Hard water is the first thing to account for on any algae job in Lodi. Local fill water carries a heavy load of calcium and often brings iron with it. High calcium hardness pushes total alkalinity and pH up over the course of a season, and pH is what decides how much of your chlorine is actually working. At a pH of 7.2, roughly two thirds of free chlorine exists as hypochlorous acid, the form that kills algae. Let that pH climb to 8.0, which hard Lodi fill water will do on its own, and you are down to around twenty percent. The test still reads chlorine. The pool still turns green. That gap is why so many homeowners here shock a pool twice and get nowhere.

The second factor is what lands in the water. Vineyard tilling and harvest put fine dust and pollen in the air that settles on the surface and sinks. Cottonwood fluff comes through every spring. Pools under mature oaks and sycamores collect leaf litter and tannin all fall. All of that organic material is food. It also carries phosphate, which is the fertilizer algae runs on, and it burns through sanitizer just sitting there. Summer air in the high nineties keeps surface water warm, and cooler nights tempt people into cutting pump run time. Those are the exact conditions algae wants.

Nevergreen Pools handles algae removal in Lodi in partnership with Vintage Pool Service, a Central Valley company that has run routes out of East Yosemite Avenue in Manteca for years and knows what Lodi fill water does to a plaster finish. The approach is the same whether the pool is a newer pebble surface or a forty year old plaster pool: identify the algae, correct the chemistry that let it grow, kill it, filter it out, and fix the circulation problem underneath.

Why did my pool turn green so fast?

Blooms look sudden, but they are usually the end of a week or two of low sanitizer. Pool water here in July sits in the mid eighties. At that temperature chlorine burns off fast in direct sun, and if the stabilizer level is low there is nothing protecting it. Free chlorine drops under one part per million, a spore gets a foothold, and once it starts dividing it consumes chlorine faster than a tablet feeder can replace it. Overnight the water goes from slightly dull to green. The other common trigger is a pump that runs too few hours. Cool nights make short run times feel reasonable, but if the water is not turning over completely once a day, the pool has dead zones behind the steps, under the ladder, and along the deep wall where nothing circulates and nothing gets sanitized.

Does it matter what kind of algae I have?

It changes everything about the treatment. Green algae is free floating, it clouds the whole pool, and it dies at a normal shock level. Mustard algae, the yellow or tan dust that collects on shaded walls and brushes away in a cloud, tolerates chlorine far better and comes back from anything left on a pole brush, a float, or a vacuum head, so the gear gets sanitized along with the water. Black algae is not really algae at all in the way it behaves. It roots into plaster and gunite, especially where the finish has etched or gone porous, and it grows a waxy cap that chlorine cannot penetrate. You have to physically break that cap open with a stainless brush before any chemical will touch it, and you have to do it again every couple of days as new heads surface.

• Green: cloudy water, brushes off easily, clears at shock level with good filtration.
• Mustard: yellow dust on shaded walls, needs a higher and sustained chlorine level plus sanitized equipment.
• Black: dark raised spots rooted in the plaster, needs repeated aggressive brushing and spot treatment.

Identify it before you dose it. A strip that reads total chlorine only will not tell you what you need. Use a kit that separates free from combined chlorine and reads cyanuric acid, total alkalinity, and calcium hardness, because those four numbers set the dose and the order of operations. Match the brush to the surface too. A stainless bristle brush is right for plaster and gunite, but it will scratch vinyl, fiberglass, and some pebble finishes, which need nylon.