# Question about aquarium sumps!



## ChuckRum (Sep 11, 2010)

when the water siphons down from the main tank into the sump, how do you match the rate that the water is pumped back into the tank with your pump.

i mean, if your siphon is too fast, and your pump cant keep up than it will overflow. Or if your siphon cant keep up with the speed that your pump is pumping water out back in to the tank, then wont the siphon tank run dry?

so how do you match these two water flow rates so your sump water level doesnt drain or overflow?


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## Chris S (Dec 19, 2007)

Well, first you have a sump that can handle the capacity of all the water that would overflow - ie. power outage etc.

Second, you match the return pump rate with the drain rate of the return pumps (large diameter pvc piping, stronger pump can be used).


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## ChuckRum (Sep 11, 2010)

yea i figured, it just seems hard because youll never match it exactly. so wont your water always be slowly rising, or decreasing?

and incase a power outage, cant you prevent that by simply not placing your siphon all the way down your main tank?


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## Chris S (Dec 19, 2007)

ChuckRum said:


> yea i figured, it just seems hard because youll never match it exactly. so wont your water always be slowly rising, or decreasing?


It doesn't have to be exact, it just has to drain at the same speed as it returns to the tank. The return line is pressurized by the pump (ie. your return line can have let's say 1" pvc pipe), but your overflow isn't pressurized (you would need to use let's say 1 1/2" inch pipe). The water level in the display is then essentially adjusted by the way in which your overflow is setup, and you shouldn't have your display tank overflowing as long as your overflow can handle the same, or more, water than your return pump can push. In the case of having a return pump that is too strong, often times people will T off a section on the return line so that "x" amount of water is returned to the sump (controlled by a ball valve). This allows you to play with the amount of water going back into the display tank as well.



ChuckRum said:


> and incase a power outage, cant you prevent that by simply not placing your siphon all the way down your main tank?


Not sure why you would place it all the water down anyway, but you can also drill holes that will suck in air and break the siphon if the water level falls below a certain point (assuming you mean back-siphon through the return lines if the power blows).


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## ChuckRum (Sep 11, 2010)

ahh i see, thanks ive always wanted to know this.

setting up a sump sounds like alot of trial and error loll.


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## Will (Jul 24, 2008)

The display tank can't overflow more water than the sump pump puts into the display tank. It's equal. theres no matching overflow and pump speeds at all. the speed it overflows is directly related to the speed that your sump pump fills the display tank.

The siphoning action only happens to the excess water that raises above the water level (decided by the tanks overflow height) which is pumped into the tank by the sump pump. When the pump turns off, the main display tank drains the water only down to its overflow height, no more, until more water is added to the tank again.

The siphoning action in an overflow is just a releif for the pressure of having too much water in the tank. Kinda like the overflow preventor in a bathtub or sink. The only thing you have to "match" is that your overflow, must be GPH (gal per hour) rated for more than the pumps GPH output.

When the sump pump is turned off, the extra water that is normally sitting above the overflow point, is drained into the sump, which must hold the extra volume of water.

This is how you set it up assuming the tank has an overflow and the sump is set to receive the water, and has a pump to return to tank above.

Step one. Fill display tank till it starts overflowing. Stop.

Step two, fill sump tank, till its two inches below the top. Stop.

Step three, turn on the pump, and wait several minute.

The tanks level goes up slight, the sumps level goes down slightly.

Then, while the sump pump is running, take a marker and draw a line on the water level.

While the system is running, you must not put more water (or volume displacing items) than wat fits below this line, otherwise when you turn off the pump, the sump will overflow.

It's not complicated, but it's very hard to visualize without having seen it and the effects. There's no trial an error really, just an understand of how it works.

Check some youtube videos for "sump tours"


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