Seasonal Care
Opening an above-ground pool in spring
A shorter afternoon than closing was, done in reverse. Almost every green opening is a timing problem rather than a chemical one.
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The short version
- Clear the cover before you move it. Dragging a loaded cover off tips a winter of debris into the pool.
- Filter first, chemicals second. Circulation does most of the work of an opening.
- Cloudy water at opening is normal and clears in a few days.
- Green openings are timing errors — uncovered too early, or reconnected too late — not chemical shortages.
Why green openings happen
Almost never because the closing chemicals were insufficient. Two timing errors account for most of them.
Uncovered too early. Light on still, unfiltered water is exactly the condition algae needs. A cover pulled off in March for a pool that will not be reconnected until May gives algae two clear months.
Reconnected too late. The reverse of the same problem: the cover comes off and the filter does not go on for a week. Once the pump is running, algae is fighting circulation and chlorine; before that it is not fighting anything.
The rule that follows: uncover and reconnect on the same day. If you are not ready to reconnect, leave the cover on.
The sequence
The full step list is below. Two points deserve emphasis.
Clear the cover before you move it
A winter cover after five months holds standing water, leaves and grit. Dragging it off in one movement tips all of that into the pool, which turns a one-day opening into a week of filtering and vacuuming. Pump the water off, sweep the debris off, and only then move the cover.
Filter before you dose
The instinct is to shock immediately. Resist it. Twenty-four to forty-eight hours of continuous filtration on reconnected, topped-up water does most of the work, and it also means the shock you eventually add is working on a much smaller problem. Chemicals added to still water do considerably less than the same chemicals added to circulating water.
Things to replace rather than reuse
The filter cartridge. Start the season with a fresh one. A cartridge that finished last season is not going to survive an opening, and an opening is the heaviest filtration load of the year.
Anything that cracked. Inspect the pump housing, hoses and fittings before reconnecting. Freeze damage is why draining the equipment matters, and this is when you find out whether you did it properly.
Test strips. Strips degrade with humidity and age. A bottle that spent winter in a damp shed is giving you fiction.
Water and cost
Topping back up to operating level is real water. On a 3,955-gallon pool lowered to a winter level, expect to add a meaningful fraction of the volume, at the national average of $6.06 per 1,000 gallons. Fresh water is untreated, so budget for the balancing chemicals that follow it.
Opening and closing are both line items in a pool year, and most budgets leave them out entirely. They are included in our annual cost guide.
Before anyone swims
Test rather than assume. Free chlorine must be back in range — the CDC publishes at least 2 ppm when a stabilizer is present — and the water must be clear enough to see the bottom of the pool clearly. And put the ladder back with the same access rules you had last season; the CPSC’s layered approach starts again on day one, not once the pool is busy.
What to buy
Scores are our own reading of published specifications. They are not test results — we have not tested these products and we do not claim to.
The default first test kit
AquaChek Silver 7-Way Test Strips (100 count)
AquaChek
Seven readings in fifteen seconds, including the two that beginners never measure and then fight all summer: total alkalinity and cyanuric acid.
Key specs
- Tests
- Free chlorine, total chlorine, bromine, pH, total alkalinity, total hardness, cyanuric acid
- Free chlorine range
- 0-20 ppm
- pH range
- 6.2-8.4
- Total alkalinity range
- 0-240 ppm
- Cyanuric acid range
- 0-300 ppm
- Read time
- 15 seconds
- Count
- 100 strips
How it scoresour reading of published specs, not a test result
- Value
- 9.2
Overall 8.9 / 10
What works
- Covers cyanuric acid, which most cheap strips omit and which is the reason chlorine stops working in a stabilized pool
- pH range spans 6.2-8.4, comfortably bracketing the CDC's recommended 7.0-7.8
- 15 seconds and a color chart printed on the bottle — no separate booklet to lose
- 100 strips is a full season of twice-weekly testing with room to spare
What doesn't
- Strips are a comparison against a printed color chart, so they are directional rather than precise
- Reading them in bright sun is harder than it should be
- The bottle must be kept sealed and dry or the strips degrade quietly
Skip it if: Fine adjustment. If you are chasing a stubborn problem and need a number rather than a color band, a liquid reagent kit is the tool.
What it costs to run: 100 strips at twice-weekly testing covers roughly two seasons for one pool. The real saving is upstream: knowing your alkalinity stops you buying pH adjuster you did not need.
One honest season: The cheapest setup that genuinely works for a season of real swimming. Nothing spare, nothing missing.
Specs from: CDC — home pool and hot tub water treatment and testing
Actually clearing a green pool
Calcium Hypochlorite Pool Shock
Various (compare available chlorine %)
Unstabilized, fast-acting and strong. This is the tool for an algae bloom precisely because it does not add more cyanuric acid to a pool that probably already has too much.
Key specs
- Type
- Calcium hypochlorite, unstabilized
- Adds stabilizer
- No
- Adds
- Calcium hardness
- Dosing
- By pool volume, per the bag
How it scoresour reading of published specs, not a test result
- Value
- 8.8
Overall 8.6 / 10
What works
- No cyanuric acid added, so it does not worsen the problem it is usually solving
- Fast and strong enough to actually break an algae bloom in one treatment when dosed properly
- Cheap per pound of available chlorine
What doesn't
- Adds calcium hardness, which matters in hard-water areas
- Must be dissolved properly or it will bleach a vinyl liner where it settles
- Needs careful storage — it is a genuine oxidizer, not a household product
Skip it if: Routine daily chlorination. This is the emergency tool; tablets are the routine.
What it costs to run: The single most cost-effective way to fix a green pool, and the most commonly under-dosed. Half a dose twice does not equal a full dose once — it just wastes the bag.
One honest season: The cheapest setup that genuinely works for a season of real swimming. Nothing spare, nothing missing.
The consumable you will actually buy repeatedly
Type A Replacement Filter Cartridges (multipack)
Various
Buy them in a multipack before you need them. A pool running on an exhausted cartridge is a cloudy pool, and the fix is a two-dollar part you did not have.
Key specs
- Type
- Type A — the most common Intex format
- Replacement interval
- Every 2 weeks in heavy use, per Intex guidance
- Between changes
- Rinse, do not scrub
How it scoresour reading of published specs, not a test result
- Running cost
- 7.0
- Value
- 8.5
Overall 8.2 / 10
What works
- Type A is the most widely stocked cartridge format in the US
- Multipacks cost a fraction of buying singles
- Having a spare turns a cloudy week into a five-minute fix
What doesn't
- It is a genuine recurring cost that nobody includes in the purchase price
- Aftermarket quality varies noticeably
- Rinsing extends life but does not restore a cartridge that is done
Skip it if: Being restored. Once the pleats are permanently gray and stiff, rinsing is not saving it.
What it costs to run: The line item most people leave out of their pool budget. Count how many you use in your first season and you have your real annual filtration cost — this is exactly the number the cost-to-run guide asks you to record.
One honest season: The cheapest setup that genuinely works for a season of real swimming. Nothing spare, nothing missing.
The single highest-return accessory here
Bubble Solar Cover for Above-Ground Pools
Various
It cuts evaporation, and evaporation is simultaneously your water bill, your chemical bill and your heat loss. Nothing else on this site reduces three costs at once.
Key specs
- Construction
- Bubble sheet, thickness published in mil
- Thickness
- Higher mil lasts longer — 12 mil and 16 mil are common
- Fit
- Cut to size; buy oversize and trim
- Orientation
- Bubbles face down, toward the water
How it scoresour reading of published specs, not a test result
- Retention
- 9.0
- Durability
- 7.0
- Handling
- 6.0
- Running cost
- 9.8
- Value
- 9.5
Overall 9.0 / 10
What works
- Reduces evaporation, which is the mechanism behind the water, chemical and heat savings all at once
- Cheap relative to everything it saves
- Can be cut to fit any pool shape, so sizing is forgiving
What doesn't
- Awkward to get on and off without a reel, and awkward is how covers end up unused
- Degrades in UV like every vinyl product
- Not a safety cover and will not support weight — this is important
Skip it if: Being a safety barrier. A solar cover looks solid and is not; a child or pet on it goes through and under.
What it costs to run: The one accessory with a clear payback. Every gallon that does not evaporate is a gallon you do not replace at the EPA WaterSense national average of $6.06 per 1,000 gallons, and it is chlorine you do not re-dose. If you buy one thing from this hub, buy this.
Several seasons: Buy-once. Built and warranted to come back out of the box for a few years, if you store it properly.
Specs from: EPA WaterSense — cost per 1,000 gallons
Fixing the number beginners skip
Alkalinity Increaser (sodium bicarbonate)
Various
The most under-bought chemical in the category. If your pH will not stay put, this is almost always the actual fix, and it is chemically just baking soda.
Key specs
- Active
- Sodium bicarbonate
- Raises
- Total alkalinity, with minimal pH movement
- Common target range
- 80-120 ppm (industry convention, not a CDC figure)
How it scoresour reading of published specs, not a test result
- Value
- 9.5
Overall 9.0 / 10
What works
- Raises alkalinity with only a small effect on pH, which is exactly what you want
- Extremely cheap — it is sodium bicarbonate
- Fixing alkalinity first stops the endless pH chase that eats a first season
What doesn't
- Works slowly and needs circulation, so it is not a same-afternoon fix
- Easy to overshoot, and bringing alkalinity back down is more work than raising it
- The 80-120 ppm target is an industry convention rather than a published federal standard, so treat it as guidance
Skip it if: Emergencies. Nothing about alkalinity is urgent; it is the thing you fix first and then stop thinking about.
What it costs to run: Pennies per dose, and it is the cheapest lever on your whole chemical bill: stable alkalinity means stable pH, and stable pH means the chlorine you already bought actually works.
One honest season: The cheapest setup that genuinely works for a season of real swimming. Nothing spare, nothing missing.
Questions people actually ask
How do I open an above-ground pool in spring?
Why is my pool green when I open it?
Should I shock my pool as soon as I open it?
Is cloudy water normal when opening a pool?
Sources
Read next
- Closing, covering and opening againWinterizing, covers and spring opening - the four weeks of the year that decide whether you own a pool next summer.
- How to winterize an above-ground poolThe correct closing sequence, the freeze damage that ends pools, and why a cracked pump housing is entirely preventable.
- Cloudy pool water: work out which of four problems you haveA diagnostic decision tree for cloudy water - four causes, how to tell them apart, and the correct fix for each.
- Pool algae: brush, shock, filter, then rebalanceThe correct order for clearing green water, how to tell algae from pollen, and why algaecide prevents rather than cures.
- First-time pool owner: the complete first monthThe pillar guide: day-one shopping list, the four water readings, the weekly routine and the week-three problem everybody gets.