The first 70-degree afternoon hits and suddenly you remember: the hot tub. Maybe you used it lightly through the winter, maybe you shut it down in November and haven't lifted the cover since. Either way, a spring hot tub opening checklist is what stands between you and a soak that's actually enjoyable — clean water, balanced chemistry, and no surprise equipment failures halfway through.
Opening a Master Spas hot tub in spring isn't complicated, but the order matters. Skip a step and you'll fight cloudy water or foam for weeks. Follow the checklist below in sequence and you'll be soaking by the weekend.
Step 1: Inspect the Cover, Cabinet, and Surroundings
Before you touch the water, walk around the spa. Lift the cover off completely and set it on its side to inspect both panels. Look for waterlogged foam (the cover will feel noticeably heavier on one end), torn vinyl, or mildew along the seams. A saturated cover is the #1 reason spring heating bills spike — it can no longer insulate.
Check the cabinet skirting for loose panels, rodent damage, or chewed wiring. Winter is rough on the underside of a spa, and mice love a warm equipment bay. Rinse the skirting with a garden hose and wipe down the shell while it's empty later in the process.
Step 2: Drain the Spa Completely
If your water is more than 3–4 months old, drain it. Master Spas recommends a full drain and refill every 3–4 months, and if you ran the spa through winter, spring is the natural reset point. Attach a hose to the drain spigot at the base of the cabinet, run it to a safe drainage area (not your lawn if you haven't shocked recently), and let gravity do the work. A submersible pump will speed this up to about 20 minutes for a standard hot tub.
While the spa drains, this is the perfect window to replace worn parts you've been putting off — cracked jet faces, a sticky diverter valve, or a topside control with a dim display. Empty is the easy time to fix things.
Step 3: Deep Clean the Shell
With the spa empty, spray the acrylic shell with a dedicated spa surface cleaner (never household cleaners — they foam when refilled). Wipe down the waterline, the footwell, and inside each jet opening. Use a soft rag, not an abrasive pad.
Pull the filter housing caps and flush any debris from the suction area. If you see biofilm — a slimy, pink or black residue — run a spa line flush product through the plumbing before refilling. This is the step most owners skip, and it's why their water goes cloudy a week after opening.
Step 4: Replace or Deep-Clean Your Filter
Your filter is the hardest-working component in the spa. Most Master Spas filters should be replaced every 12–18 months, and the EcoPur Charge core specifically should be swapped at least once a year. If yours has been in for more than a year, don't clean it — replace it. A tired filter can't trap the fine particles that keep water clear, and no amount of shock will fix that.
• Master Spas EcoPur Charge Filter (X268532) — OEM replacement core, swap annually
• Master Spas Hot Tub Chemical Start-Up Kit — everything you need for a fresh fill
• Hot Tub Test Strips — test before and after every chemical addition
If you run a standard pleated cartridge, a quick inspection tells you if it's replaceable. Hold it up to the light — if the pleats are matted, torn, or permanently gray, it's done. Browse the full Master Spas filter collection to match your exact model.
Step 5: Refill With Fresh Water
Drop your garden hose into the filter housing — not the footwell. Filling through the filter housing purges air from the plumbing and prevents an "air lock," which is the most common reason a spa won't heat after spring opening.
Fill to the manufacturer's recommended waterline, usually halfway up the skimmer or just below the headrests. Overfilling can cause the jets to spray into the cover; underfilling will trigger a flow error and shut down the heater.
Step 6: Balance the Water Chemistry
Turn the power on, start the jets, and let the water circulate for at least 15 minutes before you test. Your target ranges for a Master Spas hot tub:
• pH: 7.4–7.6
• Total alkalinity: 80–120 ppm
• Calcium hardness: 150–250 ppm
• Sanitizer (chlorine): 3–5 ppm, or bromine 3–5 ppm
Always balance alkalinity first, then pH, then add sanitizer last. Starter kits simplify this by giving you pre-measured doses of each chemical in the right order. Shock the water with non-chlorine oxidizer after 24 hours of circulation to burn off any organics that hitchhiked in during the fill.
Step 7: Set Temperature and Run a 24-Hour Test
Set your target temperature (most owners run 100–102°F) and cover the spa. It will take 12–24 hours to reach temperature depending on starting water temp and outdoor conditions. Once it's up to heat, retest the water, add any small adjustments, and then — and only then — climb in.
Frequently Asked Questions
How often should I open and close my Master Spas hot tub?
If you use the spa year-round, you don't "open" it in the traditional sense — you just perform a quarterly drain-and-refill with a water refresh. If you shut it down for winter, open it in early spring once overnight lows stay above freezing consistently. Most Master Spas owners in the Midwest and Northeast open between late March and mid-April.
Can I use old water if it still looks clear?
Clear doesn't mean clean. After 3–4 months, dissolved solids and chemical byproducts build up in the water even when it looks fine. These make it harder to hold pH and sanitizer levels, and you'll end up using twice the chemicals trying to keep the water balanced. Drain and refill is faster and cheaper in the long run.
Why won't my hot tub heat after filling it for spring?
Nine times out of ten, it's an air lock in the plumbing. Turn off the power, loosen the union on the pump to let trapped air escape, retighten, and restart. If you filled through the filter housing and still have the issue, check for a clogged filter or a stuck flow switch. Owners manuals are available free from the manufacturer if you need your specific model's troubleshooting flow.
Do I really need a chemical start-up kit, or can I piece it together?
You can piece it together if you already own pH up, pH down, alkalinity increaser, sanitizer, a metal sequestrant, and a defoamer. Most owners don't, which is why a complete start-up kit works out cheaper than buying each bottle individually.
How do I know if my EcoPur filter needs replacing versus just cleaning?
The EcoPur Charge core is a consumable — the copper and zinc media inside wears out after about 12 months regardless of how clean the filter looks. If your water has been slow to clear or you're using more sanitizer than usual, the core is likely spent. Replace the full EcoPur Charge Filter rather than trying to rinse it.
What's the best way to stop foaming after a spring opening?
Foam after a fresh fill usually means residual soap or body oils in the plumbing, or high total dissolved solids from old water that wasn't fully drained. Run a line flush before your next drain to clear biofilm, and make sure everyone rinses off before soaking. A shot of defoamer is a bandaid — the fix is cleaner plumbing and fresh water.
Get your spring opening dialed in once and the rest of the season takes care of itself. Shop Master Spa Parts Online for every filter, chemical, and replacement part you need — all OEM, all in stock, with free shipping on orders over $99.