How to Wire a Tunze Nano ATO
Written by Dan
The odds are if you are reading this article you are like me and purchased the Tunze Nano Auto Top Off ATO. You proceeded to open the box and think WTF and go to google to figure out how to connect the wires. Yea me too!
If you have not yet purchased an ATO I highly recommend the Tunze Nano ATO 5152. I do really love this ATO and would most certainly buy another if I ever needed another ATO.
I have created this article in hopes that I can help others who may have the same questions I did when I first got mine.
In all truth, connecting all the wires is really easy…. Once you understand how they all connect.
First to the heart of the matter and then stick around and lets talk about a few other things concerning this ATO.
Wire the Tunze Nano ATO
To connect the pump to the controller you need to use the wires at the end of the white cord sticking out of the pump to the two plastic squeeze plugs which are connected to the controller box.
The part that confused me was which wire goes in which connector. As shown in the picture below place the blue wire into the the black wire with the white line and the brown wire into the solid black line.
To connect the wires grab one of the connectors between your finger and thumb and squeeze to push the trigger in. This opens the hole at the end of the connector. Slide the appropriate wire into this hole and release the trigger. This closes the grip down on the wire holding it in place.
When inserting the wire in you should push it far enough in so that the bare wire is not visible, but not so far that the gripping mechanism is closing on the plastic shell and not the metal wire.
That is the most difficult part of setting this ATO up but I will admit was a real head scratcher for me when I opened the box and flipped through the instructions. I was afraid to mis-wire it and burn up the controller.
To complete installation; place the float inside your sump or tank, at the proper water height you want maintained. Use the magnet on the outside of the sump/tank to hold it in place.
Drop the pump into a bucket of water, plug in the controller and boom all done. If the water level is so low that the float is at its lowest possible point, the pump kicks in. Once enough water is pumped in to raise the float, the water cuts off.
What size tank is the Tunze Nano rated for?
This Auto Top Off, is rated for up to 55 gallons.
If you are using it on a larger tank say 40 – 55 gallons rather than 20 – 30, you may notice that the pump cuts off before the water actually reaches the waterline you have set the float at. This is due to a built in safety feature in the unit.
The pump will cut off if it has run for 2 minutes straight. This is to avoid overflowing a 20 gallon tank for example. If something was wrong with the float and it didn’t raise back up you would not want the pump going until it completely drained your water bucket.
So it cuts off at two minutes or approximately 0.9 gallons pumped. If you have a larger tank that evaporates more than 0.9 gallons before the ATO kicks on this does not help. Inside the control box is a jumper that allows you to change this from a 2 minute timer to a 4 minute timer.
At 4 minutes the pump will pump about 1.75 gallons before cutting off.
How do we adjust the safety timer?
First off we need to open the control box. The control box is the small black box about 1.5 inch x 1.5 inch in size. Using your fingernails or a small flat head screw driver, etc; push in the safety latches on the sides of the unit allowing the top and bottom of the control box to separate.
Inside the box you will see a small green computer board with all the wires connected to it. If you are holding so the wires point up, there is a jumper in the bottom left corner of the board. A jumper is a small connector that somewhat resembles a a fuse in shape. It is plastic on the outside but has metal connectors inside. It slides overtop of two metal pins connecting them together.
The name jumper comes from the fact that it lets electricity jump from one pin to the other if it connects them.
Slide the jumper off the two pins and slide it back down over just one of them leaving the other uncovered. This is depicted in the picture below. Make sure to not bend the small metal pins while doing this.
If this is read by Tunze, I ask that you give us an actual switch accessible w/out having to pop open the case in future models.
Can this handle bigger tanks if it is measuring the sump?
I actually use it on my 40 gallon sump attached to my 180 gallon reef. Having the float in my 40 gallon sump works, if I put it in the 180g tank it wouldn’t.
This works because it is measuring water evaporation in the 40 gallon not the 180. Even though water evaporates from the 180 too, it simply cuts on more often.
If you need an ATO to handle more than a 55 gallon tank check out the Tunze ATO 5155.
What is your experience with this ATO?
What can I use to hold my water?
Honestly you can use anything the pump fits in. Since the pump is small and cylindrical. About 1.5 inch diameter and 3 inch tall it fits in most containers. I like to use the standard 5 gallon jugs that are common in the hobby. You can simply drop the pump into the bottom of one and swap out the jug for a full one when it goes empty.
Beware the Water Siphon!
One thing you should be aware of with any ATO is the possibility of creating a siphon between your resinous jug and your tank. By this I mean a siphon similar to what you create when draining your tank or using a gravel vacuum to clean the bottom of your tanks.
The same way those drain water from the tank your ATO hose can too. To avoid this make sure the exit end of the hose feeding water from your ATO to the tank is mounted so it is always above water. If it is above water than it cant suck in water and create a siphon that would drain your tank into the reservoir.
The other siphon issue is when your reservoir is mounted above the outlet of the water hose. This is a big no no since this creates a siphon in the opposite direction that would drain the reservoir into the sump/tank.
I hope this article has been helpful to you. I really like my Tunze Nano ATO 5152. If you are looking to setup an ATO or change out an existing one I am a fan and would recommend this one to anyone. You can check the price of this ATO on Amazon by clicking here or find out more about ATOs and check out our article on the most popular ATO systems by clicking here.