A question about SUMP design I have NEVER understood

[Redearsunfish]

o.k. i'm considering a sump, but how does one A. ensure that the water doesn't drain out of the tank in case of a power failure, and B. how does one regulate the flow out of the tank and the flow back up from the sump so that the pump doesn't run dry, can the sump level possibly remain at a constant????

Thanks in advance.

 

[Gator]

Sumps use standpipes or overflow boxes that dont create a suction. If you had a pipe that had no siphon break then yes it would drain out the water. The overflow box and standpipes are matched to make sure that more water can flow into the sump than what the pump returns to the tank but at the same time they area also height adjusted so that in the event of a power failure when the water drains into the sump it doesn't drain to much out to overflow your sump. And for your last question yes the water will remain at a constant level as long as you keep adding water to the tank to compensate for evaporation thats why some people use reservoirs with pretreated water and and auto top off switch. This however does not mean that you don't have to do water changes anymore.

 

[bgcoop8784]

just basically, the the outflow from the tank should be able to handle more flow than the water being pumped into the tank, if using standpipes just have them the height of where you want the water level and however much water is going into the tank will be the amount that comes back out.

 

[Toby_H]

Sumps use standpipes or overflow boxes that dont create a suction. If you had a pipe that had no siphon break then yes it would drain out the water. The overflow box and standpipes are matched to make sure that more water can flow into the sump than what the pump returns to the tank but at the same time they area also height adjusted so that in the event of a power failure when the water drains into the sump it doesn't drain to much out to overflow your sump. And for your last question yes the water will remain at a constant level as long as you keep adding water to the tank to compensate for evaporation thats why some people use reservoirs with pretreated water and and auto top off switch. This however does not mean that you don't have to do water changes anymore.

Great answer...

also keep inmind ball valves can be placed on both the overflow/intake and the return lines to regulate flow... The ball valve on the overflow/intake side is usually used not to slow down the water, but to prevent this line from sucking air which can easily become an undesirable noise.

When the pump is turned off, there will be a small amount of water that needs to collect in the sump. This is why sumps are not topped off while in use, to allow extra space for this small amount of water to have some place to collect when the water is turned off.

 

[Redearsunfish]

excellent answers. In the past I used suction/gravity with a straight elbow into the sump. HOW STUPID OF ME. All i would have to do is create an upturned U shape to suck water from the surface at a greater rate than pumped back up...

 

[Toby_H]

excellent answers. In the past I used suction/gravity with a straight elbow into the sump. HOW STUPID OF ME. All i would have to do is create an upturned U shape to suck water from the surface at a greater rate than pumped back up...

Relying on a siphon to remove water from a sump is always risky... As if the pump turns off the siphon can drain the tank moreso than desired... or if the siphon is broken the sump pump can overflow the display tank...


Even overflow boxes have this risk. They are just designed in a way that minimizes the potential for the siphon to be broken. In most sumps the siphon from the display tank to the overflow box is the siphon that can cause major issues if the siphon is lost.

Which is why I would personally not feel comfortable using a sump on a non drilled tank in the house. I know many people do it and very few people have a problem with it... It's still a risk I choose not to take.

Life is full of risks, but we get to choose which ones we take...

 

[knifegill]

I'm still too chicken to sump it. Five years of thinking about it and the flood/burned out motor/'other' scenario won't leave my mind.

 

[Geoey]

sumps are fine if you set them up in a drilled tank anything else that uses syphoning to operate is dangerous, if you have a power failure the syphon gets disturbed and when the power comes back on you either overfill your tank or burn your motor out or both.

 

[Gator]

sumps are fine if you set them up in a drilled tank anything else that uses syphoning to operate is dangerous, if you have a power failure the syphon gets disturbed and when the power comes back on you either overfill your tank or burn your motor out or both.

Overflow boxes rely on suction and are perfectly safe to use.

 

[Toby_H]

Overflow boxes rely on suction and are perfectly safe to use.

That's an unfair statement to make...

There are a couple of fail safe designs... but the majority I've seen rely on a siphon which is a breakable connection that if broken, will allow a tank to overfill...