Algae: The plague of the pool owner


There are thousands of different kinds of algae and many may find a nice home in your pool.
Algae are single celled plants. For something so small to make your pool look so green, it take millions of plants.  The cause of all algae growth is the same.  Insufficient chlorination.  Once algae begin to grow there is a virtual explosion of new life.  Algae is easy enough to control with the proper attention to water chemistry. Pure-Chem specializes in balancing your pool's water chemistry.

The common types of algae in swimming pools are

"Green" "Mustard" and "Black"

"Green" algae is what makes your pool look like a pond.  It’s free floating and when you get enough of it you won’t be able to see the bottom of your pool.  It will clog your filter and make your life miserable.  Applying a sufficient dose of chlorine easily kills green algae. 

Chlorine is the best algaecide there is. There are lots of products on the market designed to kill algae.  All of them will work but they all cost more than chlorine and none of them are as effective. 

In most cases our first treatment will kill green algae.  Whether the pool remains clear for the week depends on how much algae there was in the pool and how quickly the dead algae is removed.  Once the water is treated, the algae will be killed.  Now it’s up to the filter to remove the dead algae. 

For best results, put the filter on 24 hours daily and backwash (or clean the cartridge) when the pressure indicated on the gauge increases by 10 Psi.  The filter may need to be cleaned several times before the algae is gone. If the algae is allowed to remain on the bottom, the decaying of the algae will consume the chlorine at a greater rate and the water could go green again.  Once a pool has turned green it usually takes about 3 times as much chemical to bring it back to blue than it takes to maintain it for a week.  It’s very important to note that while we can kill the algae easily enough, it’s up to the filter to remove it.  Chemicals won’t make the dead algae go away.

"Mustard" Algae is also known as leaf algae.  It is a darker green color than floating algae.  Many people believe it is chlorine resistant but this is not correct.  Chlorine will kill mustard algae easily.  It’s important to add the correct amount for an effective treatment.  Once mustard algae is dead simply brush it off the sides and bottom of the pool or run the pool sweep.  Even with a sweep you’ll have to brush the steps and anywhere the sweep doesn’t reach.

"Black" Algae is the toughest of all the algae that we deal with.  Black algae can’t be killed, only controlled.  Once a pool has black algae it will have it forever.  Black algae is unique in that it has roots that penetrate the plaster surface of the pool.  These roots can grow through the plaster and into the Gunite of the pool.  Even if all the plaster is chipped off and the pool is resurfaced, the black algae will return.  What can be done about it is to keep the pool rigorously chemically maintained.  While we can’t kill black algae we can control it so it’s invisible.  It will only return when the chlorination of the pool is insufficient.  If black algae is present we will super-chlorinate the pool and hold the chlorine residual higher than usual.  At this point the customer should brush the pool with an algae brush (a brush having stainless steel bristles).  This will score the heads of the black algae colonies and allow the chemicals to penetrate more easily.  After a couple of weeks the black algae will begin to turn gray and slowly disappear into the water to be removed by the filter.  If the chemical balance of the pool goes astray the black algae will return.  

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