How do I clean a clogged pool chlorinator?

Empty it, rinse it, check the lines

A clogged tablet feeder is nearly always cleared by emptying it, rinsing it and clearing the passages around it. Chemical feeders are installed on the discharge side of the pump and introduce chemicals automatically into the water,^[2] so the feeder sits on the line that returns water to the pool. When scale, tablet residue or sediment narrows that path, the dial may say the feeder is working while little chlorine gets through.

This guide covers an off-line, tablet-type feeder like the common Hayward CL series, because those are the ones homeowners open. Your model may differ, so use its manual for the parts layout. The safety order below holds for nearly all of them.

Before you open it

Hayward's manual lists the safety warnings as: wear eye and skin protection while maintaining or servicing the unit, do not inhale fumes from the chlorinator or chemical container, and be aware that the feeder may be under pressure.^[1] Work outdoors, keep your face back, and have a bucket of clean water nearby.

Shut off all pumps and pump timers, turn the feeder's flow control valve to OFF, and wait one minute to relieve system pressure before attempting to remove the cover.^[1] If the feeder is installed in a flooded system, the manual says to shut the valves that isolate it first.^[1]

Clean it out

Carefully remove all tablets and pieces of tablets, then rinse the chlorinator thoroughly with water.^[1] Keep the tablets in a dry, closed container away from other chemicals, and keep your hands out of the rinse water until you have put the lid down.

Look at the walls, grate and inlet and outlet fittings. A white crust is mineral scale. Loosen it with a plastic brush and rinse. Avoid wire, which scratches the plastic and gives scale a rougher surface to grab. Check the cover O-ring too. Never use petroleum-type lubricants on the cover O-ring,^[1] Use the lubricant your manual names.

Then look past the feeder. Verify that the feeder's return line to the pool is unrestricted.^[1] A kinked hose, a half-closed valve or a plugged fitting will make a clean feeder act clogged.

What to put back

Use only slow-dissolving trichlor tablets, never fast-dissolving ones, and never mix chemicals.^[1] This is not a fussy rule. Mixing chemicals or using fast-dissolving chemicals may result in explosion and fire.^[1] Never mix trichlor tablets with calcium hypochlorite or any other form of concentrated chlorine.^[1]

Virginia's health department guide for public pools warns never to use granular chlorine in an erosion feeder, because it will explode.^[2] That guide adds that calcium hypochlorite is very reactive to moisture and other compounds, and a small amount of water on the dry product can create an explosive reaction and release chlorine gas.^[2]

Also keep other products out of the skimmer. Never add other types of chlorine, pH adjusters, shock treatments or algaecides through the skimmer; these should be added directly into the pool water.^[1]

Keep it from clogging again

When vacuuming, close the flow control valve to prevent bypass of sediment and possible clogging of the control valve.^[1] Open it again when you are done. Rinse the feeder body each time you empty it, and look for residue before each refill. If the pool stays low on chlorine after a clean feeder is back in service, see whether a pool pump repair is worth it.

Stop and call a pro if

• The feeder is cracked, warped or leaking at the body. Replace it or have a pool business do it, rather than patching a pressurized vessel.
• Tablets have been mixed or have gone to mush, fumed or heated. Someone may have added a second chemical. Leave the area, ventilate it, and do not handle it. For a chemical exposure, get medical help right away.
• The feeder is plumbed in a way you cannot isolate. If there are no isolation valves and you cannot take the pressure off safely, a technician can do it properly.
• The problem is a salt chlorine generator or any controller with wiring. That is electrical work, and electrical work should go to a licensed pro. Virginia requires a contractor licence for work valued at $1,000 or more,^[3] and an individual doing tradesman work as defined in the Code of Virginia must be licensed as a tradesman unless supervised by a licensed one.^[4]
• Pipe or fittings downstream are broken. Ask for the repair to be written into a quote with parts listed.

Getting help in Virginia

If the feeder is clean and the water is still off, you may be dealing with the pump, filter or plumbing instead. Read how much pool pump repair costs in Virginia and browse more pool equipment answers. Loclis lists DPOR-licensed businesses by town: start at pool equipment repair.

When you want a pro to look at it, describe the chlorinator problem once and local pros reply with quotes.