Reprinted with permission of   Bill Nash, CEO   UGlassIt Pool Resurfacing Inc.

How To Drain a Fiberglass Swimming Pool

Basically, there are two methods to empty a fiberglass pool depending upon which type of filter is attached:

Sand Filter

Purchase a backwash hose from a pool supply store such as Leslie's or Adcock, and attach it to the filter.

Diathamatious Earth (DE) Filter

The other method would be with a sump pump (preferably 2"), and be sure to run the hose away from your property and your neighbors property. Be careful not to let the pump continue to run after the pool is empty because it will burn out.

  Sinceeven the smallest swimming pool has at least 8,000 gallons of chemically treated water, you should be cautious when determining where to dump the water. Some Townships even have regulations, so you should check with your Township and find out before you empty the pool.

Relief Valves

These valves only exist in fiberglass swimming pools which have a standard bottom drain resembling those used in bathtubs. Wall mounted bottom drains do not contain relief valves.

As soon as the pool is empty, use a shop vac to remove the remaining 6" of water that's pooling at the bottom drain. Remove the two screws and lift-off the bottom drain. Again, use the shop vac to remove the water that is still under the drain cover.

Manual Valve

With the water removed, you can look inside to determine which type of relief valve is there. One type has a "lug" nut that can be removed with a ratchet wrench. Pull out the valve and set it aside with the lug nut.

Hydrostatic Valve

These work great when the pool is new, but that is not when you usually need them. These type valves are located inside a pipe that is next to, or on a 90 degree angle to, the drain pipe (that goes to the pump). The drain going to the pump is the one that points directly toward your pump and filter.

The hydrostatic relief valve is inside the other pipe, just out of sight. Use the handle of a short stem screw driver to reach inside the pipe and hit it several times, with the handle. This will free the valve and let it open.

After removing a valve, place a pipe into the valve (about 3’ to 5’ long) and put a hose through the pipe. This will prevent the hose from laying on the bottom while you're working. Bring the hose up over the top of the coping and attach a sump pump to draw the water out from underneath the pool. This is just ground water, so there is no chemical content to be concerned about. Point the water flow to a drainage area away from the pool and other homes in your proximity.

Fiberglass Pool Stand Pipe

Many fiberglass pools had a water problem during construction and, to the current owners good fortune, have a "stand-pipe" located near the pump and filter. If this is the case, simply remove the cap and place a long hose into the pipe, then attach the hose to a utility pump and drain the underground water.

Quite often, a stand pipe equivalent was used when the fiberglass pool was built and a high water table was encountered. You may have a piece of black or white PVC emerging from the ground on the side of the deck closest to the grass and on the same side of the pool as the pump and filter. This PVC goes directly into a 4' by 4' by 4' pit, or a 2' by 4' by 4' pit, underneath the pool that was filled with stone. This PVC serves the same function as a stand-pipe and should be used as explained above.

Fiberglass Pool Skimmer