Smart Level Controller Auto Top Off - Hydor

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  • Hydor Smart Level Controller

Smart Level Controller Auto Top Off - Hydor

74% Recommend this to a friend (25 of 34)

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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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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  • Meh. It's a maybe. By Fred on 1/21/2016

    Mine failed after 6 months. Had to fight with Hydor through email to get them to send me a replacement. After a couple weeks the replacement came, I used it for a few weeks then sold it on eBay, as soon as I got the Tunze unit installed. Like most people say, buy the right piece of equipment first. This may work for you for a little while, or it may fail. The sensor can either be too sensitive, have too much leeway, or be just right, depending on where it is positioned in the sump, the size of your sump/chamber and how the sump is configured. No adjustments. Do yourself a favor, save up a few bucks and buy a known good product, the Tunze.
  • Decent By HannSolo on 12/20/2015

    #1 You absolutely need to remember to drill a hole in your tube to break the siphon.

    #2 The delayed reaction on the sensor requires an appropriatly sized pump or youll need to invest in a Y fitting and a ball valve to control how much topoff water is pumped into the sump.

    #3 I would recommend testing the system with regular saltwater for the topoff and removing water untill it kicks on so you can see it in action.

    #4 Whoever decided some sticky tape would work well in your wet sump to keep the cord horizontal must be retarded. You'll need to invest in some extra magnets to keep the sensor from pivoting
  • not a reliable means of top off in a sump By jake on 12/14/2015

    This product does not work well. Simply put there is too much lag time in between the sensor shutting off the pump and by the time it does shut off it over fills to the point of constantly setting off the alarm. Even taking it out of the sump on my dt setting it up on my 30 gal qt tank it would let about 3 gallons of water evaporate before even turning on and refilling. At 3 gallons my salinity rose significantly ad well as my copper ppm which is a no go.. if they could fix the lag time in response to the sensor shutting off the pump it would be a great product. I would not recommend this product to a fellow reef tank owner.
  • Stopped Working after 2 weeks By Kevin on 12/9/2015

    It worked fine for the first week. After 2 weeks it stopped working. My water got low. I had thought that maybe there was in issue with the alarm and it stopped the pump. So, I filled it to the proper height, checked the pump was working, and restarted the unit. Still did not turn on.

    Checked the sensor in my sump. Still clean and did not move. Don't get this ATO. I got a Tunze instead and it's working great.
  • 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!

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