Why Hill Country pools go green so fast
Pools turn green when algae outpaces the chlorine fighting it — and in the Texas Hill Country summer, that happens faster than almost anywhere. The intense, near-vertical Texas UV burns chlorine off the water surface within hours; without enough stabilizer (cyanuric acid) to shield it, a pool can lose its entire free-chlorine reading in a single hot afternoon. Add 95°F-plus water temperatures, which algae love, and a missed week of service or a dead pump is all it takes.
We see the same triggers over and over in Comal County: a family leaves for a week at the coast in July, a pump capacitor fails, oak and cedar pollen plus a sudden summer storm dumps organic debris in, or a salt cell quietly stops producing chlorine. By the time the pool is noticed, it's already cloudy green.
The recovery protocol, step by step
- Test the water. We check free chlorine, pH, total alkalinity, cyanuric acid, and phosphates. This tells us how much shock the pool actually needs and whether stabilizer is too high to recover (over-stabilized water resists chlorine and sometimes forces a partial drain).
- Balance pH first. Chlorine is far more effective at a pH around 7.2. We bring pH down with muriatic acid before shocking, so every ounce of chlorine works harder.
- Shock hard. We hit the pool with a heavy dose of liquid chlorine — often several times the routine amount — to break the algae bloom. Severe pools get repeated doses over consecutive evenings (we shock at dusk so the sun doesn't burn it off immediately).
- Brush every surface. Algae clings to walls, steps, and especially the shaded plaster behind ladders and in deep-end corners. Brushing breaks the colonies loose so chlorine can reach them. This step is non-negotiable — chemistry alone won't clear a green pool.
- Flocculate or clarify. Once the algae is killed, the water turns from green to cloudy gray-blue with dead algae suspended in it. We add a flocculant to clump those particles and drop them to the floor.
- Vacuum to waste. We vacuum the settled debris straight out of the pool to waste — bypassing the filter — so the dead algae never recirculates. This is the single biggest reason DIY recoveries stall: vacuuming through the filter just pushes green water back in.
- Clean the filter. A recovery loads a filter heavily. We backwash or deep-clean cartridges so the system can polish the water clear over the following days.
Realistic timelines
- Light green (24–48 hours): Water hazy or pale green, bottom still visible. Often clears with a single strong shock, brushing, and a filter run. Recovery price near $325.
- Medium green (2–4 days): Cloudy green, bottom barely visible. Needs shock plus floc-and-vac and a filter clean. Around $425.
- Severe green / "swamp" (3–5 days): Dark green or black, bottom invisible, possibly a smell. Multiple shock cycles, repeat vacuuming to waste, and at least one filter deep-clean. Around $625, and occasionally longer than 5 days if the bloom is extreme.
We give a 5–7 day window on tougher pools because water has to clear gradually as the filter does its work — pushing it faster usually just wastes chemical.
When to drain and acid wash instead
Chemistry can't fix everything. If the water is so over-stabilized that chlorine won't hold, if there's standing dead algae and debris too deep to vacuum, or if the algae has stained the plaster itself, a drain and acid wash is the faster, cheaper path. A full plaster acid wash strips a thin layer of surface to expose clean plaster underneath. We only recommend it when recovery chemistry genuinely won't get there — draining a pool in the Hill Country has its own risks (hydrostatic pressure, plaster damage from sun exposure) and isn't a default.
Preventing the next green pool
Almost every green pool we recover was preventable. The fixes are simple:
- Keep stabilizer in range (30–50 ppm). This is the sunscreen that keeps Texas UV from torching your chlorine.
- Run the pump longer in summer. 8–10 hours a day when water hits the 90s — circulation starves algae.
- Never skip a week in July or August. The gap between "fine" and "green" in peak heat is often just five days.
- Set a vacation plan before you leave. A consistent weekly service means you come home to clear water, not a $625 recovery.
Bottom line
A green New Braunfels pool is almost always recoverable in under a week with the right protocol — the key is brushing, vacuuming to waste, and not skipping steps. If your pool has turned and you want it swim-ready before the weekend, we can assess it the same day and give you an honest recovery price by severity.