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Algae is the most common pool water problem only because it is the most visibly obvious one. Algae in itself is not dangerous — in fact, it is the main ingredient in many health supplements and tablets. Algae brings danger in that it converts sunlight into food, releasing wastes that become the feeding grounds for unwanted and harmful bacteria and other micro-organisms.

There are well over 20,000 species of algae, only a few of which are encountered in swimming pool water. Algae is almost constantly entering the pool, and as soon as the sanitizer level drops too low, the algae begins to take hold and multiply. It takes as little as a few hours on a warm sunny day for your sparkling pool to develop an algae problem. The algae "spores" found in the air are from algae that have dried out (at a nearby stream, from a neighbour's pool, etc.) and become airborne with the breeze.

Algae in swimming pools is often referred to by its color:

Green algae is the most common type of algae that you might find in your pool. As the name implies, green algae appears typically in various shades of green, but can also appear yellow-green and blue-green in color. Green algae floats and grows freely in the water, but also easily attaches itself to surfaces in the pool. What may feel like an unusually slippery surface may actually be a thin film of green algae growing on the surface. Green algae can also float in patches in areas where there is little to no water circulation. It can spread quickly across your pool, in rapid growth spurts called an algae bloom. 
These algae blooms are the result of exponential algae growth and multiply quickly in the right conditions. Left untreated, green algae overwhelms the typical chlorine sanitation rmethod in your pool. The algae growth will continue unchecked causing discolorations and staining of pool surfaces, and eventually clog water filters and putting a strain on pool pumps.

If you notice your pool water has a green hue, you may have small-celled green algae growing in the water. If your swimming pool water tests negative for metals like copper you likely have small-celled green algae growing in your pool. The water may appear clear or have a slightly hazy appearance with the distinction is that small-celled green algae makes the water look clear green.

Mustard algae gets its name from its yellow or yellow-orange color, and it is also called yellow algae. It is similar to green algae in consistency, although it can form in more coherent clumps, along with a dusty or powdered appearance on pool walls and floors. Yellow algae prefers shaded areas of the pool and should be the first place to look if you suspect you have an algae problem or live in areas prone to mustard algae growth. Typical places to look for yellow algae are behind ladders and under water slides, on the vertical faces of shaded stairs and near any decorative stone formations that block sunlight from entering areas of the pool.

Mustard algae spores are much smaller than most green algae, so they often pass through pool water filters, making it difficult to remove. It can come back easily and quickly without proper treatment. Mustard algae sticks to everything and can reform if you do not take everything out of the pool before treating it.

Black algae, also called blue-green algae, is the worst kind of algae for swimming pools, mainly due to its rugged ability to survive even after efforts to clean it from the infected pools. Early black algae formation is noted by small black dots on pool floors and walls or sides, often in shaded areas and areas with crevices, cracks, or imperfections in pool surfaces. They quickly grow to round, coin-sized patches, either in black or dark blue-green hues. Black algae grows in layers. The initial algae spores root themselves to the surface and into cracks and crevices. The successive outer layers coat and protect the layers beneath, ending with a waxy coating that makes it difficult to penetrate.

Black algae should be taken care of as soon as it become apparent as it is easy to identify in its early stages. Algaecides and shocking the pool have little effect on black algae growth. The interior surfaces of pool weirs are notorious for black algae growth as flowing pool water keeps the surfaces moist, yet the lid blocks out most of the light.

Although not actually an algae at all, pink algae is the result of bacteria growing in rapidly expanding colonies. The pink color is the result of pink or reddish color pigments in its cells. It has similar properties to algae and requires a similar treatment. It is heavier than water, so it tends to grow towards the bottom of swimming pools and away from sunlight. It has a slime coating which protects the bacteria colony and it can be very difficult to remove. Bacterium that grows into pink algae is found naturally and freely floating in the air and swimming pool water is constantly being bombarded. Prevention is the best measure to prevent pink algae from gaining a foothold. 

Cleaning algae can be an arduous task and does require some patience and precision, but is worth the time to ensure you can use your pool as often as you would like without incurring problems. Below are the general steps used to eliminate the various algae types discusses earlier.

  1. Scoop, vacuum and remove as much loose debris as possible in the water.This is to clear out as much organic material as possible to give the next step (shocking the pool) the maximum effect and give the shock the opportunity to focus on the contaminants you cannot remove with a net, including the algae. Do not brush yet, as you do not want more loose and alive algae growths floating freely in your pool water.
  2. Clean out all your filters. Make sure your pool can circulate the water as efficiently as possible by cleaning out all your baskets, as well as backwashing your sand filter.Your pool motor should be on and circulating the water.
  3. Shock the pool water. When shocking, use a shock product, following the package instructions or add granular chlorine to achieve 30 000 ppm or greater of chlorine. Apply the shock treatment after sunset - you want to avoid shocking the pool in sunlight, as the sun's UV raysquickly destroy the sanitation abilities of chlorine.
  4. Brush the pool surfaces. Brush all the walls and floors of the pool, even areas where you do not see the algae growth. The idea here is to break the bond the algae has with the pool surface to help the shock do a better job of fully surrounding each algae growth. An added benefit of brushing after adding shock is to keep the shock product moving around in the pool water. This reduces the time the shock sits on the pool bottom, potentially bleaching colored patterns in your pool floor.
  5. Let the pool shock do its job.Test the chlorine level later in the day if you used a chlorine-based shock. Test again twice per day until you see the chlorine drop to 3 ppm. At this point make sure you are resuming your normal sanitation routine.
  6. Add an algae-specific algaecide once per week.
  7. Once again clean out your pool baskets and backwash the sand filter.

Though this will not likely be the case for you, neglected pools resembling something that looks like a frog pond with extreme cases of algae may require you to enlist the help of a pool professional to drain and acid wash the pool shell. However, you want to minimize acid washes, as these are very hard on pool surfaces.

In conclusion, if your chlorine level is steady at 1-3 ppm, pH, total alkalinity are all balanced, your water is clear and you have no suspicious growths or discolorations on your pool walls or floors, then you likely have eliminated algae from your pool. As an added bonus, your water is now well-balanced, sanitised and ready for swimming.

If you have algae in your pool, don’t think that you have failed your duties as a pool maintainer. Most pool owners have problems with algae and most algae problems are not necessarily the owner's fault. Follow the steps above to prevent and treat pool algae problems. As with keeping other water balance levels in check, prevention is always easier, less costly and less stressful than correcting problems.

Preventing algae is as easy as just maintaining a healthy and balanced pool water environment. Take the following precautionary steps to ensure that algae formation does not occur in your pool:

You have multiple filtering mechanisms in your pool water filtration system - a sand filter, a pool pump basket and a weir basket. If these become blocked and choked, the amount of water passing through them decreases, which in turn decreases your pool water's circulation limiting the sand filter's ability to trap spores and thereby giving algae the opportunity to attach more easily to pool walls and surfaces.

Maintain a pool water pH level of between 7.4 and 7.6, and monitor the pH level often. Although keeping a pH-balanced pool still allows for algae to grow (algae grows between 6.5 and 12.5 pH), a proper pH level helps maintain the other water balance chemicals in your pool and enables chlorine to be most effective at sanitizing the water.

Brush the walls, floor, steps and any hard to reach places once a week. Brushing your swimming pool breaks up any algae formations attempting to make your pool their home and makes sanitizers like chlorine more effective. Look for any areas with cracks, crevices, or shaded areas in the pool and brush these areas thoroughly.

Keeping your chlorine levels at 2 ppm (parts-per-million) will ensure you have enough chlorine to either kill algae already growing in the pool, or keep the algae growth rate down between algaecide treatments to your pool water. Regularly test your pool water chlorine levels, up to once per day during the warm summer months and whenever you use the pool. The best thing you can do to give algae a chance to thrive in your pool is let your chlorine level drop to zero! With no sanitizer, there is nothing in your water stopping algae from growing in your pool. Algaecides do help, but they are only effective with the use of a sanitizer.

A salt chlorinator can help maintain pool water chlorine levels and kill algae before it forms. Simply put, a salt chlorinator (also known as a salt system or a salt chlorine generator) is a swimming pool chlorination system that creates chlorine from sodium chloride (salt). Before a salt chlorinator can operate, the swimming pool water must have a salt concentration of 3,000 ppm.

As salt water travels through the swimming pool’s circulation system, it enters the chlorinator and passes through a salt cell. As the salt water flows through the cell, a low-voltage direct current is applied to flat, rectangular plates inside the cell, initiating electrolysis Through electrolysis, salt and water break up into hydrogen gas and hypochlorous acid. The hydrogen gas simply leaves the swimming pool water in the form of small bubbles and the hypochlorous acid sanitizes the swimming pool water and ultimately reverts back into salt and the process repeats.

Salt chlorinators offer homeowners a wide array of benefits. Our customers love chlorinators because they eliminate the need for most swimming pool chemical maintenance (which translates to lower maintenance costs). For example, at the site of electrolysis (the salt cell), chlorine is so concentrated that the swimming pool water is superchlorinated, preventing the buildup of chloramines and algae. As another example, sanitizers have very low pH levels (some as low as 2.8), which can significantly lower the pH of a swimming pool. Homeowners who use sanitizers with very low pH levels must also use liberal amounts of sodium carbonate to offset the drop in pH. Salt chlorinators, on the other hand, require few, if any, additional chemicals, as they produce nearly neutral pH levels.

Other advantages of salt chlorine generators include: reduced skin and eye irritation, no harsh chemical odors, and swimmer safety.





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