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The most important factor to inhibiting algae growth is the amount of free chlorine, not so much the other water balance factors (except temperature and pH). You could have alage on the boulders for the following reasons: 1) The amount of free chlorine in your pool is enough to inhibit growth of alage in your pool, but not in the different conditions on the boulder (see below). 2) The boulder and water flowing over it may be at a higher temperature, especially towards the bottom boulders, if they are exposed to the sun. Higher temperatures promote more algae growth that could outstrip the available free chlorine. 3) If the boulders are exposed to the sun, then this may be reducing the amount of available chlorine, especially if you do not use any conditioner (Cyanuric Acid). 4) The bubbling and aerating of water may convert much of the chlorine to gas via HOCl + Cl- --> Cl2(g) + OH- which is more likely in a salt pool due to the extra chloride ions from the salt to begin with. Do you notice a chlorine smell near the top boulders? 5) Areas near the edge of the water flow do not get enough continuous exposure to the pool water for the chlorine to kill the algae, but get enough water for algae to form. Also, if the water pools so that chlorine is released to the air faster than the pool is refilled with new water, this could promote algae growth. This is similar to poor circulation in a pool. As for what to do, the easiest thing is to treat your boulders with an extra "shock" of 5-10 ppm chlorine (which could be done when you shock your pool with liquid chlorine). Do NOT shock your pool with just the chlorine generator as this will not build up enough chlorine fast enough to kill some more aggressive algaes. Use liquid chlorine to shock your pool, or at least your boulders.

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โˆ™ 2004-10-28 17:40:01
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Q: Why would algae form on the boulders of the waterfall if your salt water pool is in chemical balance?
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Related questions

Chemical formula of algae?

Chemical formula of Algae: C106H263O110N16P Chemical formula of Algae: C106H263O110N16P Chemical formula of Algae: C106H263O110N16P

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Algaecide can usually get rid of algae. Unless the water in circulating there is no way to prevent algae buildup on wet surfaces.

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Light is made by algae by a chemical reaction that the algae produces in order for the algae itself to have enough food to survive. I suppose it is quite a natural and interesting chemical reaction.

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Some algae can produce toxins.

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Balance your chemicals

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Algae are very slimy and will not get out just by ordinary washing. The slimy coat on top actually protects the algae from reaction to the chemical composition that is used to clean the pool. To make sure the algae does not stick around even after chemical treatment of your pool, scrub the algae to break the slime and expose it to chemical reaction. By doing this, you will expose the algae to react with the chemical treatment when you eventually shock the pool.

Which of the following contains chemical energy (APEX)?


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This chemical is agar.

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copper sulphate

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If you have a waterfall do you still need a biological filter aerator and ozonator for your koi pond?

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Adding algae control to the pool skimmer helps to disperse the chemical and coats the filter media.

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Physical, because the algae is not chemically combined. It is simply little particles floating around in the water.

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