Quick question.

[Tommy]

So... I have a friend who is plumbing 2 tanks into one sump so basically the water is circulating between the 2 tanks and a sump, he asked me if there is anything he can do to in case one return pump failed since he is using 2 return pumps.  he doesnt want water spilling on to the water if one of the pump is faulty or not working at all.  What can he do to prevent that?  Thanks in advance.  

[Origami]

So the two return pumps are servicing the two tanks on separate circuits from a common sump. Is that correct?

 

The bigger risk of overflow would not come from one pump failing, but both failing concurrently. In that case, some water may be siphoned from both tanks back to the sump, causing the sump water level to rise. If there's not sufficient capacity in the sump or if there's not a way to break the return line siphon, then there will be water on the floor. 

 

Now, if he's got the tanks plumbed serially. That is Sump > Tank1 > Tank 2 > Back to the Sump, then that's a disaster waiting to happen.

[dpassar12]

I run 2 returns, if one fails(which has happened) the tanks that are being fed from pump1 drain into sump. The ATO alarm willl go off because of higher water level in sump but the other tanks being fed from pump 2 continue on. Your friend should be able to test this by shutting each pump down and watching the water levels. If both pump stop, power outage the sump should be able hold all the water from both tanks anyway

[Tommy]

Thanks guys !  So after further investigation this is how he plumbed his tank.  45g tank drains down to the sump, return pump in the sump push water out to his 80g rubbermaid tub which is his other so called 'tank"  and the 2nd return pump is in a corner of the tub push water back in to his 45g tank.  Don't ask me why he does it like that lol...he is keeping freshwatter fish.   The sump is quite small ( about 30g ) so that's why he so worry.  Thanks , any suggestions or different ideas is greatly appreciated.  

 

So basically :   tank 1 => sump=> tank 2=> tank 1

[Tommy]

He said if both pump goes out its ok because the sump is able to hold the water from the 45g tank and the 80g tub would hold its own because the the tub is sitting low on the floor so it doesnt have an overflow, the return pump in the 80g tub is actually lifting water water up to his 45g.  Disaster only happen when one of the return pump is not working.  Thanks