Do you know what the problem might be if a swimming pool drains when filter is on?

- Loose Pipe Connections: Check all the plumbing connections around the pool, including those near the filter, pump, and main drain. Loose connections can cause water leaks, gradually draining the pool. Tighten any loose fittings and replace damaged or cracked pipes.

- Cracks or Leaks in Equipment: Inspect the filter, pump, and other pool equipment for any visible cracks or leaks. Check the pool light fixture, as a faulty seal can also lead to water loss. If you find any leaks, repair or replace the faulty components.

- Broken Skimmer Basket or Drain Cover: Ensure that the skimmer basket and main drain cover are properly sealed and not cracked. A broken skimmer basket or a loose drain cover can allow water to seep out, causing the pool to drain. Replace damaged components as necessary.

- Damaged Pool Liner: If your pool has a vinyl liner, check for any tears or punctures that may be causing water loss. A damaged liner can lead to a slow but steady leak that may not be immediately noticeable. Repair or replace the liner as needed.

- Incorrect Valve Positions: Ensure that the valves in your pool system are set correctly. Check that the main drain valve is closed when the filter is running and that the other valves are properly aligned. Incorrect valve positions can disrupt water flow and contribute to pool drainage.

- Faulty Backwash Valve: If you have a sand filter, check the backwash valve. A faulty backwash valve can allow water to escape during the backwashing process. Ensure the valve is closed properly and replace it if necessary.

- Damaged O-Rings or Gaskets: Inspect all the O-rings and gaskets in your pool equipment for any signs of wear, cracks, or deformation. Worn-out or damaged O-rings and gaskets can create tiny leaks that can add up over time. Replace any faulty seals to prevent water loss.

- Broken Pipes Underground: In some cases, hidden leaks in underground plumbing may be responsible for the draining pool. If you suspect this might be the issue, it's best to consult a professional pool technician or plumber for assistance.