Hydor Smart Level Controller, Automatic Top Off, ATO

I bought this for my 90 gallon saltwater tank and it works great.

First let me address some of the negative reviews you will or have read:

Some complained that a standard two pole plug does not fit because the unit does not support the larger pole. The unit I received did NOT have this issue, it had a normal connection that will accept any two pole plug, so they must have fixed this issue.

Many complain about a delay in turning off the pump. It's true, it takes 30-60 sec. (maybe a little more, I didn't time it) for the pump to turn off, but this is normal for temperature differential technology. The probe has to be out of the water for a bit before there is a noticeable temperature change. The key is to use an appropriately sized pump, such as the TOM Aqua Lifter (which is what I use) or a dosing pump. My pump can easily run for several minutes (like 10 or 15) before the water level reaches the next sensor.

I have also read some reviews that claim the system would continuously fill and over flow their sump, one even mentioned it continued to fill after they unplugged the pump. This is NOT a problem with the Hydor Smart Level Control or the pump, it's a design issue. You simple have to place the end of your fill hose higher than your top off water, otherwise it will siphon water even with the pump off. I placed the sensor in my sump and the fill hose in my display overflow which eliminates this possibility.

So here's my assessment:

This is a great ATO.

It doesn't take up much space.

It doesn't use mechanical float switches which are prone to failure due to salt creep or other foreign obstructions.

It's well build, water resistant, and easy to mount in your cabinet.

It has MAGNETIC suction cup mount for the sensor, and includes cable fasteners to avoid pulling the cable and turning/twisting the sensor (use them).

It's reasonably priced.

Don't let the negative reviews detour you. Get the right pump; It only has to trickle in (It's okay if it takes 30 min. to add a 1/2 gallon of water, it's just a top off); and make sure the top of your water source is lower that the end of your fill hose.

Enjoy.

I just have to comment regarding Hydor's customer service. I use two of these units, one on a 65 gallon frag system, the other on a 180 gallon full blown SPS reef. These work flawlessly, but sometimes you get a faulty unit. This can happen in any industry. I recently had one of my units go out after 8 months of use. I was getting a high water alarm no matter what level the water was at. I contacted Hydor via their email address, within a day they wrote me back asking for photos of the back of the unit, along with a copy of my receipt. That day I sent them the photo, and a screenshot of my Amazon order confirmation page........and guess what - I had a brand new unit at my doorstep the very next day!!! I didn't even have to ship the defective one back, they told me to just dispose of it. These units have a 24 month guarantee, and in my eyes it was honored to the fullest. I will never hesitate to buy a Hydoe product agin in the future.

First, this product requires the appropriate lifter pump rate for it, I 100% suggest you not shop around and just get the Tom's Aqua Lifter Pump rated at 3.5 gph, which typically sells for around $15 on Amazon. It mates perfectly with this ATO. You will probably not find a cheaper pump that is dependable and matches the gph this ATO needs.

Second, the directions that come with this product are horrible. The video provided is moderately helpful, but it makes an assumption that individuals using this ATO are topping off their display tank, or that they have a raised sump. This would negate most siphoning issues most of the reviewers are happening because the setup would inherently have zero siphoning issues. Many of us using this ATO are using it to topoff a sump tank that feeds the display tank and not directly into the display itself. Because of this, most of our sumps are in fact floor level or close to it and therefore you run into issues with gravity fed siphoning. In addition to getting the right pump, you have to understand the correct principles of a siphon. In this case, you DON'T want a continuous siphon to happen, which is the reason for the lifter pump. For those that have used mechanical ATO's with gravity fed topoff tanks, this is literally the opposite principal. First, you want your siphon tube from the water topoff container to be the lowest point in your topoff system. This includes the highest point in this tubing, not just the opening. So if your reservoir tube goes up, which for most of our bucket style toppoff reservoir containers, the tube goes up and out of a drilled opening, this top most part must then be lower than the topoff fill tube side. I am using a New Wave Enviro BPA free 5 gallon water jug for my reservoir and initially, I had the tube coming out of the top cap, which is very high up. In my sump which is a 20 gallon long, this was far too high because it was higher than any point in my sump. To fix this problem, I drilled a hole lower in the jug that was lower than the topoff side. Second, you want the Tom's Aqua Lifter pump to also be higher than your topoff reservoir. This is because there isn't a shut valve in it, so if a gravity fed siphon is started, there is nothing that stops it once it starts even if it is no longer receiving power from the Hydor ATO. The directions try to tell you in a generic picture about this, but doesn't give any descriptions.

So to keep it simple, raise your topoff side to include pump higher than your reservoir side tubing. This might be tough for many of us that have your sump at the same level as your topoff reservoir. I had to raise my Aqua Lifter pump using a plant stand to get it higher than the tubing coming from the water jug. This way, once the Hydor ATO senses the max level has been reached, it will shut power to the Tom's Aqua Lifter. Then, the pump is too high to maintain gravity fed siphoning. Also, keep in mind that the fill tube must also be higher than the topmost part of your reservoir feed tube. This wasn't too hard for me because I have the fill tube hanging over the top edge of the sump tank. You don't want the top off tube to be in the sump water. If you have a lower reservoir tank and a taller sump tank, this will probably be an easy setup. Tom's even sells a hanger for the Aqua Lifter pump that lets you hang it on the side of your tank near the top. But for those of us running shorter sump tanks (mine is roughly 14 inches tall), it will take some planning. Another solution, if possible, would be to raise the level of your sump tank. However, my tank was already established and plumbed accordingly, so it would have been a pain to raise it.

Once I figured out the correct siphoning, this thing has been a lifesaver. Thanks to all those previous to me that recommended the Tom's Aqua Lifter pump. I love the magnet style sensor attachment, as it works just like my powerhead. I think it is literally the same magnet system as their Hydor Koralia powerhead, so much more reliable than a suction cup. I find that once the temperature based sensor registers that the water level is below the min level sensor, it turns the ATO pump on in about 15 seconds. The Tom's pump trickles the water in my setup, it fills the return chamber of my sump back to max level in a few minutes, not too quick and not too slow. Once registered, it turns off in 15 seconds (approximately). Unless you have a bad siphoning design, this seems to be working flawlessly and I haven't had issues with overfilling. If anything, it keeps the salinity level in a very close range due to such a small fluctuation causing it to fill (if using it to top off a return side in your sump). This is great in keeping stability in your saltwater setup.

One thing I don't like is how it doesn't seem to have a secondary backup sensor, so hopefully this electrical type sensor is reliable, I will update with time if it starts to malfunction. So far, it has been running for about a month. I do like how it doesn't rely solely on a mechanical float sensor that can gunk up with salt and get stuck. Also, it takes next to no room in my sump return tank, unlike mechanical sensors and/or float valves. If you are limited on space for your ATO sensor, this is a good choice.

In all, highly recommend this ATO. All pieces seem to be of high quality and a very nice and clean design.