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Marine Depot Auto Top Off ATO w/ Pump and Two Magnetic Sensors

Marine Depot Auto Top Off ATO w/ Pump and Two Magnetic Sensors


Item #: MD88503

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Easy-to-use auto top off system that is ready to go out of the box!

Includes two float sensors with magnetic mounting brackets and top-off pump.

The float sensors are enclosed in a protective acrylic enclosures to prevent snails or debris from interfering with the sensor.

  • 5 ft power cord
  • 4 ft sensor cord
  • Includes 3 ft of tubing

Manufacturer information

Marine Depot was started in 1998 by a self-professed reef geek and pre-med student Ken Wong. Ken envisioned a one-stop shop where customers could find everything they needed, from technical product specifications, reef aquarium information, expert advice on the hobby and friendly one-on-one customer support. Having grown from a one-man crew to being one of the world’s largest suppliers of reef and marine aquarium products, this very core philosophy still lives strong in the Marine Depot culture 20 years later.

4 Stars


Reviewed on
December 02, 2018

No, I would not recommend this.

Dies after 48 hours

Pros: Small, easy to assemble/use

Cons: Don't know if i got a lemon, but for the price it should last more than 2 days. Expected better from Marine Depot product

Was easy enough to put together, worked great for about 48 hours, and now it appears to be dead

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Reviewed on
June 12, 2018

Yes, I would recommend this.

Does its job

Pros: Works as is, 2 floats, easy to install & use

Cons: Would like to see thicker acrylic/plastic used

Have been running this on a aio Reef less than a month with plans to put it on a 50g sumped system. I have not had any issues with it st all, and does what it’s suppose to do. With routine maintenance I do not fear any malfunctions, I have used similar setups before for years (jbj) without issue. 4 stars due to feeling a little flimsy, but nothing to fret over.

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Reviewed on
May 02, 2018

Yes, I would recommend this.

Nothing much to it it's simple but it works

Pros: Cheap (could be cheaper considering craftsmanship of what it actual is though) you could make this kit yourself cheaper

Cons: Instructions were terrible. One of the floats acrylic is bent slightly inward making the float not stay straight up and down, I don't know what the acrylic part is on top but the tub supplied doesn't fit through it.

I ordered the dual float sensor version, put one in the sump one in the bucket so your ato pump won't run dry if it runs out of water. Out of the box it seems pretty simple and cheaply made. It came with a tube, pump and dual sensors with "control" which is just a simple plugin. The "instructions" were terrible and it was just a copy of a page, the bottom half didnt' copy well so I can't read it. It's pretty self explanitory except one thing. On the top of one of the floats there is an acrylic piece with a hole in it and a screw. Now I'm assuming they ment for this to hold the tube so that it would stay in place to top off your tank/sump. The other sensor didn't have one on it. I guess that's fine because it's going upside down in a bucket but I'm not sure if it was mean to have it or not. The one without the piece on it sits a little bent inward so I had to stick something behind the magnet to make it stand at a 90 degree angle (up and down.) The tube supplied wasn't cut smoothly it looks like they sawed through it with a jagged knife lol. I don't know just litte stuff makes this kit seem cheap. The pump is very very tiny. We will see how this holds up. I wish they had some pictures of a system together or a video or better instructions because I don't get the little acrylic piece - the tube supplied is too big to fit in it so I don't know if ther's another purpose for it or what. None the less I set this up in like 5 minutes with a 5 gal bucket under my stand next to the sump and I tested it. Only time will tell how it holds up.

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Reviewed on
February 07, 2017

Yes, I would recommend this.

Excellent ato

Easy to install and after 2 months it continues to work flawlessly. I ordered the 2 float switch model (highly recommend in case you forget to refill the top off tank) but only one float switch was in the box. After a quick call to marine depot I had a the 2nd switch 4 days later. Excellent ato system and great costumer service.

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