jQuery UI Accordion - Default functionality

Hydor Smart Level Controller Auto Top Off

Click on image to zoom
View full size image

More Views

  • Hydor Smart Level Controller

Hydor Smart Level Controller Auto Top Off

86% Recommend this to a friend (19 of 22)

SKU: 207981
Please wait...
Orders over
Ship Free
Reward points What's this?
Ships Monday

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).

Related Products

Ask a question

Please Sign up or Login to ask a question

Previously Asked Questions

  • by Kelley on April 8, 2014, @5:40 AM

    Could you recommend a pump or two that are known to work with this ATO without filling past the maximum level? This seems to be a known problem with this system.

    "Maximum Pump Power: 50W" doesn't tell me much.

    Bulk Reef Supply Hi Kelley,
    The auto top off system cuts off power to the pump as soon as the max level is reached. If the pump is off, it can't continue to pump. Any water that continues to travel to the sump at that point likely is either because the system was setup incorrectly and a siphon has been created (which would be bad, as it would continue to flow and potentially overflow) or its just the remaining water in the tube draining via gravity. The later shouldn't be an issue unless one is using really wide tubing or a really long length of it (but largely the pump selection wouldn't make a difference there). The most common pump folks use is the aqualifter pump which uses small 1/4" tubing so any water that continued to drain from there would be pretty minimal and it comes in well under the 50w maximum of the top off itself.

    Do you find this question helpful?  Yes   No

  • by Joe on April 22, 2014, @11:10 AM

    Is it possible to mount the probe on a bias so that the distance between high water/low water sections of the probe is reduced? Say on a 45 degree angle? Would that help ATO's on smaller gallon sized systems not have such a significant top off each time.....thus helping maintain salinity more consistent?

    Bulk Reef Supply Hi Joe,
    I haven't ever tried it but it wouldn't be my first choice (might be some unexpected consequences). Really the probes are pretty close together so this isn't likely to be an issue on the vast majority of tanks. Really whether its a nano tank doesn't change much, how much water you need to add to go between the low level probe and high level probe is almost entirely dictated by the surface area of the return chamber of your sump. If its a 25" x 30" chamber its going to take a lot more water to raise the water level by 1/4" then if its a 2" x 2" chamber. Its unlikely that most nano tanks would have a chamber with a really large surface area for the return pump, so its unlikely to be an issue for the vast majority of folks.

    Do you find this question helpful?  Yes   No

  • by Chris on June 27, 2014, @11:03 AM

    I was thinking of getting this ATO and was wondering what pump you would recommend. There will be very little head pressure on the pump since I have room to put the top off resevoir right next to my sump.


    Bulk Reef Supply Hi Chris,
    In very low head pressure applications the Aqua Lifter is the most popular choice by far. You can find it at the link below:

    Do you find this question helpful?  Yes   No

  • by David on April 16, 2014, @6:34 PM

    I recently purchased on of these along with a few other things just last week. Well I hooked up this system today and went to work. Later on I get a call from my wife telling me that my sump is overflowing with water and the alarm is going off. Now luckily there was no wildlife in my tank or I would have been real upset. Also, that my wife was home. I'm using the Cobalt MJ1200 pump that was recommended by you guys. My question is, why would the pump continue if it's supposed to shut off once it reaches critical. I will look into my set-up to make sure I didn't do anything wrong. But I followed the guy in the video.

    Bulk Reef Supply Hi David,
    It depends on how you set things up but 99% of the time on a new setup its because you set your system up to dose from a area of higher water to an area of lower water and you created a siphon, so the system turned off but since you created a siphon water continued to travel to the sump. The fact that the alarm went off indicates that the ATO system itself was likely operating correctly. You need to make sure that your ATO system pumps water to somewhere higher then the water level in the ATO container. If you have a tall ATO container or an unusual setup where the container is physically higher then the sump, then you will want to run the ATO water to the tank itself (or overflow box).

    Do you find this question helpful?  Yes   No

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



Items 1 to 12 of 22 total

  1. 1
  2. /
  3. 2
  • Great ATO By James on 3/23/2015

    I decided to go with this one over making my own and i am very happy with it. The only thing to be aware of is that when you turn it on after doing maintenance it will still give high water alarm for a few seconds to a minute as the temp of the sensor normalizes so that it accurately senses water level is lower than the alarm level. Give it time and alarm will stop.
    There is a switch on the unit so you can turn it off when needed with out having to unplug it.
    Also I use it with a dosing pump so it fills slow and have the sensor in my return chamber so it is only about a 1/4 gallon between the two min/max sensors to help with stablitiy.
  • Not the best auto-top-off on the market. By Luke on 3/10/2015

    The hydor smart level controller is something I bought out of necessity when my Tunze ATO stopped functioning properly. I don't particularly like Hydor because most of their products seem big and clunky like the Koralia Wave Maker for example.
    One major design flaw I noticed with this ATO is that the power cord on water level sensor is positioned horizontally. The problem with this is that when you run the wire up and over your sump it has a tendency to pivot the sensor 90 degrees so that all three water sensors are facing down, thus becoming ineffective at measuring the waters level. I had to zip-tie the chord to the sump using a stick-on bracket so the sensor wouldn't pivot.
    The second problem I had with this ATO, which many others have, is the alarm function. While it is nice to have an alarm to warn you when the sump is too full, I thought it was rather annoying whenever I did a water change or other maintenance. Usually when I do a water change I am not exact on replacing the water volume, usually 1/2 to 1/4 of a gallon off. When I filled the tank with this much extra water my ATO would alarm me for hours until that much water evaporated. I would end up unplugging the ATO until the water was below the sensor.
    Overall I think Hydor could make some easy adjustments to improve this product.
  • Love it - hope this one lasts By bigtang1 on 3/8/2015

    Does a great job My only issue is that this is my second one I bought one as soon as they were released and it failed recently I bought another one but if this one goes I'll move on
  • Simple and efective By James on 2/19/2015

    I have mine connected to a 55 gal. reef tank. I have a canister filter so the sensor is in the tank. I adjusted water flow from the top up tank with a ball valve so as to give the sensor more time to detect temperature change. Right now the pump turns off when the water reaches half way up the max level sensor there by giving me added distance from the alarm sensor so as not to cause a false alarm from wave action.
  • Love it By David on 2/10/2015

    An accurate ATO. What I like about this product is that if it is left in the "on" position for more than a couple of minutes it will beep. A great fail-safe addition!
  • Great product By Eric on 2/8/2015

    This is my first ATO after using an unreliable gravity drip system for the past 10 years. Easy to set up and operate. Love not having to worry about float switches sticking. I am using the Tom Aqua Lifter pump which provides the perfect flow rate and quiet operation. The only complaint I have is that the volume of water between the low and high point sensors is on the high side in my current un-baffled sump. My new sump, that is under construction, has a smaller return pump chamber and will fluctuate volume faster thus keeping salinity more constant.
  • Works like as advertised. No problems. By Ron on 1/27/2015

    Using the Hydor to top-off my sump from a small bucket that is sourced from my ro/di system, Using a float valve to control the ro/di input to the bucket adjacent to the sump
  • 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.

Write Your Own Review

You're reviewing: Hydor Smart Level Controller Auto Top Off