Got Yellow Algae in Your Pool? Here’s Why

If the water in your pool appears more yellow than a sunset, then its possible you have yellow algae (which TFP calls mustard algae). Yellow or mustard algae is a tough and chlorine resistant issue that can attach to surfaces (especially in shaded spots). Unlike green algae, yellow algae attach to surfaces instead of floating in the water. Even if the pool water looks clear, yellow algae will cause your pool to be unpleasant.

Regular chlorine treatments won’t be enough if your pool is yellow; you’ll need to scrub the surfaces and use a special algae-killer to fully get rid of the problem.

What causes yellow algae?

Yellow algae can grow in pools when there is not enough filtration and not enough chlorine. Many things can affect filtration and chlorine levels. These include:

Pump speed

How long the pump runs

Cleaning methods

Number of swimmers

And even the weather.

Yellow algae love heat, especially in the summer months, so if you’re in a warmer climate such as Arizona, Texas, Florida, or elsewhere your pool is more susceptible to it during the summer months. They are most fond of dark environments and attach themselves to walls and floors where sunlight can’t reach them, making them hard to spot before they have become widespread.

Another contributor is chlorine: Yellow algae can spread very quickly when there is not enough chlorine in the water because of heavy use of the pool or skipped maintenance. Bad circulation can also contribute; for instance, if the pump isn’t running long enough or the filter is dirty, it can stagnate, and that gives algae a great chance to grow.

Finally, cross-contamination has an impact as well, they can hitch a ride on swimsuits, toys, pets, or pool tools that were used somewhere else. So, for this reason a good practice is always to rinse anything that is about to go in your pool.

How do you get rid of yellow algae in a pool?

Now that you know what yellow algae is and what causes it, how do you get rid of it? Here are some tips:

Step 1: Brush it Off: The first step in your yellow algae eviction mission is a good old scrub. Grab a brush suitable for your pool surface and vigorously scrub the walls and floor. This disrupts the algae’s hold, making it easier for chemicals to do their job.

Step 2: Shock and Awe: Then you’re going to give the algae a shock treatment. Use a good quality pool shock and follow the directions exactly. You are looking for a really high chlorine level to break down the thick, defensive layer algae build up.

Step 3: Let it Circulate: Run the pump non-stop for a minimum of 24 hours after shocking to keep everything circulating and getting to all the tight nooks and crannies. Be sure to clean or backwash your filter to remove the dead algae pieces afterward.

Step 4: Algaecide Attack: Follow up the shock treatment with a mustard algaecide. These specialized formulas are designed to target yellow algae effectively. Add the algaecide according to the packaging and continue running your pump for another 24 hours.

Step 5: Balance and Maintain: Once you’ve given the algae the boot, it’s time to balance your pool’s chemistry. A good tip by Arm & Hameer is that you need to check the pH, alkalinity, and calcium hardness levels to make sure everything is in harmony.

Pro Tip: To keep yellow algae from becoming an issue later on, it’s important to set up a regular maintenance plan.

Tips to maintain a clean pool and getting rid of yellow algae

Scrub and Vacuum Often: Brush the walls and vacuum the floor of your pool on a weekly basis to remove spores before they have settled.
Test Chlorine Levels: Test the chlorine levels of your pool regularly and after any social gatherings or heavy rains. If needed make appropriate changes to the water levels.
Ensure Proper Circulation: Keep your pump running on high for 8-12 hours a day to ensure the water is filtered and treated chemically throughout the entire pool.
Make Shocking a Routine: Make shocking your pool a regular commitment. Pools get shocking after high usage counts or during hotter months.
Rinse All Pool Items: Rinse your swimsuits, pool toys, and other equipment off before using them in your pool. The slightest precautions can protect you from a major problem.

FAQ's

1. What causes yellow algae in pool?

Yellow algae, or mustard algae, pop up mostly when the water’s not moving enough, the chlorine’s all over the place, it’s warm, and there’s not enough sunlight in the pool. Things like swimsuits or toys getting mixed up with the water, or not keeping the pool clean enough, can also cause and spread that yellow algae in your pool.

2. Where does yellow algae come from?

Yellow algae spores can sneak into your pool through stuff like dirty swimsuits, toys, or even your pets. They love it warm and cozy, especially in the shady spots by the pool where the sun can’t touch them, so they’re kinda sneaky and spread out a lot before you notice.

3. How to prevent yellow algae in pool?

To prevent yellow algae in your pool, establish a consistent maintenance routine that includes: Regular brushing and vacuuming of the pool surfaces Maintaining proper chlorine levels Ensuring optimal water circulation by running the pump 8–12 hours daily Shocking the pool periodically Rinsing pool gear before use

4. Why doesn’t regular chlorine kill yellow algae?

Yellow algae have this special coating that helps them stand up to regular chlorine without getting damaged. That’s why the usual ways don’t always work out to get rid of them, you usually need to call a pool professional.

5. How do I spot those yellow algae in my pool?

Yellow algae, those annoying little guys, tend to show up as a yellow or mustard-colored dust on the pool walls and floor, especially where the sun doesn’t shine too much. It might look like pollen but it’s not going to fall off easily. If your pool water’s all murky and there are these annoying yellow spots sticking around, it’s probably yellow algae causing the trouble.