Hydor Smart Level Controller Auto Top Off

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  • Hydor Smart Level Controller

Hydor Smart Level Controller Auto Top Off

80% Recommend this to a friend (24 of 30)

SKU: 207981

reg. $94.99

Special Price: $80.74

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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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Product Questions

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.
Question by: Kelley on Apr 8, 2014 5:40:00 AM
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.
Answer by: Bulk Reef Supply on Apr 8, 2014 5:40:00 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?
Question by: Joe on Apr 22, 2014 11:10:00 AM
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.
Answer by: Bulk Reef Supply on Apr 22, 2014 11:10:00 AM
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.
Question by: David on Apr 16, 2014 6:34:00 PM
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).
Answer by: Bulk Reef Supply on Apr 16, 2014 6:34:00 PM
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.

Question by: Chris on Jun 27, 2014 11:03:00 AM
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:
Answer by: Bulk Reef Supply on Jun 27, 2014 11:03:00 AM

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



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  • Would not recommend it or buy anthr By Whitedog on 11/16/2015

    Screwed with it for days and still just about any action in the sump including it topping off sets off that stupid alarm. It's to the point I just ignore it now. One day it will be real and I'll get screwed.
  • Worth the Money By DAVID on 9/10/2015

    The only thing that I would buy with this ATO is a ball value to adjust the water flow so the it will not fill the sump too much when the levels go low. Doing thing this works great. I have see someone complain about the calcium deposit on the sensor after 8 months. I am going on 9 months now. It must be safe to amuse that they DON"T clean their equipment with Tunze Citric Acid which can be purchased on BRS. I try to clean all the equipment every 3 months.
  • alarmed failure with the pump in the on position By Charles on 8/31/2015

    after running this for 8 months, it failed in the on position flooding the sump and the resulting room. i found that the max level sensor was covered in calcium deposits. i removed it and reset the water level. it cycled and stopped correctly. on the first natural cycle after the cleaning it failed the same way flooding the room again.

    the alarm sounded both times and the pump was not turned off by the controller.

    i have opened a warranty case with hydor that has not been responded to yet. Prior to this failure i would have rated this as a 4 out of 5 star item. the false alarms from this unit are numerous. now that it is having real alarms and not stopping the pump, i have real concerns.

  • Do not do it By Joesreeftank on 8/23/2015

    Mine was less than one year old and failed on, Yes good thing My fish room has a shower liner that contained the 5 to 10 gal of water.. but what realy bothers me is no phone number to call!! you need to communicate via email, very frustrating. I still have not been able to take care of this issue. I went ahead and purchased the Tunze... Much better item it will really keep your water at the level you set it.. The Hydor had to drop i a
    half inch to kick the pump on and in my sump that's about 1.5 gals
  • Works great. By Jonathan on 7/25/2015

    I've had it for about 6mo and it works great. I had to use a 100gph pump.
  • Good could be Great By Steve on 7/1/2015

    Super easy no moving parts. Only draw back suggestion is make the "space between the High water sensor and the alarm sensor bigger. It is too easy to trigger an alarm.
  • A great ato system, works well By Laurie on 5/18/2015

    I have this ato in my Red Sea max 250 rear sump, the level is critical for the protein skimmer to work properly and it keeps it spot on. Because the Hydor use's conductivity to operate it's very important to keep the sensor clean for proper operation as I found out when I had a low water alarm after approximately 2 weeks from the original new set up. But like any ATO system it has to be kept clean, so every water change I'll clean the sensor with RO water. It's called maintenance and not a huge concern. Glad I went with the Hydor ato.
  • Love it! By Steve K on 4/15/2015

    I have wanted an auto top off for a long while. I purchased the Hydor because there are no moving parts to jam. It was easy to set and forget!
  • 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.

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