Hydor Smart Level Controller Auto Top Off

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  • Hydor Smart Level Controller

Hydor Smart Level Controller Auto Top Off

87% Recommend this to a friend (13 of 15)

SKU: 207981
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Quick Overview

Keep your aquarium water "topped off" with the Smart Level Controller by Hydor. Easily install the controller in your sump or aquarium. The electronic sensor features LED lights to display miniumum water level, maximum water level and alarm mode. Additionally, an audible alarm will sound if water level reaches alarm sensor. Maximum Pump Power: 50W

To replenish water loss due to evaporation, use a top off pump (sold separately) with a maximum power of 50W. Note that it is best to use a pump that tops off slowly within 10 minutes (maximum topping-off time).

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Full Details

  • Easy to install with no moving parts to malfunction by algae or salt creep
  • Sensor is unaffected by surface movement thus eliminating false alarms
  • Magnet and suction cup included - Mount up to .4" (10mm) thick aquarium
  • Suitable for marine and freshwater applications


Dimensions: 5.75" W x 1" L x 4" H


  • Included: Suction cup magnet mount for sensor
  • Adhesive cable clamp for routing sensor cable
  • Level sensor on 7" long cable



  • Great sock By Jordan on 1/19/2015

    This was my first automated addition to my tank, and works great. Setting up took only a few minutest and has been very reliable. Adjustments are easy and I plan on adding one to my other tanks.
  • Love it mostly By Dennis on 12/29/2014

    I got this because I needed something that didn't have a mechanical switch that constantly went off and on (I hate noises). This is great because it waits til it drops to a certain level, then pumps in water until it reaches another level. The only issue I have is there is a min. pump time that has to run and since my evaporation compartment in my sump is small, it constantly reaches the third sensor which sets off an audible alarm... I may just disconnect the speaker but other than that I love it. Not really a design flaw, if you have a big enough evap compartment you will be fine, mine is just small. It would be nice if it didn't have a min pump time however.
  • A+ By Fred on 12/13/2014

    Great product. best design on the market. Low profile,sleek designand highly efficient. I had been searching for an ATO and hated float switches and bulky sensors. As soon as i saw this, i jumped on it. Glad i Did! works flawlessly.
  • I have mixed feelings about it, By joesreeftank on 10/5/2014

    Easy to install and works like designed, Problem for me is I use it in my 45 gal sump, My home made ATO would keep the water right in my mark at all times, This system reqiers the water to drop almost a half inch from my mark, the reason I like it to stay right on the mark is so my Protein skimmer operates at it maximum setting. Ill give it a couple of months to see if I need to upgrade or not. Joe
  • works exactly as it should with very easy configuration By Kevin on 8/23/2014

    I recently bought this auto top off for my biocube 29 hqi it works perfect. it took me less than ten minutes to install and the sensor is small enough to be placed anywhere. it seems like the other day something splashed on the high water alarm so its alarm went off but after wiping it dry everything went back to normal. works so simply I bought a second for my other aquarium.
  • Nice Product if you mate it with the right pump By Rafik on 7/24/2014

    I must say that i have had mixed feelings since i got this product. At first, i tried connecting it to Maxi-jet 1200pump which was too powerful and the water ended up getting to the max level and the alarm would sound. On contacting hydor, they reocommended a pump of max 30 gph and one that would do the job in 10 minutes before the ATO turns the pump off. I ended up getting a hydor seltz 185gph with a flow control knob (also because the ATO only accepts 2 prong plugs).

    I have been using it in my 40g long (48"), the sensor is very reliable and not interrupted by salt creep or snails or anything. However, there is about ~ 0.6 "between the min and max level so the ATO ends up kicking in every 3-4 days (without any drastic effect on salinity.
    That is the only could be considered a disadvantage really.

    From what i think, this sensor would be perfectly suited or better suited for a tall as opposed to a long tank if you know what i mean.
  • Nice simple system that needs a few tweaks to be perfect By Greg on 5/9/2014

    I think this is mentioned in a couple other places, but one key thing to getting this ATO dialed in is to either pick a pump that will fill the water from the min level to the max in 25 seconds to 10 minutes. Otherwise if you'll be constantly triggering the alarm function on this ATO (for either overfilling or it think the ATO reservoir is empty). Once you have the return pump dialed it is a great ATO.

    The setup that I have that is working nicely is using an Aqua Lifter with a valve from one of my drip acclimators to limit the flow of the pump. This way I can top-off the return section in my 13.5 gallon AIO in around 1-2 minutes. This prevents it from filling to fast; overfilling and thus tripping the alarm.
  • Great product By Swisher on 4/27/2014

    Really nice ATO system. The sensors keep the water level spot on in my sump.
  • good product By mnight on 4/27/2014

    This is a good auto top off system, with a few tweaks it works perfect.first of all the margin between the max level sensor and alarm sensor is very small about 8mm. The system tends to overfill setting off the alarm constantly. To correct this problem install a syphon break in your return line, which is simply a pin hole in the return line in your top off water reservoir above the water line. Water will squirt out off the hole so it must be in your reservoir. This will force air into the line breaking the syphon that's created once the pump shuts off. You can also add a ball valve to the line to slow the flow coming from your pump. I recommend using a small hose around 1/4 in for your return. With these small tweaks you will never have any problems with this system.
  • good product By mnight on 4/26/2014

    This is a good auto top off system with a little tweaking you should not have any problems.the system tends to overfill and make the alarm sound, by adding a syphon break which is simply a pin hole in the return line above the waterline in your top off container. This will force air into the line and breaks the syphon.this will keep the pump from over filling.also I found its best to use 1/4 hose or something close to it. You can aalso add a ball valve to the return line to slow the flow down a little. With these small tips its a great controller.
  • Have to power cycle often By Jordan on 4/20/2014

    More often than not, the product works fine. However, I have been awoken in the middle of the night to its alarm several times because the water got too low and for some reason it did not turn on the pump to top off. A power cycle always fixes the issue. Also, it has overfilled several times. Not overfilled to the point of a problem, but overfilled enough to make it audibly alarm for several minutes.
  • EXCELLENT By Z28 on 3/31/2014


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