Finding algae growing under your pool liner can be worrying, but have no fear – with the right approach, you can get rid of it for good. As your pool maintenance buddy, I‘m here to walk you through this step-by-step so you can get back to enjoying clear, algae-free water.
What‘s Causing That Icky Algae?
Before we dive in on removal, it helps to understand what allows algae to thrive in the first place. Here are the top culprits:
Insufficient Chlorine
Chlorine is your number one defense against algae, bacteria and other icky stuff. When chlorine drops below 1-3 ppm, it opens the door for algae spores floating in the water to germinate and spread. I recommend testing chlorine 2-3 times per week to stay on top of levels.
Improper pH
pH indicates how acidic or basic your pool water is. For chlorine to work its magic, pH must be 7.2-7.8. A pH higher than 7.8 makes chlorine essentially useless against algae. Check it at least weekly and adjust as needed.
Poor Circulation
Letting water stagnate allows algae to flourish. Ensure water circulates everywhere and run filters for at least 8 hours daily. Check for and remove any debris trapping water.
High Nutrient Levels
Phosphates and nitrogen compounds act like fertilizer, feeding algae growth. Runoff from lawns, gardens and other sources introduces these nutrients. Check phosphate level and use a phosphate remover if over 30 ppb.
Sunlight Exposure
Like plants, algae needs sunlight to photosynthesize and thrive. Areas where sunlight directly contacts the liner are susceptible, especially slip-resistant steps and benches. Treat these areas with algaecide monthly.
Warm Water Temperature
Algae reproduces more quickly as water temperature rises above 70°F. Run your pump and filter at night to mix in cooler water and limit algae-friendly hot spots.
Now let‘s get down to tackling that algae!
Step 1: Test and Balance Chemicals
Before attacking algae with chlorine or algaecide, we need to ensure your water chemistry is balanced. Test strip kits from the local pool store make this a breeze.
Ideal water chemistry levels are:
- Free Chlorine: 1-3 ppm
- pH: 7.2-7.8
- Total Alkalinity: 80-120 ppm
Add chlorine or pH adjuster as needed until levels are right on target. Give the chemicals an hour or two to properly mix and distribute before moving onto the next steps.
Step 2: Shock That Algae Into Submission
Shocking the pool with a high dose of chlorine deals a devastating blow to algae. The best shock for tackling algae is calcium hypochlorite. Here‘s how to shock like a pro:
- Start with clean filter cartridges to maximize effectiveness.
- Dissolve the recommended dose in a bucket (saves your pool equipment from chlorine buildup).
- Spread the dissolved shock around the edge of your pool. Try to get full distribution.
- Run filter all night to circulate the chlorine through every nook and cranny.
- Test chlorine level the next day. Still below 5 ppm? Follow up with another shock treatment.
- Wait until chlorine drops back to normal levels before swimming again.
Repeat shock treatments may be needed for stubborn growth. Persistence pays off!
Shocking Tip: For a 20,000 gallon pool, use 9-15 pounds of shock containing at least 73% available chlorine.
Step 3: Brush Off That Gunk
Now it‘s time to get hands-on! Manual scrubbing removes the algae so it doesn’t keep spreading or re-root itself.
Use a stiff pool brush to vigorously scrub floor and walls where algae has taken hold. Focus on the really slimy lubricated parts like steps and benches.
Pro Tip: Switch to a soft nylon algae brush to tackle leftover sticky or fuzzy gunk the main brush misses.
Don‘t be afraid to really put some elbow grease into it – scubbing the gunk away is key!
Step 4: Suck Away The Scum
Vacuuming is the next critical step. This removes the scrubbed-off algae so it doesn‘t resettle and trigger regrowth.
You have two options here:
- Manual vacuuming – Use quick scrubbing motions and make multiple passes to pick up all debris.
- Automatic cleaner – Set to waste mode to discharge debris directly out of the pool.
For both methods, avoid sending debris directly into your main drain!
Step 5: Apply Algaecide For Prevention
After vacuuming up the algae, now you can apply an algaecide. The metals or quaternary ammonium compounds in algaecides provide lasting prevention between treatments.
Follow the product instructions for dosage and scheduling based on your pool size. Apply around the perimeter of the pool near returns for even dispersion.
Copper based algaecides work especially well if algae has been a frequent battle.
Step 6: Drain and Clean If Needed
In severe algae cases, it may be necessary to drain some or all of the water to fully remove all traces. This can jumpstart the cleaning process.
Before refilling, be sure to thoroughly scrub walls and floor with a stiff brush to remove any remaining algae. The fresh water will help disrupt the algae lifecycle.
Maintaining That Crystal Clear Water
Now that you‘ve won the battle against algae, let‘s ensure it stays away for good! Keep doing these tasks and you‘ll be lounging by pristine water all season long:
- Test and adjust chlorine & pH 2-3 times per week – Consistent levels are key!
- Shock weekly – Even if chlorine tests ok, shocking maintains a clean, algae-free pool.
- Check phosphate and treat if needed – Reducing phosphates starves algae.
- Clean filter regularly – Clogged filters reduce circulation and water quality.
- Brush & vacuum weekly – Remove debris and potential "algae food" before it attaches and grows.
- Apply preventive algaecide monthly
- Reduce heater run times – Lower water temperature slows algae reproduction.
Stay vigilant, test often, and don‘t give algae a foothold! Let me know if any other pool questions come up. Enjoy your sparkling clean water!
FAQs: Pool Liners & Algae
Still have some burning questions? Here I‘ll tackle some of the most common liner and algae issues pool owners face:
Can algae damage my liner?
Left uncontrolled, certain types of algae can degrade vinyl liners by secreting corrosive organic acids as they grow. The accumulation of sticky biofilm and slime buildup can also abrade and stain the liner. Keeping your chemicals balanced prevents algae from getting to this damaging stage.
Why does my liner look green?
Greenish discoloration or staining of vinyl liner material is typically caused by metals, especially copper, accumulating on the surface. Metals provide nutrients that feed algae growth. Using a sequestering agent to bind metals can help, along with maintaining proper sanitization and pH to prevent algae proliferation.
How do I remove green algae from my pool floor?
Green cottony or slimy material on floor indicates algae growth. Test and adjust chlorine to 1-3 ppm and pH to 7.2-7.8 first. Next, scrub the affected areas with a stiff brush, then vacuum debris away. Applying an algaecide after will help prevent regrowth. Stay vigilant with weekly brushing and vacuuming.
Is it safe to swim with algae in my pool?
Visibly contaminated water should not be swam in. Algae growth indicates chemical parameters like chlorine and pH are off-balance and need adjustment. The slick, slimy texture algae causes can also increase drowning risk due to loss of traction. Always treat and remove algae fully before allowing swimmers back in the water.
How long do pool liners last?
On average, vinyl pool liners last anywhere from 5-10 years before needing replacement. Factors like maintenance, bather load, and exposure to sun, chemicals and debris impact longevity. More frequent liner replacement every 3-5 years may be needed for pools in harsher climates or with recurrent algae issues.
How much does it cost to replace a vinyl pool liner?
Nationally, costs average $3,000-$5,000 to replace a typical 20×40 in-ground vinyl liner, including materials and professional installation. Upgrades like thicker gauge vinyl or tile banding can range $5,000-$8,000. Regional labor rates also impact pricing. Always get multiple quotes to find the best value.
Can I close my pool with algae in it?
Closing a pool that has not been fully treated for algae is never recommended. The warm, moist environment under the cover provides the perfect conditions for rapid spread of algae and bacteria. This can lead to a huge slimy mess requiring extensive remediation when reopening next season. Always eliminate algae and balance chemicals before closing.
You‘ve got this! With the right maintenance strategy, algae doesn‘t stand a chance. Let me know if you have any other pool care questions come up. Enjoy the rest of your swim season!
