View Full Version : ATO for 40 breeder display tank

03/20/2017, 08:48 AM
I have a 40 breeder reef tank with no sump. I need an ATO and have two questions below.

1. Do you recommend the nano or regular ATO for a 40 breeder?

2. Since I have no sump I would have to install it directly into my display tank. Would this be ok? How much room does it take up? Does anyone have a picture of one installed on their tank?


03/20/2017, 10:01 AM
For this size tank you could use either.

The 3155 has more safety, it is more precise, however it has 2 sensors so their is more in the tank and the water level will run about 1.25" below the trim. It can also be finicky on smaller tanks because it deliberately overfills for 5 seconds, this is only about a tablespoon of water, but it can result in an overfill alarm on a set up under 40 gallons, the solution is to turn down the pump speed and maximize the distance between the sensors.

The 3152 has only a timer as its safety, the water level will be about .75" below the trim, it has only one in tank sensor so it takes up less room. You also will need to be sure to set the safety timer to 3 minutes, the default is 1 min 48 sec and rated for up to 25 gallons (3min is for up to 55).

03/20/2017, 10:35 AM
Thanks for the reply. Just to clarify my tank has the normal black trim around it. Prob an inch or so high. When you say .75 below the trim do you mean below the bottom of the black trim or from the top of the trim/tank?

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03/20/2017, 10:59 AM
Below the bottom of the trim, European tanks don't have this trim and it prevents the magnet from being moved up higher.