Friction Head: Each fitting and length of pipe causes a certain amount of friction loss. Over long runs or through several fittings can add additional feet of head if not allotted for. For corners try to use two 45 degree elbows in place of one 90 degree for a reduction in friction loss. If you must use a 90 degree elbow use the 'sweep' or 'long turn' style for reducing friction as well. For minimal runs or very few fittings you could get away with just adding one or two feet of head once you've found the Static and Pressure head. Friction head should be kept at or below 5 feet of head per 100 linear feet of pipe. If it is found to be higher then a larger diameter pipe is needed. View friction loss chart (pop up)

Pressure Head: All filters, UV's, and fountain head cause a given amount of pressure head loss. These numbers can vary according to flow rate, and whether you are running a high, medium, or low pressure pump. Typically a pressure filter will cause between 3 and 8 feet of head loss, a UV light around 2 feet of head loss, and a fountain head will cause minmal head loss as long as it is made for the size pipe the pump requires.

If a high pressure pump is pumping through a Ultima II filter with a 2 " valve most likely it will lose the maximum of 8 feet of head because the pump is exerting more force on the water therefore racting more with the filter valve causing the greater head loss.

Think of blowing through a straw, one size straw will only flow so much air no matter how hard you blow, although the harder you blow the more air will come out, but the harder you blow the more back pressure you feel because the straw is exerting it's maximun head pressure caused by the increased pressure of you blowing.