as needed to ensure both tubes are in the water. Over time, the Gravity ATO will replenish evaporated water when the water level falls under the shorter tube.


What's Included

1x Gravity ATO Base

3x Mounting Inserts for various rim sizes

1x 500 mL Reservoir Bottle

Silicone Tubing

More Information
UPC 6972809520826
Max Tank Thickness 3/8 in.
Included Mounting Hang On/Bracket
Control Type Preset Plug & Play (No Controls)
Pump Included No
Additional Notes Fits rims ranging from 3mm up to 10mm in thickness
Water Level Detection Gravity-Based
Total Volume 500 mL
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Product Questions

How high does it sit above the aquarium? My tank is under my cabinet so I need something on the shorter side.
Question by: Leann on Mar 5, 2023, 7:10 PM
Thanks for the question! This will sit roughly 7" above the rim of the tank when mounted.
Answer by: Kyle Thomas (BRS Staff) on Mar 23, 2023, 3:49 PM
Will this fit a cheap 5 or 10 gallon tank rimmed tank from a big box store (aqueon or Marineland, for example). Purchased a similar one of Amazon for half the price, but it didn’t fit the kid’s betta tank. I’d love to get this for her if it would work!
Question by: Richard on Apr 14, 2022, 2:37 PM
Thanks for the question! This ATO can fit rims ranging from 3mm up to 10mm in thickness. If your rim is within these ranges, it should work well for your application!
Answer by: Kyle Thomas (BRS Staff) on Apr 14, 2022, 3:53 PM