Chemical sequence at spring startup matters more than the specific products you use. Adding the right chemicals in the wrong order reduces effectiveness, wastes product, and can cause reactions that cloud the water or damage surfaces. This guide gives you the exact sequence with the reasoning behind every step.
Never add chemicals to a pool you haven't tested. Even a pool that looks clear after winter can have pH outside the normal range, depleted alkalinity, or zero CYA. Adding shock to high-pH water wastes a significant portion of its effectiveness. The test results dictate what you add and how much.
At spring opening, test for:
If your water test shows copper or iron above 0.1 ppm, add a sequestrant (Jack's Magic, Metal Magic, Natural Chemistry Metal Free) before any chlorine. Shocking water with metals present causes the metals to oxidize and precipitate as stains on the pool surfaces. Sequestrant holds metals in solution so they can be filtered out gradually. Add per label, run the pump 24 hours before continuing.
Target pH 7.4–7.6. At spring opening, pH commonly runs high (7.8–8.2) from winter precipitation and debris, or low in certain regions. Adjust pH first because it affects how every other chemical works:
To lower pH: muriatic acid or sodium bisulfate (dry acid). To raise pH: sodium carbonate (soda ash). Add to the deep end with the pump running. Wait 30 minutes and retest before adjusting further.
TA stabilizes pH and prevents it from swinging rapidly. Target 80–120 ppm. Winter water exchange and rainfall commonly drop TA. To raise: sodium bicarbonate (baking soda) — add in front of a return jet. To lower: muriatic acid (this also lowers pH, so retest both after). Allow 2–4 hours of circulation before retesting TA.
Don't try to adjust pH and TA simultaneously. Change TA first if it's severely off — it will affect where pH settles. Then fine-tune pH. Both adjustments require patience and retesting, not just dumping everything in at once.
CH target: 200–400 ppm. To raise: calcium chloride flake. Dissolve in a bucket of water first (it generates significant heat), then broadcast across the pool with the pump running. CH cannot be lowered by chemical addition — partial drain and refill with softer water is the only option. Adjust CH last of the balancing parameters, as it changes slowly.
After pH, TA, and CH are in range, shock the pool. Spring shock dose:
Add shock at dusk or at night — UV degrades calcium hypochlorite rapidly in direct sunlight. Liquid chlorine is more UV-stable but still benefits from nighttime addition. Add to the deep end with the pump running.
Run the pump continuously for 24–48 hours after the initial shock. This is non-negotiable for effective spring startup. Short-cycling the pump prevents full circulation and leaves dead zones where algae can survive.
Algaecide added to high-chlorine water gets oxidized and destroyed before it can work. Wait until free chlorine drops to 3–5 ppm (typically 12–24 hours after shocking) before adding algaecide. For spring opening, use a polyquat-based algaecide (Polyquat 60) rather than the copper-based products — it won't stain and is compatible with all surface types.
CYA protects chlorine from UV degradation — pools without stabilizer lose their chlorine in hours of direct sunlight. Target 30–50 ppm for regular chlorine pools, 60–80 ppm for salt water pools. Add to the skimmer while the pump is running. CYA takes 48–72 hours to fully dissolve and read accurately on tests. Do not retest for CYA until 3 days after adding.
| Chemical | When to Add | Wait Before Next Step |
|---|---|---|
| Metal sequestrant | First, before chlorine | 24 hours |
| pH adjustment | After sequestrant | 30 min, retest |
| Total alkalinity | After pH is close | 2–4 hours, retest |
| Calcium hardness | After TA adjustment | 4 hours |
| Shock | After all balance chemicals | 24 hours (let chlorine drop) |
| Algaecide | When FC drops to 3–5 ppm | 4 hours |
| CYA | Last | 48–72 hours before testing |
SplashLens stores every chemical reading, product added, and opening note per account — so spring startup is efficient, documented, and reproducible across your entire service route.
Open SplashLens Free →Pool chemicals interact with each other and the water. Adding shock before adjusting pH means the shock works less effectively because chlorine efficacy drops at high pH. Adding CYA before shocking binds the chlorine before it can kill algae.
Run the pump continuously for 24–48 hours after the initial shock treatment to ensure full circulation, distribution of chemicals, and maximum filter run time to clear dead algae and debris.
For a properly closed pool, use 1–2 lbs of calcium hypochlorite per 10,000 gallons. For a pool with visible algae, double the dose and repeat after 24 hours if water is still green.
Add CYA last in the sequence — after pH, alkalinity, calcium hardness, and shock. CYA binds chlorine and adding it before shocking reduces shock effectiveness. CYA takes 48–72 hours to fully register in water tests.