Return pump auto shut off?

[Europa13]

Are there any return pumps available that have an automatic shut off when they suck air? My sump would run dry with 2 gallons of evaporation and I was thinking a return pump like that would be a good safety mechanism, although I do have an auto top off.

What would happen if a Mag 9.5 ran dry? Would it shut itself off or trip the GFCI? Would it keep going until it burned itself out? I realize it would damage the pump, I'm more concerned about the effects on the DT and sump.

Thanks.

 

[just dave]

Blueline and Tunze have pump shut-off set-ups that can be added to your system. The work like auto top-offs but in reverse.

 

[Europa13]

Would I have to replace the pump or is this something that can be added to the Mag 9.5?

Do you have a link for the Tunze?

Thanks

 

[just dave]

The Tunze unit is called a Water Level Alarm (7607/2) and the Blueline unit is called a Pump Saver. You just plug you pump(s) into them. The Blueline unit as well as the Tunze unit can be had from Champion Lighting.

 

[LobsterOfJustice]

You can also run a float valve in reverse mode, like the one on autotopoff.com.

http://www.autotopoff.com/products/SS1/index.htm

 

[Twz]

<a href=showthread.php?s=&postid=12503242#post12503242 target=_blank>Originally posted</a> by LobsterOfJustice
You can also run a float valve in reverse mode, like the one on autotopoff.com.

http://www.autotopoff.com/products/SS1/index.htm

Beat me to it =D

 

[just dave]

You have to know what the load ratting is for the float switches as they may not handle the higher loads of some return pumps .
The Blueline unit has a 3 amp max cap and the Tunze unit has a 7.8 amp max cap.

 

[landlord]

The autotopoff set-up is run through a relay so the load shouldn't be an issue, I think.

 

[SeanT]

I toyed with the float switch idea a few years ago.
The one problem I had, and couldn't figure out how to overcome, was if the float switch went too low the pump would shut off (good thing), THEN as the water from the display would come back down, as it does float rises pump on (bad thing)...water pushed out pump off etc. etc.

Anyone know a way around this vicious little circle?

 

[LobsterOfJustice]

Oh boy, didn't think of that. You would need to set up some kind of dual switch setup where both switches need to be deactivated in order to shut the pump off and both switches need to be activated to turn it back on. The link I posted earlier has dual float switch setups, but you might need to wire it differently to work as I mentioned.

 

[SeanT]

I was also thinking of a setup my buddy Jim had.
If he had a power failure, he had it setup to where he had to manually turn the return pump back on so as not to cause any issues.

I wonder if something could be wired into the float switch to where if the circuit were opened, stopping the flow of electricity, that it would trip a breaker of some sort that could only be reset manually preventing what I described above.

 

[just dave]

The Pump Saver, which is just like their Auto Top-off (AT-1)but reversed, uses an air pressure switch instead of a float switch and it is not as sensitive to level changes which helps with pump "bounce." It's also what makes their AT-1 not ideally suited for every application. I have never used the Pump Saver but I do use a few of the AT-1s and have never had one fail to date.

 

[SeanT]

Hey Dave...I am not referring to the bounce of the float switch.

Your sump runs about half full right?
When you kill your return pump it fills up.
If the water in your SYSTEM is low, the water in your DISPLAY is still where it always is...but if the SYSTEMS volume is low the float switch will shut the pump off.
Which causes the water from the DISPLAY to go back to the sump turning the pump back on by raising the water level...and this would just continue unless they are offering something that I didn't see.

 

[just dave]

I understood, that's called pump bounce around here. The same thing can happen , for different reasons ,with a ATO pump if the switch range is too sensitive. Each situation causes the pump to go on and off until the appropriate levels are reach. The Pump Saver may have enough range to prevent that. The Tunze utilizes three separate float switches. I've not looked into it to see what they are set to but you may want to investigate as it may prevent what you are referring to. I use a check valve to prevent the tank from draining down past the returns to prevent excess splashing on restarts. It would also prevent the situation you are referring to.

 

[just dave]

OOPS.

 

[jeffhaag]

Not that I recommend it, but over the past 6 years of running my 90gal tank, my ATO FUBARed twice and my Mag 9.5 ran dry. One of the times it FUBARed I was on vacation and the pump ran dry for several days sucking just splash and air. To this day, the pump still runs fine although I just retired it to saltwater mixing with the setup of my new tank.