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A Step-by-Step Guide on How to Clean a Green Swimming Pool

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From keeping koi carp healthy to running a swimming pool for over 20 years, I understand the importance of looking after your water.

Prevention tip: We take a net in the pool every time we swim just to take out any material that has fallen in.

Prevention tip: We take a net in the pool every time we swim just to take out any material that has fallen in.

Keep Your Swimming Pool Algae-Free

When you own your own swimming pool, the aim is to have crystal clear water. Unfortunately, this is not always the case!

During a daily inspection, you might notice that the pool has slightly cloudy water or a little algae growth. If you have been away from your pool for a few days or weeks, then you'll probably return to see it full of algae.

I hope this article will help you manage any water clarity issues, fix a green or cloudy pool, and prevent any future problems.

How to Manage Your Pool on a Daily Basis

The best way to enjoy a crystal-clear pool is to manage it on a daily basis. Just spending 10 minutes per day is all it takes.

  1. Every morning, I check for signs of algae growth or cloudiness in the water. If there are signs of algae growth, I start by sweeping away the growth. I also net out leaves and insects on a daily basis.
  2. I check the chlorine levels and make any adjustments to the water when required.
  3. It is also good practice to check the skimmer nets each morning. Remove any vegetation that has collected or any insects that have perished during the night.
  4. If the water looks a little cloudy, try backwashing your sand filter for a few minutes and see how the pool looks the next day.
  5. Also, check the pH of your pool to make sure any chemicals you are using are functioning as they should.
  6. The ideal pH level for a pool should be between 7.2 and 7.6. If your readings are out of this range, then you need to make adjustments to the pH of your water so that treatments will function properly once added.

How to Make a Green Pool Clear in a Few Simple Steps

If I ever go away for a week during the open season, I run the risk of returning to a green pool because the daily maintenance procedures do not take place. The risk is increased if I leave the pool covered with its summer "bubble wrap" cover, which creates a greenhouse for the algae to thrive.

Make a Green Pool Clear in 24 Hours

  1. Net out any debris that you can see within the pool.
  2. Clean out your skimmers and put in new nets.
  3. Brush all the walls and the floor of the pool to remove the algae from the pool liner.
  4. Clean the built-in pump filter.
  5. Backwash your sand filter for a couple of minutes. (Once cleaned, your filtration system should work at the maximum flow rate and can now tackle water problems more efficiently.)
  6. Check the pH level of your water to make sure it is at the correct level. This is important because in order for any chemicals to work properly, the pH level must be correct. If the pH level is not correct, make the necessary adjustments before moving on to the next step.
  7. Add sufficient chlorine to the pool as a shock treatment. Follow the instructions on your particular product, and make sure to calculate for the size of your pool.
  8. Place flocculant into one of the skimmer baskets. This product is designed to bind smaller particles within the water into larger particles so that they can easily be trapped within the sand filter.
  9. Backwash your sand filter again after 12 hours and replace skimmer nets if clogged with algae.

After running the filter system for 24 hours, the pool will be totally clear of any living algae, and you will just need to hoover up any dead material found at the bottom.

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How to Backwash a Sand Filter

On the top of my sand filter, there is a dial to adjust the direction of the water flow through the system.

  1. Before making any adjustments to the dial, it is important to switch off the pump.
  2. Once the pump is off, just move the dial to backwash, close the valve so the water can return to the pool, and open the other valve to allow the water to be emptied via the sand filter.
  3. Switch on the pump. The water flow through the sand filter should reverse in order to clean all the dirt within the sand. This dirty water is drained out of the system without entering the pool.
  4. On my sand filter, I have a small glass-viewing bulb that allows me to view the water exiting the filter. When you first turn the dial to backwash, you can see that the water is very cloudy, but after just 2 minutes, the water is clear again. At this point, the sand filter is clean.
  5. Switch off the pump.
  6. Change the dial back to normal operation.
  7. Close the valve that allows the water to exit the system and re-open the valve that allows the water to flow back into the pool.
  8. Restart the pump, and the job is complete.

Note: If you do not run the backwash long enough, then any dirty water within the sand filter will be pumped back into your pool once you restart the pump.

When to Empty Your Green Pool and Start Over

If the pool is so green that you cannot see your hand when you submerge it in the water, then the best option would be to empty the pool and start over. You might worry about the cost of replacing all of the water, but you could end up spending a small fortune on treatments only to empty the pool in the end because the treatments failed.

I would recommend taking a water sample to be tested at your local pool shop. It might show that your pool is full of stabilizer. Cyanuric acid (stabilizer) is added to chlorine tablets to prevent the chlorine from being eaten away by the sun's ultraviolet rays. Every time you add chlorine tablets to your pool, you're adding additional stabilizer. Unlike chlorine, which evaporates over time, the stabilizer remains.

If your pool contains too much stabilizer, it inhibits the chlorine from sanitizing the water, thus making the chlorine useless.

The only way to reduce the stabilizer is to introduce fresh water. So, in the end, the final solution is to pump out 80% of the water from the pool and start afresh. In France, public pools are emptied twice a year for this very reason.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

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