Neptune Aquatics

Float switch failure

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sjbro

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For a few years, my ATO system consists of 2 float switches hooked to ReefKeeper that controls a small pump. I have the float switches on a vertical bracket with one being active and the other one being the emergency shut off. They are connected in parallel to the same port on RK, the main/active switch is in the water; it is open when the water level is low and closed when the water level is topped off. The emergency switch is out of water & open unless the water level goes over the main switch, then it closes once the water reaches its level.

Until now, this setup worked without problems. When the active switch would get stuck because of a snail or dirt, the water will raise a few more inches nd activate the emergency switch.

But on Thu, I noticed a different type of failure: the active switch didn't open when the water level got low. So it didn't activate the ATO pump. I found the issue when I noticed the air sucking noise and bubbles from return pump.

I replaced the switch with a spare one and everything works again. My ohm-meter said that the bad switch is working again 30 min or so after I removed it. Immediately after I removed it, it would not open the circuit. About 30 min later when I checked it gain, it worked properly. But I don't trust it, so it went to garbage.

I am thinking to change my config to use 3 switches:
- 2 active ones, on the same level, that each could trigger the ATO pump when the water level is low, but it takes for both of them to close to turn off the ATO.
- 1 emergency switch, above the first 2, to turn off the ATO pump if any of the lower switches fails.

How do you guys configure the ATO switches? How many do you use?
 
Even though I have an apex, I'm using my JBJ ATO with 2 floatswitches that I got before the apex.

I have it on Mode A.

1 switch turns on when the water level drops and pumps water into my sump

1 switch, I took out the float and flipped it upside down. When the switch is activated, it shuts off the pump. This is my secondary switch that ensures that my sump does not get flooded with RO water.
 
I run a 4 system float switch system in my sump but a single float switch for ATO....I too have an Apex and use the float switch to dis-allow or allow the OSC programming to fill up my sump from my ATO container.

The OSC programming is an oscillating program meaning you get an OFF/ON/OFF style programming and I have mine set like this: (OSC 016:00/001:18/042:42 Then ON) which stays OFF until 16 min after the hour before it turns ON and will run my ATO pump for 1 min and 18 sec and the turn OFF for another 42 min and 42 sec until it starts again at the top of the hour.....I programmed my ATO pump this way so my ATO pump could never get stuck in the ON position if my float switch got stuck or failed in the closed position and mess up my salinity or overflow my sump, granted I have many other fail safes to not allow this to happen to my ATO pump.

I am not sure on the type of programming you can do on a ReefKeepre, but in the Apex world it is NOT ADVISED to ever have a pump turn ON when a float switch is OPEN as if the BOB (break out box) on the Apex ever gets disconnected it shows as open and you wouldn't want that if the BOB get disconnected it turns on the ATO pump and you get bad things happen.....
 
The two risks are backwards IMO.

Risk 1 - not enough top off - worst case is you will get some bubbles in tank before you notice and fix things
Risk 2 - too much top off - worst case is you kill your livestock and flood your house

Make sure you have much more protection for Risk 2.

I would let the pump run until X number of seconds after any of the switches indicate high water. This prevents the water from sitting right at the on/off point and toggling a million times per day with each tiny wave. X depends on the pump top off speed.

!!As mentioned earlier - make sure you understand failure modes with your controller and your choice of configuration, i.e. does a loose wire make bubbles, or flood your house.
 
Thanks, guys. I haven't properly used the terms open & close in my post above. My switches are in the open circuit position when the water is topped off. So when the water goes down the switch actually closes the circuit to activate the pump. Which means the pump won't start if a wire gets cut or loose.

I agree that risk 2 is much worse than risk 1 - and I am covered for it. I do have the second switch to stop the ATO pump. And yes, there is a timer on the RK for the ATO pump.

I was hoping I can also find a solution for risk 1. My interest to address risk 1 lies in the fact that there are longer periods of time when I am not around my house & tank, so there will be nobody ready to fix the issue. I got lucky that last week when it happened I was at home. Next time I might not be that lucky - if it happens when I'm away, my only choice will be to instruct my family to shut down the return pump. They won't know how to replace the float switch :(.

That is why I was thinking to use 2 float switches on the same level to alienate the risk 1. Then if one switch doesn't turn on the ATO pump, the other one will do it. One thing I don't like about this solution is that I won't know if both switches work. If one fails, the system still works, there is no indication that one of the switches is gone. So I would need to periodically inspect them for failures.

There is the option of adding a 3rd switch to a lower position, so have 3 float switches at different levels. Then the middle one remains the main switch & where the water tops off in regular conditions.
If the middle switch gets stuck in CLOSED position, the top switch will shut down the pump when the ATO pushes the water up to its level.
if the middle switch gets stuck in OPEN position, the bottom switch will be responsible to turn on the ATO pump when the water level drops below it.

This solution would give me at least some visual clues when the main switch is not working. But it means to keep the low switch underwater all the time; that is prone to the switch getting stuck with dirt, coraline algae or other worms.
 
You could also just use 4 switches. Two parallel sets, each with 2 switches in series.
Same as you had, but make two sets, and connect the end points of each set together.
Yearly maintenance could be to check the switches.

Ideally, you do it in both software + hardware.
Software reads a normal float switch and controls ATO.
Emails if something is strange.
A higher float switch is on a separate relay, as a fail-safe, in case software hangs.
 
Yes, that might work. Thanks. I would need to buy at least one more adapter for RK. The one I have right now only supports 2 switches.
 
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