- First, you should know that not all green pools are dirty. Many times the problem is simply a lack of chlorine in the water. You'll want to add bleach or pool shock with high available chlorine levels (at least 30 ppm) if this is your case. After doing so, take an algae scraper and remove any visible growths from surfaces inside and around the pool (e.g., walls). Then brush off anything stuck on tiles - they will probably need a good scrubbing after being exposed to harsh chemicals like those found in bleach!

You can also use algaecide products designed for swimming pools containing metal halides which act as powerful inhibitors for plant life such as grass, leaves, etc. However, you must read the label and apply it as instructed.

Any other type of green growth is best treated with a triple-whammy approach: shock, algaecide, and chlorine tablets or bleach (as mentioned above). Will ensure your pool gets back to its normal self in no time! Finally, check for leaks by using a water test kit from any major retailer like Walmart or Home Depot. You'll be amazed at how much water can escape unnoticed over time.

Unfortunately, not all pools will get clear right away, even if you do what we just recommended here. If you still see algae growing inside your swimming pool after following this guide, don't worry because there is something else to try before throwing in the towel.

Your cartridge filter might need a replacement if it is really dirty, as algae is most likely growing in the pores of your sand or DE filters. If you don't have an extra one lying around at home, then consider buying another swimming pool cleaner online for cheap and swapping out cartridges so they can both be cleaned properly (e.g., soak them overnight). Just make sure to remove any debris that comes through during this process to avoid clogging up the new filter!

If all else fails, there's nothing wrong with bringing in professional help from someone who specializes in green pools - try finding reviews on their services first before deciding which company to trust.

In short:

- Test chlorine because sometimes water isn't green, and it's just a lack of chlorine

- Use algaecide, shock the pool, and add chlorine tablets or bleach to kill green growths

- If algae still grow after this approach, you might need a new cartridge filter or professional help!