Having a green pool can be frustrating. You’ve shocked it, waited the required amount of time, and it’s still green. Should you shock it again? Let’s take a look at some quick answers to common questions about green pools and shocking:
What causes a green pool?
A green pool is caused by algae. There are a few different types of algae that can make your pool water turn green:
- Green algae – This is the most common type. It’s actually a single-celled plant that spreads rapidly in warm, stagnant water that contains nutrients.
- Mustard algae – Also known as yellow algae, this type thrives in salty water and is most common in coastal areas.
- Black algae – The toughest to get rid of, black algae can form dark spots on floors, walls, and vinyl liners.
How do I get rid of green pool algae?
Shocking the pool with chlorine or an algaecide is the most effective way to kill off algae and clear up green water. The best process is:
- Test and balance the water’s pH and alkalinity.
- Shock the pool with a high dose of shock treatment (1-2 lbs per 10,000 gallons).
- Run the filter continuously for 24-48 hours.
- Vacuum and brush the pool to remove dead algae.
- Repeat shock treatment in 5-7 days if the water is still green.
- Maintain proper chlorine levels (1-3 ppm) to prevent algae from returning.
Shocking works by releasing a high concentration of chlorine or other algaecide into the water to kill the algae. However, it often takes more than one shock treatment if the algae growth was severe.
How long should I wait between shock treatments?
It’s recommended to wait 5-7 days between shock treatments for full effectiveness. Here’s why:
- Gives the first shock time to fully penetrate and kill the algae.
- Prevents over-chlorination from too much shock at once.
- Lets filters operate better by reducing chemical interference.
- Allows any dead algae to be cleaned out between treatments.
Shocking too soon wastes product. The chlorine from the first shock needs time to dissipate and finish the job of clearing up the water.
What if it’s still green after 2 shock treatments?
If your pool is still green after 2 proper shock treatments (correct dosage, 24-48 hours filtration, 5-7 days apart), a few things could be going on:
- Improper water balance – Unbalanced pH, alkalinity, or calcium can reduce chlorine effectiveness.
- Too much phosphate or nitrogen – Fertilizers or other contaminants can feed algae growth.
- Needs flocculant – A chemical like aluminum sulfate clusters particles for better filtering.
- Pump issues – Poor circulation prevents equal chlorine distribution.
- High demand – Heavy bather load, debris, and other factors may require more chlorine.
Testing the water and addressing any issues with your pool maintenance can help the shock work better. You may also need to switch to a stronger algaecide if green algae is especially stubborn. Calling a pool professional for service may be needed for tough algae cases.
Can I shock my pool multiple times in a row?
It’s not generally recommended to shock your pool more than once in a 5-7 day period. Repeated shocks can raise chlorine to unsafe levels and put strain on your pool’s components.
However, in severe cases of green algae, a pool pro may determine it’s ok to “super shock” 2-3 days in a row at a lower dosage (around half normal shock amount). This blasts the algae without overloading the water.
Test strips can help monitor chlorine levels if doing back-to-back shocks. And reduce the pump running time to 4-6 hours after multiple shocks to avoid equipment damage. Let chlorine dissipate 5-7 days before shocking again.
What are the signs I used too much shock?
Using too much shock at once or shocking too frequently can result in over-chlorination. Here are some signs you’ve overdone the shock treatments:
- Chlorine level over 5 ppm
- Strong chemical odor
- Cloudy water
- Skin/eye irritation
- Damage to pool surfaces
- Degraded vinyl, plaster, or tile
- Algae still present
If you see these issues after shocking, discontinue use and wait 5-7 days before shocking again at a lower dose. Over-shocking can be counterproductive, so it’s important to maintain proper chlorine levels.
How often should I shock my pool?
Regular shock treatments are essential for crystal clear water and preventing algae. Here are some general shocking guidelines based on pool use:
| Pool Use | Shock Frequency |
|---|---|
| Light (1-2 hours/day) | Every 2 weeks |
| Moderate (3-5 hours/day) | Weekly |
| Heavy (5+ hours/day) | 2-3 times per week |
Do extra shocks after heavy rain, bather loads, debris accumulation, or cloudy water. And always shock after algae appears. Maintaining proper chlorine and balancing water chemistry is also key for reducing the need to shock as often.
How do I maintain chlorine after shocking?
Shocking provides a chlorine boost to kill algae and contaminants. But you need to maintain a proper residual level after shocking too. Here are some tips:
- Test water 2-3 times per week and adjust chlorine to 1-3 ppm.
- Run filtrations systems enough daily for full water turnover.
- Use chlorine tablets in the skimmer if not using an automatic feeder.
- Add liquid or granular chlorine as needed to maintain proper levels.
- Shock weekly or as needed to restore free chlorine levels.
Having an accurate test kit is key to monitoring your chlorine residuals. Never let it drop below 1 ppm. And shock whenever chlorine drops below half the ideal level. Proper chlorine maintenance prevents algae regrowth between shocks.
Can too much shocking damage my pool?
Yes, overusing pool shock can damage surfaces and equipment. Here are some potential issues:
- Etching or discoloration of plaster
- Degradation of vinyl liners
- Corrosion of metal components
- Destruction of gaskets and seals
- Damage to automatic cleaners
- Cloudy water from chemical buildup
To avoid problems, carefully follow dosing instructions on shock products and test chlorine levels regularly when doing multiple treatments. Also run pumps and filters the minimum time needed after shocking. Fix any leaks and cracks that can allow condensation and chemical contact.
What if it’s still green after shocking and vacuuming?
If your pool is still green after properly shocking, running filters, and vacuuming out dead algae, the issue may require additional troubleshooting:
- Have a water sample analyzed at a pool store
- Check filter media and backwash if needed
- Clean out baskets and skimmer thoroughly
- Adjust pH, alkalinity, and calcium if off
- Add an algaecide like polyquat for tougher algae
- Use a flocculant to bond algae for better removal
- Increase chlorine to shock level and maintain it
- Run pump and filter 24 hours until clear
You may also need to identify and address the underlying cause, like high phosphates, low circulation, or contamination feeding the algae. Call a pool pro for advanced diagnostics and treatments if you can’t get rid of stubborn green algae.
Can I vacuum to waste after shocking?
Vacuuming to waste is an excellent way to remove dead algae after shocking your pool. When set to “waste,” the vacuum bypass the filter and pumps debris right out, reducing chemical interference and load on the filter.
However, you don’t want to waste too much water. So only vacuum to waste for the first hour after shocking. Then reset the valve to recirculate the water through the filter and continue vacuuming as needed to completely clean the pool.
Vacuuming to waste works best after using a clarifier or flocculant to bond all the particles together for thorough removal. Your pool water will be nice and clear after a good post-shock vacuuming session.
Is it safe to swim after shocking?
While swimming immediately after shocking is not recommended, in most cases it is safe to swim in a shocked pool after a reasonable wait time, such as:
- 2-4 hours if shocking at dusk or overnight.
- Next day if shocking in the morning.
- 4-6 hours with heavy shocking or during hot weather.
Test strips make it easy to check the chlorine level before swimming. Ideally, wait until chlorine is below 5 ppm. Also watch out for eye irritation, skin drying, or chemical odor as signs to give it more time.
Limit swims to 30 minutes and shower afterward if chlorine measures on the high side. While shocking makes swimming safe by killing pathogens, you want to avoid exposure to very elevated levels.
Can I shock my pool in the rain?
You can still shock your pool when it’s raining – the chemicals will work just fine. However, heavy rain can dilute the shock’s effectiveness. Here are some tips for shocking in the rain:
- Add 25-50% extra shock since some will dissipate from water dilution.
- Shock early in the day to allow time before possible rain.
- Shock after the rain stops so it doesn’t get immediately washed away.
- Test and monitor chlorine levels closely.
- Wait 5-7 days and re-shock if needed to maintain proper levels.
A dose of liquid chlorine alternative daily can also help maintain chlorine levels with heavy rain. Just take care not to over-chlorinate. Allow the rain to dissipate before swimming when high chlorine is suspected.
Should I shock my pool at night?
Shocking your pool at night offers some advantages:
- Lower evaporation so more shock stays in the water.
- Cooler water prevents rapid chlorine dissipation.
- No swimmers present to bother.
- Long contact time for the shock to work.
However, there are also benefits to shocking in the day:
- Easier to monitor effects and test levels.
- Can confirm there are no issues with equipment.
- Vacuuming out debris is more convenient.
- Easier to prevent pets or children from swimming.
So the ideal approach is to balance both times:
- Add shock in the evening 2-3 times per week.
- Do occasional daytime shocks to check equipment function.
- Vacuum and test water in daylight after shocking.
This ensures you get the maximum performance from the chemicals while still keeping up with pool maintenance needs.
Conclusion
Having to shock your pool multiple times can be an exercise in patience. But proper shocking is crucial for destroying algae and clarifying green water issues. Make sure to test water chemistry, clean debris between treatments, and maintain chlorine levels for the best results. If the pool is still green after several attempts, reach out to a pool pro for troubleshooting assistance. Consistent shocking and good water balance will pay off with a sparkling clean pool all season long.
