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Aquahub's Auto Top-It-Off kit

Rating: 5 votes, 4.80 average.
Years ago, I got a kit from for my reef. I never did update my float switch system to his safer relay approach. Here's what I had for the past 8 years or more:

With the new set up, I've tried to avoid holding anything back and went "all in" so to speak. So I pulled out the kit and noticed I needed some goodies. I called up Patrick at Aquahub and asked if he could ship me the missing pieces. He wondered where I got that original kit from since it was removed from production years ago. Here's what the kit looks like today.

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He shipped me the relay plug in bar and a couple of plastic pieces that seal the top of the wires from saltwater damage.

So I got busy Sunday night, wiring up this ultra safe system. The way it works: You have two float switches wired in series, which are powered with a 12v DC power supply. When the switches are down, a relay opens the flow to a 110v power cord to supply power a pump that can push top off water from a reservoir into the sump. As the water level rises, the float rises and cuts power to the relay, which stops power to the 110v cord shutting off the feed pump. If one float fails, the second one is a back up to make sure power is cut to the feed pump.

Installing the floats was easy. My sump had two float switch brackets glued in and pre-drilled. Threading the cord up through the hole, I placed the switch in position, and screwed the nut in place to keep it secure. Then I screwed the plastic round tube to the top, filled it up with silicone and pressed 1/2 tubing down over the plastic piece. This creates a dry zone even if the water level rises in the sump. For safety, I went ahead and filled the tops with silicone as well.

Using the instructions on the website, I followed the images and directions to wire the switches first, and test it. Then the 8' extension cord was wired in and the system was tested again.

The tools were simple - most people have these on hand.

The one thing I did differently was to use these little low voltage connectors. I didn't have the other kind he offers in his kits, but my substitute is fine.

After I knew everything was working, I modded the enclosure box to permit the cord to come out each end.

This is what you end up with, although cord lengths may vary based on need. The black transformer powers the relay, and the plug on the left feeds power to the outlets on the right. The black 'project' box keeps the relay assembly clean and dry.

I'm using an Aqualifter to move water from the reservoir to the sump. It needs a mere 3w, but with this kit you could use a larger pump without concern. Don't use a pump rated greater than the extension cord can handle; usually for top off we don't need a fast pump but rather just enough to get the job done quietly.

Using zip ties, I affixed the box to the center beam of my stand.

I had some cable management tubing to keep the wires tidy. Note how I keep the outlet tied up where it can stay dry.

The same tubing gathered up the fine wires from the two floats.

The two cords run to the DJ switches at the end of the tank. I can flip off either switch to turn off the ATO system whenever needed.

When the water is being topped off, this tall tube keeps the water from splashing and avoids siphoning out too much water if the reservoir is full.

It's working perfectly, and I'm very happy about that. Top off is pretty important, and not having to lug water to the fishroom any longer is wonderful. Having a safe top off system installed to replace evaporation is key to making this hobby more enjoyable.

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Updated 02-27-2011 at 07:08 PM by melev

Tags: aquahub, ato
Electrical , ‎ DIY projects


  1. gr8t1dini's Avatar
    I have the same kit. I didn't use it with my 110 since I decided to get the tsunami ATO. I works very well. i'm going to use the Aquahub in my frag/QT tank. What holds the tube in place?
  2. evoracer's Avatar
    Nice clean install. Looks like a good foolproof kit. And nice MAX vendor schwag-bag flashligh as well! I love that thing!
  3. melev's Avatar
    The vertical tube is on an acrylic riser plate.

  4. Turbosek's Avatar
    What happens if either of the sump level float switches fail? Is there some sort of system that prevents the sump from overflowing, or running dry? I am sure you could go many days before the sump would run dry, but overflowing might be another story. Does the lifter pump shut off if the high level float switch fails?

    Similar to my ATO reservoirs, I plumbed a bulkhead at the top few inches of my sump...and have it plumbed to my waste drain. Worst that will happen is wasted water going down the flooding. Your fish room is pretty set up for floods thought...probably would be no big deal.

    Great pictures and details.

    One more thing. What is your opinion on gravity feed ATO with manual floats, versus the electric switches and pump? I use gravity. I have my ATO container plumbed to 2 manual float valves in the case one fails, the other one keeps things going fine. I am just wondering if there is a down side to this setup.

  5. melev's Avatar
    Both switches would have to fail and then the aqualifter would continue to top off. Since it is such a slow pump, odds are I'd notice the problem. I ran the last float switch for over eight years with zero failure, so I don't anticipate any issues from having two of them now.

    A third switch could be installed in the reservoir to turn off the pump if that container ran low, but that's unnecessary for this application.

    Having a hole near the top of my sump to handle excess water isn't what I want. I prefer to have all the capacity, even if it overflows some day. It shouldn't. My last one never did, not once.

    Gravity fed systems are even more reliable. You do need to limit how much water is in the reservoir to avoid altering salinity too greatly. Can you post a picture of your dual floats? So you have two different feed lines both going to the sump?
  6. oaksenov's Avatar
    Hey Mark, What do you think pros and cons of using separate ATO like this one vs. using controllers capability do the same thing with floats?
  7. melev's Avatar
    For me, the difference is that everything is at a single point of failure. I do like to divide up the various tasks my tank needs across a few items. It may be excessive but it hasn't failed me yet.