It usually starts the same way. The pool looked fine in April, and now it is mid July, the pump is running its full schedule, and the water has gone dull. You check the gauge on the filter tank and it reads eight or ten pounds above where it sat when the pool was opened. The returns push weak, the sweep drags and stalls in the deep end, and a fine gray film keeps settling on the steps a day after you brush it. Nothing is broken. The filter is simply full.

That is the normal cycle in Manteca. The city sits at the junction of Highway 99 and Highway 120 with almond orchards on nearly every side, and those orchards give up dust all summer and petals every spring. The delta breeze that finally cools things off after a 104 degree afternoon carries that dust straight across the water. Add municipal water that runs high in calcium and alkalinity, and a filter here takes on two loads at once, organic debris packing the outside and mineral scale working into the media itself.

Nevergreen Pools handles filter cleaning in Manteca in partnership with Vintage Pool Service, whose shop and retail store sit on East Yosemite Avenue. That means a tech who has pulled filters on the older plaster pools in the center of town and on the newer pebble finish pools out in the subdivisions, and who knows what a cartridge in this part of the valley actually looks like at the end of a hot season.

Reading the Gauge, Then Opening the Filter

The first move is a pressure reading taken with the pump running and the system fully primed. That number only means something next to the clean starting pressure for that same filter. If clean was 12 pounds and the gauge now reads 20, flow is restricted enough to hurt circulation, heater performance, and the sweep. Waiting much past that point costs more than the cleaning does, because a starved pump runs hot and a heater that cannot get enough flow will start shutting itself down on its high limit.

On a cartridge system the elements come out of the housing and get spread open. A garden hose with a straight nozzle, not a pressure washer, gets worked down every pleat from top to bottom on both faces. Pressure washers drive grit into the fabric and split the pleats, and a split pleat sends dirt right back to the pool. Once the loose dirt is off, the elements go into a soak, because sunscreen, body oil, and the waxy film off orchard bloom bind fine dust into the fabric where water alone will not reach. A degreaser soak overnight and a rinse pulls that out. If the pleats still feel stiff and chalky afterward, that is calcium out of Manteca tap water, and it takes a separate dilute acid soak, done after the degreaser and never mixed with it, then a heavy rinse before anything goes back in the tank.

The signs that a filter has gone too long are consistent:

• Pressure sitting eight to ten pounds over the clean reading
• Weak return flow and a pool sweep that keeps stalling
• A heater that fires, runs a few minutes, then shuts off
• Water that stays hazy while the chemistry tests fine
• Pleats that stay gray after a full hose rinse