Why is it so important to have syphon discharge 4ft lower than intake? we want to extend our 12" intake pipes because they suck air when in syphon mode, but I'm afraid we won't have the 4ft difference between intake and discharge. Im not too sure we have 4ft difference as it is!
Thanks,
Jason

The physical weight of the water in that 4' drop is what promotes a STRONG discharge of water and ensures enough flow to prevent air entering the pipe from the discharge end (along with an upturned elbow).

Air can only enter through unsealed pipes, or from from entering the discharge as the water flow "flattens" out upon pipe exit...that is why you want an upturned elbow on the discharge.

Edit:..The 4' drop does not neccisarily need to be from the point of intake, but from the lowest water level being drawn down to...one would presume you will have the intake in the deepest pool area and want to have the ability to drain nearly completely.

Thanks for the reply! I think we should be good!