Pool pump suction lift

[Searstj]

Ive been reading quite a bit on suction lift capabilities for pool pumps and there is one specific thing I can’t seem to figure out. If a pump has capable lift of 8feet, and you have a pool that is 10 ft deep, would it then be unable to pull efficiently from the Main drain located in the deep end? I understand the pumps are rated for 8ft above the water level, but I feel with a main drain it wouldnt matter where the water line is as it’s in a pipe under the pool.
Am I overthinking this? Because I feel like this I never a concern of people when buying pumps... everyone always seems to be more concerned with gpm and hp, but you never hear people giving a second thought to lift capabilities.

 

[cowboycasey]

I am not 100% positive but lift should be above water level.. while it is 10 feet under water that water has thousands of pounds of pressure above it.. Until it reaches water level and then the suction takes over...

I have been know to be wrong

 

[JamesW]

The only thing that matters is how high the pump is above the water surface level.

The pool could be 100 feet deep and it would not matter.

If you put a 105 foot piece of pvc in a pool 100 feet deep and the top of the pipe is open, the water will fill the pipe to the level of the surface of the pool.

So, you get the first 100 feet for free.

You only have to lift the water 5 feet.

 

[JamesW]

Also, the amount of water being lifted does not change how hard the pump has to work.

For example, if the pipe had a diameter of 100 feet, you would be lifting about 2.4 million pounds of water but the static head loss is the same as if you were using 2" pipe.

The dynamic head loss increases with smaller pipe or longer pipe.

 

[Searstj]

Ok now this makes sense... thank you all. I was way over thinking this.