ATO and Sump question

[mc524]

For some reason...my single return (now have two) lost its siphon. I had calculated both situations as in:
1. If the Pump quit, the return would not overflow the sump.
2. If the return stopped, there was not enough water in the Pump section to overflow the display.

However, at that time, I was manually keeping the Pump Section topped off. I installed the ATO months ago, and up until last week, I haven't had an issue. Luckily I heard my pump sucking air. Came down and seen the water at the top of the tank.
So I'm guessing the ATO switch came on saying the Pump section was low. It continued to fill the Pump section until the 2nd switch told the pump not to turn on inside the ATO container.
My question would be...how do you overcome that sort of problem. I have considered ordering a 3rd switch to put in the display, wired in series with the ATO low water switch. Have it in the normally closed position, and then open up if the tank gets to a higher than normal level.
I haven't seen anyone having to install a switch in their display...so what is the work around for this?

BTW, this is the reason why I am looking to upgrade not only size wise, but also to a true reef tank that is drilled. Hopefully, I won't have to deal with a siphon problem.:doh: Or will I?

 

[eagle9252]

do you have HOB OF (hang on back overflow) if so do you have a pump (PH or aqua lifter) on it that sucks the air/water out? over time it will collect mirco bubbles and slow/stop the flow. and your pump will pump untill the sump is empty and DT is overflowing and then burns up.

you would not need to have a float in the DT you could put it in the HOB OF or in the drain side of the sump. if you add a chamber in the sump that the level while running is just higher so when the flow stops from the DT it will level out with the baffle and trigger the float to stop the pump.

 

[mc524]

Thanks for the reply. Not a true "HOB" as we normally see. I now have "2" 3/4" return pipes that skim the surface. I will need to post a picture to explain it more clearly. I found the design on Youtube, and works quite well. However, just like any HOB setup, if you lose siphon, big problems. It works along the same lines as a HOB for the most part.
I may do the 3rd switch and install it in the Sump. This will only be a fix for this current tank. I'm seeking a 120gal now, but so far not a lot of luck yet. I'm in no hurry though, so not a big deal.
I think adding the 2nd return may help, as at least I have a back up now. The chances of both returns loosing siphon will be slim, possible, but slim chance.

So do you guys with drilled tanks have these same types of issues? Drilled tanks work more off of gravity right? So unless there is some sort of strange clog, the water should drain no problem. I'm guessing the issue with that setup is, if the pump quits, you just have to worry about flooding the sump if not calculated correctly?