How Do I Match My Overflow And Sump Pump?

[Sea Turtle]

I have a problem that is giving me some difficulty grasping. I have an overflow box that flows 1200 gal/hr to a sump with a protein skimmer and a return pump that will pump 1020 gal/hour. How do I make sure that the overflow is not to fast for the return pump or that the return pump is not too fast for the overflow and burn itself out. I have the feeling that you need to adjust the height of the overflow box to adjust the water flow. if that is the case what about the water level changing everyday from evaporation and then slowing the flow? etc... If you wouldn't mind explaining this to me, i would greatly appreciate it.

Thankx

 

[ox5477]

Height won't change the flowrate substantially (when you consider changing 3 ft of drop to 3.5 ft or 4 ft). flowrate is based mainly on pipe diameter and pressure differences. Pressure in the tank and in the sump can be considered constant and equal (atmospheric) even if some evaporation occurs. To adjust flowrate down to the sump, try installing a ball valve in the pipe down to the sump. you can adjust this pretty precisly until you get a close match to the flow rate of your return pump. you always want the flowrate down to the sump to be greater than flow back to the tank though as this ensures that the tank never overflows (the overflow box will stop sending water once the water in the tank has reached a certain level so if you lose power, your sump won't flood)

question, for the overflow, are you using a continuous weir type overflow or do you just have a hole in the tank with a continous flow (no suction required)?

 

[Sea Turtle]

Yes. I am using a continuos weir type(dual overflow box for non drilled aquariums). It is an overflow box that hangs on the tank with 2 upside down u-shaped pipes. So basically you set it up so that the amount of water that is overflowing into the overflow box is determined by the amount of water the sump pump is returning to the tank? correct?

 

[ox5477]

Honestly, I wouldn't even worry about adjusting it. as long as your weirs never lose suction, you should be fine with the flow rates you have now. Once the water in the main tank gets to a certain level, the water will stop flowing down to your sump and give you pump a chance to catch up so you should be fine (in actually, you will just prob have a slower flow through your weir than what it can handle at max, so if your happy with the flow rate of your pump, then you shouldnt need to change anything, but as I said, if you wanna match the flowrates better, you can add a ball valve on the pipe from the weir down to the sump (but you def don't need to)

and just to clarify, if your have a weir that can lose suction, then you do need closer flowrates and would need to install the ball valve to slow down the flow to the sump so that your weir doesn't dry out and lose suction (would be bad... water from sump has no where to go except on your floor )

 

[andywg]

The overflow needs to be rated higher than the return pump. The water will then only run down the overflow at the same rate it is pumped up.

When thte system is off the tank will drain to the bottom level of the overflow. Once the pump is turned back on, the water level will rise and the water will flow down the overflow at the same rate as the pump is pumping up.

Simple as that.

 

[Sea Turtle]

This is what I am afraid of. What if the electricity was to go out in the house? Then the overflow would lose suction, the pump would come back on and

 

[andywg]

This is what I am afraid of. What if the electricity was to go out in the house? Then the overflow would lose suction, the pump would come back on and

A well designed overflow will not lose syphon, certainly not during normal operation.

However, the possibility of the above occuring is what makes me drill every one of my tanks.

 

[ox5477]

A well designed overflow will not lose syphon, certainly not during normal operation.

However, the possibility of the above occuring is what makes me drill every one of my tanks.

yep

 

[Sea Turtle]

This is what I am afraid of. What if the electricity was to go out in the house? Then the overflow would lose suction, the pump would come back on and

A well designed overflow will not lose syphon, certainly not during normal operation.

However, the possibility of the above occuring is what makes me drill every one of my tanks.

How difficult is it to drill a tank? Do I need a special drill to do this? How is it done?

 

[SkiFletch]

Just a special bit, but a regular drill. You want an industrial diamond abrasive holesaw bit appropriate for the thread size of the bulkhead you choose. Then you just drill really slowly keeping the bit wet/cool with water. There are LOTS of appropriate bits for sale on ebay for cheap (~$8-10 shipped for most sizes) and work great. I too only drill tanks .

Lets start with your pump though, I realize it may be rated for 1020GPH, but that is assuming that it's pumping wide open. What we really need to know here is either what pump it is, what its pressure/flow curve is, or what it's max head pressure is before we go any further. As you try and pump water upwards from the sump to the tank it gets harder and the pump can no longer move water as fast as it can with no restriction on it. So we need to find out what your approximate operating GPH will be before we consider a drain

 

[Sea Turtle]

Just a special bit, but a regular drill. You want an industrial diamond abrasive holesaw bit appropriate for the thread size of the bulkhead you choose. Then you just drill really slowly keeping the bit wet/cool with water. There are LOTS of appropriate bits for sale on ebay for cheap (~$8-10 shipped for most sizes) and work great. I too only drill tanks .

Lets start with your pump though, I realize it may be rated for 1020GPH, but that is assuming that it's pumping wide open. What we really need to know here is either what pump it is, what its pressure/flow curve is, or what it's max head pressure is before we go any further. As you try and pump water upwards from the sump to the tank it gets harder and the pump can no longer move water as fast as it can with no restriction on it. So we need to find out what your approximate operating GPH will be before we consider a drain

I looked into it. I will be pumping about 800 gal/ hour back into the tank at 4 feet.

 

[SkiFletch]

For real . Jebus, what kind of pump has a curve that steep?