Monrovia is two pool towns wearing one postcode. On the flats around Old Town and Myrtle Avenue, pools are older, shaded by mature street trees and running equipment that has been on the pad for decades. Above Foothill, on the slopes climbing towards Monrovia Canyon, the houses are newer and so are the pads — variable-speed pumps, salt cells and an app on somebody’s phone. The two halves fail in almost opposite ways.
What they share is the canyon. What comes down it is not the soft leaf litter that troubles Pasadena but grit: fine decomposed granite and sediment, carried by wind and washed down by rain. It is too heavy to skim, too fine to notice until it is lying on the floor, and abrasive on its way through the equipment. In 91016 the debris question is as much about sand as about leaves.
What usually goes wrong on a Monrovia pool
Four problems: two from the canyon, one from the hillside, one from the pad.
- Grit settles where the skimmer cannot reach it
Canyon sediment sinks straight past the surface. Left there it gets drawn through the pump and abrades seals and impellers, and what reaches the filter packs the pleats tighter than leaf debris does. It is a vacuum job, and it brings filter cleans forward.
- Rain off the slope arrives all at once
A hillside garden sheds water to its lowest point, and often that is the pool. Dirt, organics and whatever was on the deck arrive together: pH and alkalinity shift, chlorine is consumed fast, the water clouds within a day.
- New automation left on the builder’s defaults
The hillside pads are good kit — Pentair and Jandy pumps, heaters, salt cells and controllers. What they lack is anyone who has tuned them: pump speeds too low to skim, schedules that never changed with the season, salt output guessed at, a fault code nobody has read.
- Down in the flats, the opposite problem
Original plaster, a single-speed pump and a mechanical time clock under a full tree canopy. Everything still works, nothing is monitored, and the first sign of trouble is usually the pump. We diagnose before replacing.
What we do for Monrovia pools
Old pad or new, the weekly checklist is the same. What changes is what it catches. Costs are on the pricing page.
Weekly maintenance
Full chemical panel, vacuum for the grit, baskets emptied, every piece of equipment inspected — including pump speeds and time clocks set for the season, not for installation day.
How weekly service worksGreen to clean
The Monrovia sequence: rain off the slope, then a warm week, then a green pool. Recovery takes about two days and does not need the pool drained.
Green pool recoveryAcid wash
Mostly an Old Town job: older plaster that grit and staining have left blotchy. It removes a thin layer of surface, so it is done rarely and only where there is plaster to spare.
What an acid wash doesEquipment repair
Pumps, heaters, filters, salt generators, lights, plumbing and automation controls. We install Pentair and Jandy equipment, so hillside pads are familiar ground.
What we repairNew plaster start-up
For the newest builds on the slopes: seven days of daily brushing with a nylon brush, calcium hardness at 200–400 ppm, no swimming for fourteen days, no salt for twenty-eight.
The start-up programmeAsk which day covers your side of Foothill
Routes run by day of the week, and in Monrovia the hillside streets and the Old Town flats are not always on the same one. After a windy or wet stretch, knowing your day tells you how long the grit will sit on the floor. Send the cross streets and we will tell you the day and whether it still has space — and mention a steep driveway or a coded gate while you are at it.
Worth mentioning when you call
- Which equipment you have
The brand on the pump and controller tells us a lot before anyone arrives.
- Pools and spas
Both covered by the same weekly plan.
- No one-time routine cleans
A pool that has gone needs a recovery before a route.
Questions Monrovia homeowners ask
After a windstorm there is a layer of grit on the bottom. Can I just vacuum it?
Yes, and better than leaving it. Vacuum slowly — sweeping fast lifts the sediment into a cloud that resettles overnight. Then check filter pressure, because grit fills a cartridge faster than anything else. What not to do is brush it towards the main drain and let the pump swallow it.
My pool is new and everything runs from an app. What is there to service?
The app controls the equipment; it does not test the water, empty a basket, brush a wall or notice a salt cell scaling. Modern pads also drift: schedules stay on last summer’s times, a pump speed set for quiet running is too slow to skim, a heater lockout sits unread. Good equipment shortens the visit; it does not remove it.
Rain came off the slope into the pool and it went cloudy. What now?
Get the debris out before it dissolves, then test rather than guess — runoff moves pH and alkalinity and eats chlorine at once. Run the filter longer for a couple of days and expect to clean it afterwards. If cloudy has become green, that is a recovery, not a clean.
The builder’s company handled the plaster start-up. When does normal service begin?
After the start-up programme finishes: the first week is daily attention, the following weeks close monitoring, and salt should not go in for twenty-eight days. Weekly service picks up from there. If you are unsure which stage the pool is at, tell us the plaster date.
Nearby, and on the same routes
The eastern Foothill days also cover Arcadia, Sierra Madre and Pasadena. Full list.
Send the cross streets, the size of the pool, whether it is salt or chlorine and what is on the equipment pad. That is enough for a real number and a service day.