Unfortunately, if you haven’t paid much attention to it over the winter, your pool may be a little out of control. Remember, the pool has absorbed dust, pollen, and all other sorts of material since it was too cold to swim. If you’ve started to see water quality problems, don’t fret! Here are some common problems, and fairly easy solutions.
Green algae is usually seen throughout the water, and clings to walls and steps. If this occurs, it’s likely due to low chlorine levels. Make sure you clean any leaves, sticks, etc. out of the pool as soon as possible, backwash or clean your filters, and use a high quality shock to kill the bloom (2 lbs. per 10,000 gallons is usually enough). Brush the pool and run the equipment until the green is gone. In extreme cases (You can’t see the bottom, or there is an unusually large amount of debris), it may be best to drain, clean, and refill the pool. Consult a pool professional in your area to determine if this might be the best course of action. If the green persists, you may have a state of chlorine demand. This requires a specific, large dose of chlorine to clear up. Your local pool professional should be able to test for chlorine demand and provide detailed instructions.
After the green is gone, use a flocculent or clarifier to remove the dead algae and clarify the water. Clean the filter or backwash again to make sure the dead spores are removed.
Mustard algae is usually found on the shady side of the pool in “sheets”. I’ve also seen it start many times in the spa, and then spread to the pool. This type of algae has frustrated many homeowners through its propensity to go away, come back, go away, etc. Again, strong shocking, brushing, and using more filtration is the fix. A preventative algaecide will help keep it from coming back, as will extended filtration cycles. If possible, keep birds, dogs, and other wildlife out of the pool, as this is a common means of diminishing your chlorine level. I also believe it isn’t a good idea to wear a swimsuit in the lake and then use it in the pool – there are too many “things” in the lake that you can actually reintroduce into your pool, making pool maintenance harder.
Products specifically designed for mustard algae do a good job removing it, but they don’t seem to work very well at keeping it away. Regular brushing, shocking, and longer filtration runs are the best ways to keep it from coming back.
Ask any pool pro about this one, and you’ll get a shudder. Black algae starts as a small black or dark green spot, and spreads rapidly around the pool. You’ll see it first near lights, jets, corners, or in the tile grout. While not impossible to remove, it requires a very different approach than green or mustard algae.
The visible spot is actually a waxy shell that protects the plant. Just shock or algaecide won’t do anything to budge the problem. You MUST brush with a stiff brush to remove this waxy layer so the chlorine can kill the plant. In tight areas, a pumice stone works well, or in white plaster pools, a chlorine tablet will do. In cases where there are too many plants to get by hand, use a silver-based algaecide and a large stainless steel brush to remove the coats. Use a Tri-Chlor or Di-Chlor shock to kill the plants, and keep the chlorine at the upper end of range until all discoloration is gone. Make sure you vacuum the debris out of the pool and clean your filters or backwash ASAP.
Preventative algaecides, longer filter run times, and consistent, adequate chlorine will help avoid the algae from returning. If you have any questions, ask a pool professional for advice. Most of us enjoy solving problems, and would welcome the chance to help you out.
Remember, you can prevent algae blooms with regular water testing and shocking, keeping the pool clear of organic material like leaves, dirt, or other large debris, cleaning filters and brushing the pool walls regularly. Regular maintenance should take no more than 30 minutes a week- Test the water, skim the surface, empty the skimmer and pump baskets, brush the walls, and add required balance chemicals. Then, have a cannonball contest to celebrate that clear and clean water!