The pipelines in your pool can clog over time due to a build-up of contaminants, stopping or hindering the flow of water through the pool's drain pipe. Unblocking pool pipes may require changing your pump's water pressure, but it's a relatively simple process that typically does not take the skills of a pool professional.
Verify which pool pipeline is clogged by turning off all intake lines except for one skimmer line. Run the pump through the one skimmer line and check the flow of the water. If the water flow slows or stops, the skimmer line is clogged. If the water flow remains at normal levels, turn off all intake lines except for the other skimmer line to check the line. If the pool water still flows normally, run the pump off the main drain alone to check for a clog. Once you have verified which pool pipeline is clogged, move on to the next step.
If the skimmer line is clogged, switch off the pump. Open the end of the skimmer line intake. Disconnect the other intakes.
Take off the lid of the pump. Connect the drain jet to the pump's intake. Switch on the pump. This will reverse the water flow of your pump, creating excess water pressure against the pipeline blockage, and hopefully dislodging it and allowing it to pass through the pipe. If this technique fails to remove the clog, move on to the next step.
While the pump is in operation, position a tennis ball directly above the port of the skimmer. The ball will prevent the proper flow of water through the pipe. After enough pressure accumulates to stop water flow, move the tennis ball away from the port. The water pressure should help push the blockage through the pipeline. Repeat this technique as needed to dislodge the blockage fully.
If these methods fail to unblock the pool's pipeline, hire a pool professional to use a CO2 gun to remove the blockage. A CO2 gun can emit 159 Kilogram per square inch (PSI) of air pressure, which should be sufficient to dislodge the blockage.
Prevent future pool pipeline blockages by clearing any visible sediment from your pool with a pool net and cleaning your pool filter regularly.
Always wear safety gloves when handling pool equipment to avoid injury.