Most systems require adjustment to the valving to increase flow in the line through which you are vacuuming. You may want to close all the valves except the one on the line you are vacuuming through. On some systems, closing too many suction valves will cause the pump to cavitate, which occurs when it is starved for water. If the pump begins to shudder and make interesting noises, open the valves until this ceases.

If your suction still sucks, check that the filter is clean and the pump basket has been cleaned. Before vacuuming debris into the pump basket, always make sure the basket is locked into place properly so that debris cannot bypass it and clog the impeller.

If you notice that your pump begins to draw in air when you connect the hose into the skimmer, possibly drawing in so much air that the pump loses its prime of water, it probably originates from an old, dry rotted hose with holes in it, or a cavitating pump drawing air in through the plumbing or valving.

To check the hose, hold one end tightly against your thigh while you make a tight seal with the other end around your mouth. Blow into the hose; you should feel very strong resistance. If you can blow easily, the hose has one or more holes or splits in it, and you may be able to hear the air being drawn through when it’s hooked up for vacuuming.

When a vacuum hose is hooked into the skimmer and perhaps some valves are closed to increase suction, we are increasing the “vacuum pressure” in the line, creating a front pressure on the pump. This can cause the pump to draw air in places it normally wouldn’t under lower pressure. This situation should be corrected by locating the air source and making appropriate repairs. (Repair info, see pumps)

When vacuuming fine, silty dirt or debris, you may notice a cloudy stream of dirt coming back into the pool via the return. This can continue slowly, long after you stop vacuuming, and can create a frustrating cycle for the pool janitor at your pool. More common in sand filters than in other types, the dirt can be pushed right through the filter, especially one which may need a sand replacement. Indeed, this situation may indicate internal filter problems. It may also indicate a problem with the filter control valve. Old, loose multiport or push-pull valves can allow water to bypass the filter and return to the pool unfiltered. For more info on valves, click on link.

Another possibility is that the pump is oversized for the filter, and is pushing the water so hard, it pushes dirt right through the filter medium. A sand filter actually works a little better when it’s a little dirty; the added dirt helps to trap more dirt, so don’t backwash prior to vacuuming a pool with a sand filter. You may also use filter aids, added through the skimmer, which provide a gelatinous layer on top of the sand bed to help trap dirt. Another tip is to vacuum to waste, especially if the debris is a fine silt that can clog the filter quickly. To do this, overfill the pool first, and set the multiport valve to the ‘Drain’/ ‘Vacuum to Waste’ position. Roll out the backwash hose, and vacuum the dirt (and water) right out of the pool…to waste.

If you haven’t purchased a leaf rake, or a “drag bag”, as I sometimes call them, and are holding on to that flat “dip & flip” net that your builder gave you; you are creating your own hell. I strongly encourage the purchase of a nice leaf rake. There are also chemical products which are used to keep surface tension high, moving small debris to the sides of the pool. Another possible problem could be the condition of the weir in the skimmer; you know, that flapper gate thing. Make sure it is operating properly so that it creates a draw or “waterfall” into the skimmer basket. Also check that the water level is not so high that it is above the opening of the skimmer.

Lastly, you may need to trim some of those trees and bushes near the pool. My pool, for example, was specifically built with no vegetation anywhere within wind shot!