Q&A for How to Eliminate and Prevent Green Algae in a Swimming Pool

If DE powder is entering the pool, one or more of your septum elements is torn or not properly connected to the header.

Yes, it will not cave in if the top bars are all in place. But do what you have to do and refill as quickly as possible. Letting the vinyl liner dry out in the sun can allow it to shrink. Fill the pool on an 80 degree, sunny day ONLY. Don't fill at night.

You can brush it, causing it to stir up into water, and then let the filter grab it. However, if you do that, you're going to have to backwash it a few times throughout the process.

Yes.

Algae is not exactly harmful, but if there is not enough chlorine to kill the bacteria in algae, there might be a risk of things like infections via a small cut or scrape.

Flocculant, vacuum, shock... in that order. If you still have any noticeable algae after, repeat the next day. Do not exceed the allowable amounts of flocculant by the label as it is poisonous. Use a Phosphate remover to prevent further algae growth. Wait until chemical levels are safe before swimming. HTH Test kits found at Walmart are pretty good for testing. DO NOT swim immediately after doing this. Wait the allotted time specified on the label.

Algae is not exactly harmful. In some places it is even considered a delicacy and nutritious. Yet if there is not enough chlorine to kill the bacteria in algae, it can be a little harmful by effecting the body via a small cut, infections etc.

You have to wait at least 4 hours with the granular shock that I use. Not sure if others are different. It's best to shock at the end of the day and let it circulate overnight.

Not necessary if you keep it clean and use your chemicals properly. Water does not go bad; however, too much acid may cause a need to dump water.

It should be set on waste while vacuuming. Backwash after vacuuming till the water coming through the sand is clear.

Personally, I use a 10-gallon Shop-Vac attached to a pool vacuum hose. Vacuum, dump, and repeat. It's a longer process, but it uses much less water.

For the moment, stop using chemicals. You should set your filter to backwash and manually vacuum the bottom of your pool. I would backwash at least a third of that slimy water. When you replenish the water, it will still have algae in it. If does not show a visible improvement, then you should repeat the backwash process. If the algae has your pool in really terrible condition, then you should backwash about half of the pool. Once you get that crud from the bottom of the pool, the chemicals will become effective.

You can purchase and safely use algaecide. Your local pool supply store can advise you as to what kind to buy. We add a small amount to our pool once a week. If you maintain your chlorine levels and run your filter several hours a day (or 24/7), you should have no more problems.

You don't need to. Just make sure that the sand is filled to the proper height in the filter and change it every 3-5 years.

If you're having issues with cloudiness in your pool, I would suggest reading wikiHow's article on diagnosing and clearing pool water cloudiness for detailed instructions and tips.

Have checked your PH levels? If PH is too high it will compromise the effectiveness of shock/ bleach. Levels can read high but will not actually be working.

Backwash until it runs clear several times a day. Backwashing should flush it out. Shock the the pool heavily first.

For sure it can, but it depends on many variables. Seldom does a single large dose totally do the trick, as the sun will rapidly consume the chlorine, and as you pictured, it does run a large risk of damaging the surface. Lastly, depending on the type of chlorine shock, you'll also run a risk of greatly lowering the pH of the water, thus making a vinyl liner very brittle and prone to tearing.

Seldom does only running the pump prevent algae. Algae is almost always a result of poor chemistry and a lack of chlorine. The outlier here is if you have a salt water generator In that case you'll want to run the pump for long enough to produce enough chlorine to keep your pool clear. Running the pump is needed to help circulate any chemicals you add and keep the surface lean. Circulating the water will help make sure the sanitizer is evenly distributed.

Unless you use products like "flock" or any "clairifiers" there's almost never a need to change the sand. Think of how many years that sand has been around, a few years in your filter isn't going to hurt anything. Every now and then a good "deep cleaning" of the sand filter will help remove any debris that may get captured in the media.

Shock is chlorine. The only difference between granular chlorine, chlorine tabs, and shock, is that some have stabilizers that keep the chlorine from evaporating too quickly in direct sunlight. Shock does not have stabilizers, allowing you to raise you chlorine levels really high for short periods of time. This allows you to kill algae and bacteria quickly, before returning to safe swimming levels.

Algaecide comes with its own set of water conditions. Anything added after those conditions are met could affect your PH levels and render the algaecide useless.

Yes! "Saltwater systems" are just automatic chlorine generators. An electrical charge is sent to a metal plate in the salt water cell. When grains of salt come in contact with the plate, they are converted to chlorine.

These methods are intended to be used for swimming pools. Do not add chlorine to any water that supports living organisms you intend on keeping alive, without first checking their tolerance levels for chlorine.

"Backwash" gets rid of the particles (that get caught as they get pulled down through the sand) on top of the sand in your filter. Backwashing releases those particles out a hose off your filter system. "Rinse" is something you do after you have backwashed. You shut the filter and turn your dial from backwash to rinse, turn your filter on just for a few seconds (rinsing out the line from backwashing) then shut the filter, turn the dial back too "filter". It is a cycle that should be done approximately once a week or by the change in your pressure gauge on the filter.