The most costly mistakes in pool opening happen in the first 10 minutes — before the pump is even turned on. Skipping the pre-startup inspection is how a cracked fitting goes unnoticed until it's run under pressure and turns a $50 fitting issue into a flooded equipment pad and a damaged motor. Here's the correct priority order for every pool opening after winter.
If you're using PoolLens or any service notes system, start here. What was the water chemistry at closing? Which lines were blown? Where are the drain plugs stored? What issues were flagged for spring follow-up? The closing notes tell you exactly what to expect and what to verify before you start.
If there are no closing notes (a new account, or a self-closed pool), you're opening blind — which means the pre-startup inspection is even more critical.
Do this before filling the pool and before turning on anything electrical:
Never start the pump before reinstalling all drain plugs. A pump housing missing its drain plug will expel water through the open port immediately under pressure. A heater missing its drain plugs will leak into the combustion chamber and flood the heater. Both are avoidable with a 2-minute drain plug check.
If the pool was drawn down for winter, fill to the midpoint of the skimmer opening before starting the pump. Starting the pump with water below the skimmer allows air into the suction line and can damage the pump if it runs dry.
Verify all suction and return valves are fully open. Set the filter multi-port valve to Filter. Turn on the pump and watch carefully for 5 minutes:
If any leaks appear, shut off the pump immediately and address before continuing.
After the system is running, collect a water sample for full testing. After a winter under a cover, expect:
Follow the chemical sequence: pH first, then alkalinity, then calcium hardness, then shock. See the spring chemical sequence guide for the full protocol.
After opening, run the pump continuously for 24–48 hours to fully circulate and filter the winter water. Backwash the filter after this initial run — it will likely be high pressure from all the winter debris it's cleared.
PoolLens stores closing chemistry, equipment notes, and open items from the previous season — so every spring opening starts with full context and no surprises.
Open PoolLens Free →Before turning on any equipment, visually inspect all plumbing and equipment for freeze damage. Inspect first, then reinstall all drain plugs, then start the pump.
Signs of freeze damage: cracked PVC fittings, fittings that have separated from joints, water leaking when you refill and prime the system, or skimmer bodies that have cracked from ice expansion.
Only after testing and adjusting chemistry to: free chlorine 1–3 ppm, pH 7.4–7.6, total alkalinity 80–120 ppm. Allow at least 24 hours after shocking before using the pool.
The most likely causes: drain plugs not reinstalled before filling, an air pocket in the suction line, or a suction valve left in the closed position from winterizing.