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Treating Black Algae

WHAT IS BLACK ALGAE?

Black algae is a form of algae which is black in color and usually forms in cracks and crevices on pool surfaces. It forms a skeletal growth on top to protect itself which makes it almost impervious to normal levels of chlorine. It is very hard and cannot be brushed off. To treat black algae it is imperative to brush vigorously before applying chemical treatment to eliminate the protective coating.

PREVENTION OF BLACK ALGAE

Follow the BioGuard® 3 step program of your choice as outlined in your BioGuard® Pool Care Book. The following tips can also help you in the prevention of black algae:
– Keep the pH at 7.4 to 7.6.
– Clean the pool regularly, skimming, brushing, vacuuming and backwashing the filter as needed.
– Keep the filter clean and water circulating properly. Keep the skimmer and hair and lint baskets clean. Check them often if you have a lot of cotton from cotton wood trees or debris blowing in the air around the pool.
– Keep the pool water under 82 degrees.
– Keep the water properly balanced.
– Anytime you let the chlorine residual fall below 1.0 ppm, it is a good idea to add a granular chlorine like Super Soluble® or Burn Out® Extreme (3-4 oz. per 10,000 gallons), or Burn Out® 35 (4-5 oz. per 10,000 gallons). If you haven’t shocked/oxidized for awhile, go ahead and shock/oxidize (preferably at night.)
– If you or someone in your neighborhood fertilizes with any type of fertilizer, you may want to check your chlorine residual. If it is low, shock/oxidize with normal amounts of shock/oxidize. The fertilizer has nitrogen which creates chloramines and a deficit in chlorine.
– Always check chlorine residual after rain storms. Sometimes after severe storms, you may want to shock/oxidize or add maintenance doses of algaecide.

TREATMENT OF BLACK ALGAE

CHLORINE/BROMINE POOLS

STEP 1: Adjust the pH to 7.4. If the pH is higher than 7.6, you loose 20-30% chlorine efficiency.
STEP 2: Shut off the pump. It is essential to brush vigorously to disrupt the algae’s protective coating, allowing the algaecide to penetrate more easily. Allow four hours for the water to become stationary.
STEP 3: At night, slowly add freshly dissolved BioGuard® Spot Kill® or Spot Kill WP® into water along edges of the pool. Pour more solution over areas of heavy growth. Use Spot Kill® for vinyl or painted pools. Use Spot Kill WP® for white plaster pools. The amount needed will be on the back of the bottle.
STEP 4: Pre-dissolving method: add 2-3 gallons of water to a clean plastic bucket and slowly dissolve one pound of Spot Kill® or Spot Kill WP® in the water. Stir with a wooden or plastic spoon. Never dissolve more than one pound at a time. Do not add any other chemicals or materials to the bucket.
STEP 5: Next morning, brush vigorously or scrape the algae, turn the pump back on and remove dead algae by vacuuming. It is best to brush every 3-4 hours if algae spots are visible. In extreme cases, repeat treatment.
STEP 6: Backwash filter after treating and vacuuming and use Kleen It® to clean filter. The filter can be an excellent breeding ground for algae and bacteria. Keep on brushing algae spots until algae is killed completely.
STEP 7: Sometimes, particularly in plaster surface pools, the surface portion of the algae extending into the water will be killed and some surface will remain darkened. Some refer to this as algae stain. In actuality, it is the follicles of the algae embedded into the surface which have not been thoroughly killed. Failing to continue the treatments until these “roots” have been destroyed will lead to rapid return of the problem.
STEP 8: Do not use the pool until chlorine residual falls below 3.0 ppm.
OR
STEP 1: Brush growth extensively. With pump running, apply Burn Out® Extreme or Burn Out 35®, according to Erase™ label instructions, directly to the pool. Allow to circulate for one hour.
STEP 2: Add 16 ounces of Erase™ per 10,000 gallons of water through the skimmer with the basket removed. Replace the basket after the Erase™ has been added. Let circulate for 48 hours after application. Do not swim for one hour after applying Erase™. Do not allow the chlorine level to drop below 1.0 or bromine below 2.3.

SOFTSWIM® POOLS

STEP 1: Brush growth vigorously
STEP 2: Apply two gallons of SoftSwim® C per 10,000 gallons of water.
STEP 3: Apply an initial dose of SoftSwim® A.
STEP 4: Chemically clean the filter, use SoftSwim® filter cleaner.

ALL POOLS
After eliminating black algae, chemically clean the filter and follow an aggressive maintenance program for a few weeks. Apply an initial does of your maintenance algicide to replenish the level. (Algae growth depletes algicide.) Keep sanitizer levels toward the higher end of the scale (chlorine — 3 ppm, bromine — 4 ppm, SoftSwim — 50 ppm). Shock/oxidize more frequently. It is also very important to brush the pool once a week after eliminating a surface growing algae. Black algae may sometimes grow deep into the surface and not be completely eliminated by an initial treatment.

Black algae is a form of algae which is black in color and usually forms in cracks and crevices on pool surfaces. It forms a skeletal growth on top to protect itself which makes it almost impervious to normal levels of chlorine. It is very hard and cannot be brushed off. To treat black algae it is imperative to brush vigorously before applying chemical treatment to eliminate the protective coating.

Download a printable PDF: BUL-117 – BLACK ALGAE

Copyright ©2001 ULTRA MODERN POOL & PATIO, INC.
Bulletin #117