Green Algae Is Common But What About Other Colors?
Algae typically occurs in pool due to a lack of chlorine and improper filtration. Normally a properly chlorinated pool is enough to keep algae at bay. Algae can enter the pool from rain, wind and other sources but normally the chlorinated water won’t allow it to grow.
Other than keeping water chemistry in order, the best way to prevent algae growth is to regularly brush the walls and floor of the pool and then vacuum it. Rinse or backwash the filter as needed and more frequently if you have an algae outbreak.
In my experience, significant algae in your pool really clogs the filter to the point where I’ve been vacuuming the algae out of the pool and can actually see greenish water coming back into the pool through the water return jets. This typically means the filter is full and can’t hold any more of the algae and needs to be rinsed or backwashed, depending on what kind of pool filter you have.
I wrote an entire post on green algae since it tends to be the one many pool owners will face from time time, myself included.
If you have mustard or black algae in saltwater pool, why does it occur and how can you get rid of it?
What Causes Yellow Algae In A Swimming Pool?
Yellow algae is caused by the same things that cause green algae in a saltwater pool:
- Lack of chlorine
- Lack of proper pool filtration
Yellow or mustard algae is yellowish as the name would suggest and like green algae, is difficult to get rid of with just chlorine. It tends to have a cloudy look and if you swish the water around it dissipates and floats away like dust. Green algae is slimy and you can wipe it off with your hand, although I wouldn’t necessarily suggest that. Wear gloves if cleaning algae manually just to be safe.
Mustard algae tends to appear in hotter southern locales than in colder northern environments, too.
How To Get Rid Of Yellow Algae
I’ve already written about how to get rid of green algae, what causes it and how to avoid it. The steps to get rid of yellow or mustard algae are similar. To summarize:
- Check pool chemistry and get it right. In all likelihood chlorine is low.
- Take a look at the filter to see if it needs to be rinsed (cartridge filter) or backwashed (sand filter).
- Brush the entire pool including walls and pool floor.
- Vacuum the entire pool.
- Rinse or backwash the filter depending on which type you have.
- Add an algaecide to the pool and let it do its thing for a day with the pump running.
- Vacuum the pool again to get rid of the remaining algae.
- Rinse or backwash the filter again.
- Repeat steps if necessary.
Also remove anything that was in the pool such as toys, noodles etc and clean them well. Also ensure anyone using the pool washes their swimming clothes to ensure they have no algae.
Removing algae completely in my experience will take at least a few days, with multiple treatments possibly required.
What Causes Black Algae In Saltwater Pool Water?
Black algae tends to appear as small groups of dots in the pool particularly on concrete areas in between cracks. It looks like mold to the naked eye. It tends not to appear in either fiberglass or vinyl liner pools but rather other surfaces like gunite, plaster and the aforementioned concrete since those surfaces are hard and porous and allow the black algae to attach to and grow.
Black algae may have entered your pool through the air as other types of algae. But it can also enter your pool from dirty swimwear that was recently worn in a river or lake with black algae but not washed before entering your pool.
So to avoid black algae in the future, make sure you properly wash any swimming clothes that you used in other bodies of water but especially natural ones like rivers, lakes and the ocean.
Unlike green or yellow algae, black algae sticks to the pool’s surface and isn’t necessarily easily removed. So we need a slightly different method to do so.
How To Get Rid Of Black Algae
Since black algae is more difficult to get rid of, here’s how to do it:
- Check pool chemistry and get it right. Make sure all readings are in line and double check that chlorine is within range.
- Brush the entire pool including walls and pool floor but focus on the areas that have the black algae. If it’s a vinyl or fiberglass pool use your pool brush but if you have a concrete pool, you’ll need a stronger wire brush to loosen the algae.
- Vacuum the entire pool.
- Rinse or backwash the filter depending on which type you have. If you have a cartridge filter like we do and it’s a few years old, you may consider replacing it in case black algae has grown there too.
- Use a black algae-specific algaecide such as Leslie’s Black Algae Killer or Suncoast Chemicals Super Black Algaecide and follow the instructions to add to the pool.
- Vacuum the pool again to get rid of remaining loose algae.
- Rinse or backwash the filter again.
- Repeat steps if necessary.
If you have chlorine tablets on hand, you might also consider putting gloves on and going to areas that are reachable, that still have black algae and rub a chlorine tablet directly onto the remaining black algae. This will help to start killing the algae. Then scrub again to try to remove it.
As with yellow algae, you might need to repeat the steps and keeping an all in one algaecide product on hand to quickly deal with future algae outbreaks isn’t a bad idea either.
Conclusion
- Mustard algae tends to occur in a saltwater pools for the same reason that green algae does: lack of proper water filtration and lack of chlorine.
- Black algae tends to occur in concrete pools rather than fiberglass or vinyl liner pools and is often more difficult to get rid of. It may be airborne or introduced through contaminated swimming clothing previously worn in a lake or river.
- As with other algae cases, keep your pool pump running constantly while the problem is being solved so that water is being filtered, algaecide is moving throughout the pool and chlorine is being produced.
- The quicker you can deal with any algae problem, the quicker you can get rid of it before the algae really has a chance to bloom.