August is the sweet spot that most pool owners underuse. The swim season is still fully open, but fall is close enough that the decisions you make right now — about your water chemistry, your equipment, and your supply inventory — will directly determine what greets you when you pull that cover off next May. I’ve reviewed enough pool products and talked to enough owners to know that the easiest spring openings belong to people who treated August as prep time, not just swim time.
Here’s what deserves your attention this month, before the end-of-season rush hits and before inventory at pool suppliers starts thinning out for the year.
Give Your Filter a Deep Clean Before Fall
By August, your filter has spent three months processing sunscreen, body oils, pollen, debris, and algae byproducts from the heaviest swim period of the year. Even if your water looks clear, your filter’s efficiency has almost certainly degraded. A compromised filter means your pump is working harder for less turnover — which means more chemical demand and cloudier water heading into fall.
- Sand filters: Backwash thoroughly, then treat with a sand filter cleaner to dissolve the oil and organic buildup that backwashing alone can’t remove. If your sand is more than five years old, August is a good time to evaluate whether it needs replacing before closing.
- Cartridge filters: Remove and soak cartridges overnight in a filter cleaning solution, not just a hose rinse. A properly cleaned cartridge filters at a fraction of the flow resistance of a clogged one.
- DE filters: Backwash, add fresh DE, and inspect the grids for tears or cracks. A torn grid lets unfiltered water bypass the media entirely — you won’t see the problem in your water clarity until it’s significant.
A clean filter going into the closing process also means less debris sealed under your winter cover, and a faster, easier start when you open in spring.
Rebalance Your Water as Temperatures Start to Shift
Late August brings something that catches pool owners off guard: the water starts to cool at night even when days are still hot. Temperature fluctuations affect your chemistry in ways that a single weekly test can miss. pH tends to rise in cooler water. Chlorine demand shifts. If you’ve been running on autopilot since June, it’s time for a full water test — not just a chlorine check.
Target these ranges heading into the back half of August:
- pH: 7.2–7.6. The lower end of this range maximizes chlorine effectiveness as temperatures begin to drop.
- Total alkalinity: 80–120 ppm. Alkalinity acts as a pH buffer — if it’s off, your pH will swing unpredictably.
- Calcium hardness: 180–220 ppm. Low calcium hardness causes water to leach calcium from your pool’s plaster or grout, leading to etching and surface damage over winter.
- Cyanuric acid (stabilizer): 30–50 ppm. If heavy summer rains have diluted your water, stabilizer levels may have dropped. Check and top up before the UV intensity of late summer burns through your chlorine.
Doheny’s pool chemicals section carries balancers for every parameter — pH Plus, pH Minus, alkalinity increaser, calcium hardness increaser, and stabilizer — along with test strips and digital testers to get an accurate baseline before you start adjusting.
Inspect Your Equipment While It’s Still Running
Equipment problems are always easier and cheaper to fix during the swim season than after closing. August gives you the advantage of being able to run everything and observe it under load. Walk through this inspection before the end of the month:
- Pump: Listen for grinding, rattling, or cavitation sounds. Check the pump basket for cracks. Verify the lid O-ring is pliable — a brittle O-ring will fail at the worst time.
- Filter pressure gauge: If the gauge reads high at clean startup, the gauge itself may be faulty. A broken pressure gauge leaves you flying blind on filter maintenance.
- Heater: If you use a gas or electric heater, run it for 20 minutes and verify it reaches temperature. Heater repairs in September take longer due to technician demand — finding a problem in August gives you time to fix it before closing.
- Skimmer baskets and weirs: Check for cracks or warping. Damaged skimmer weirs allow debris to fall back into the pool when the pump shuts off.
- Pool cleaner: Whether you run a robotic, suction, or pressure-side cleaner, inspect hoses, connections, and wheels or tracks for wear. If your cleaner is struggling with late-summer debris, see our Robotic vs. Suction vs. Pressure Pool Cleaners comparison to evaluate whether an upgrade makes sense before next season.
Order Your Closing Supplies Now — Not in October
This is the advice most pool owners ignore until it’s too late. Every September and early October, pool supply inventory gets picked over quickly as owners across the country realize they need pool closing kits at the same time. Shipping times stretch. Specific products go out of stock. You end up buying whatever’s left rather than what’s actually right for your pool.
August is the time to order closing supplies — while stock is full, prices haven’t shifted, and you have no deadline pressure. What you’ll need:
- A winter closing chemical kit sized for your pool’s gallonage
- Closing shock (calcium hypochlorite)
- Winter algaecide
- Winter cover (if yours is worn or cracked from last season)
- Air pillow for above-ground pools
- Winter plugs for return lines and skimmer openings
- A cover pump to remove standing water from the cover through winter
Doheny’s winter pool accessories section is one of the more complete sources I’ve found for closing supplies — they carry everything from basic plug kits to full winterization bundles, with free shipping on orders over $50. Ordering in August also gives you time to address any gaps in your kit before closing day actually arrives.
Shock Weekly Through the End of August
As swim season winds down, pool owners often start relaxing their shock schedule. That’s the wrong instinct. The last heavy weekends of summer — Labor Day gatherings, back-to-school swim parties — are some of the highest bather load events of the year. Shocking after each one keeps your water clean through the final stretch and, importantly, gives you a head start on the balanced, clear water you want going into the closing process.
A pool that’s shocked, balanced, and clean at closing holds its chemistry significantly better through winter than one that was closed with marginal water. Every dollar you spend on August maintenance is worth two dollars in spring opening chemicals.
August End-of-Season Checklist at a Glance
- Deep clean filter (sand, cartridge, or DE)
- Full water chemistry test — pH, alkalinity, calcium hardness, CYA, free chlorine
- Rebalance all parameters targeting the ranges above
- Inspect the pump, heater, filter gauge, skimmer baskets, and pool cleaner
- Shock after every heavy swim day through Labor Day
- Order winter closing supplies before the September inventory rush
- Note any equipment issues to schedule repairs before winterization
August is not the time to take your foot off the gas — it’s the time to use the swim season’s momentum to set yourself up for a clean closing and an easy opening next year. A few hours of attention now is worth far more than a weekend of emergency pool chemistry work when you pull the cover back in spring.