So if the pool water isn't cloudy and the 'dirt' is clinging to the walls after brushing, the problem is likely be yellow/mustard algae. Yellow/ Mustard algae is very resistant to even high chlorine levels and will grow and thrive in a chemically well-balanced pool.
Black algae is a stubborn organism. Its protective outer layer sets roots into the surfaces it clings to. This makes it one of the toughest algae strains to get rid of.
Mustard algae tends to cling loosely to the walls of the pool and brushes off easily. It tends to have a yellowish color. Green algae will be visible throughout the water itself and will turn the water different shades of green depending on the infestation.
A natural way to get rid of green algae in the garden
If you are ready to put in some work, grab a stiff bristle brush and mix some dish soap, water and bicarbonate of soda. Once applied to patios and paving, give them a really good scrub.
Chlorine is still one of the most effective killers of algae so doing a super-chlorination of 10-20 ppm of chlorine can go a long way towards wiping out the algae. Liquid chlorine is an ideal shock for algae because it is fast acting and does not add cyanuric acid (CYA) or calcium to the water.
Hardware stores and home centers sell products designed to kill moss and algae, but you can save money by using inexpensive chlorine bleach or a non-creamy hand dishwashing detergent, such as Dawn.
In the same way that baking soda can be a spot treatment for black algae, household borax does the same for blue and green algae. Simply use the borax to scrub away algae that's sticking to your pool walls, then use the brush to dislodge it. Follow up by vacuuming up or scooping out the free-floating algae.
Yellow Algae (Mustard Algae) are a more chlorine-resistant type of algae that tends to form in the shade. Unlike green algae that grow better in sunlight, mustard algae grow in dark corners and walls, and form a yellowish-green layer that is pretty easy to brush off.
Use Tools to Manually Remove Algae
This gentle sponge is made of non-toxic melamine foam and won't scratch your glass and acrylic tanks. If you're having trouble scraping off very tough algae like green spot algae, try using a Mag-Float Glass Cleaner with the matching scraper blades.
There are a lot of reasons why algae keep returning to pools. The most common of these reasons are: Low levels of chlorine or chlorine getting burned up too fast before it gets the opportunity to kill the algae.
Adding shock to your pool super-chlorinates your water. And this extra dose of sanitizer will kill algae growth. The more serious your pool algae problem, the more shock you'll need. We recommend using calcium hypochlorite shock, or cal-hypo shock, as an effective algae treatment.
If the pH becomes too high (over 7.8), it prevents the chlorine from doing its job. If you're not checking the pH and it has risen too much, you could be adding the right amount of chlorine, but it can't work correctly, and algae will begin to grow.
Since baking soda is highly alkaline and reacts when mixed with an acid, many people assume it can be used to change the pH of a pond to discourage algae growth. However, even a large amount of baking soda dissolved in a pond will have little to no effect on either algae or pH.
Use White Vinegar to Remove Algae
If you have an algae problem, your best friend is white vinegar. White vinegar can quickly kill algae but is not harmful to birds, insects and the majority of plants. Use a mixture of one part water to one part white vinegar to spray down the area and kill the algae.
ATTENTION: Cyanobacteria blooms/HABs can produce toxins that are harmful to humans and animals. Cyanobacteria get their name from their blue-green pigment but blooms can often look green, blue-green, green-brown, or red. Algae and aquatic plants are usually green but can appear yellow or brown as they die down.
A close relative to green algae, mustard algae can be yellowish, yellow-green or brown in color and is typically slimy. Commonly mistaken for dirt or sand, mustard algae will persistently cling to pool surfaces, light fixtures, wall fittings, ladders and other items, like toys or bathing suits.
Other Ways to Recognize Black Algae in Your Pool
It is attached to rough surfaces and will not freely float in the water. It will not come off the wall easily with a pool brush or vacuum. If you manage to scrape it off the wall, it will likely return time and time again without proper removal.
Combining vinegar, water and baking soda is ideal for targeting the toughest algae stains and mould growth. In a large container, add two parts white vinegar to one part water and stir in three heaped teaspoons of baking soda.
Q Here in the Pacific Northwest, one solution I have found effective in the removal of algae from our brick patio is to spray the surface with apple cider vinegar. I use a pump sprayer early in the spring on a dry day, and it lasts the entire year. The vinegar smells for a short time, but leaves nothing to wash off.
Yes, dilute apple cider vinegar (ACV) is a great choice for combatting algae in your bird bath the natural way. The higher pH value of the ACV makes it too acidic for algae to grow.