Having a pool is great until you run into a problem that you are unsure how to address. Not much is worse for a new (or even experienced) pool owner to see than a pool full of green water. While there can be a few causes for a green pool, it is most often a result of algae overgrowth. This too has several different reasons.
pH and Algae
Out-of-balance pH levels can cause a huge range of problems for pool owners, from skin and eye irritation, damaging of the pool’s components, leading to a bacterial or algae overgrowth. Regardless of the direction, it is out of balance, this can cause real problems for a pool owner. When left untreated, it can lead to severe discoloration of the water, which can be a bit of a bear to solve. If your pH is too high, the chemicals in the water may not be enough to kill bacteria and algae, which can lead to rapid and dramatic algae overgrowth.
Filtration and Algae
Algae overgrowth can be a sign of a bigger problem than just a chemical imbalance. It can also indicate that there is something wrong with the pool’s filtration system. Clogged or broken filters work less efficiently, and thus will have a hard time keeping the water clean. If it is broken, it is not able to filter the water at all, leaving it susceptible to the growth of algae, mold, and bacteria. If your filter isn’t working right, not only will algae grown, but other potentially-harmful substance can also survive in the water, rendering it unsafe to swim in.
Weather Patterns and Algae
There are prime conditions for the growth of algae: humid and warm environments. With this in mind, it shouldn’t be surprising that a pool is a highly attractive place for algae to take up residence. Changes in the weather, such as an extended period of rain or excessive humidity, can change the conditions of your pool water which may necessitate a recalibration of your daily chemical usage to meet these changing conditions.
Clearing Up Green Pool Water – What to Do?
The answer to this simple question is: how bad is it? Algae and mold overgrowth can quickly get out of hand and chemical treatment may not be enough to take care of the problem. If your water is brackish and you can’t even see the bottom of the pool, you will need to take more drastic measures. In this case, the best solution is to do a full drain of your pool. While it is drained, you will want to do an acid wash of the surface to kill and remove any algae from the surfaces of the pool.
If the water is discolored and you can see algae, but you also have at least six inches of water visibility, you may be able to treat the problem with chemicals as opposed to draining and doing an acid wash on the pool. Chances are, if your problem can be solved chemically, it will involve getting your pH levels back in the appropriate balance. When algae are the problem, it means you need to lower the pH. Doing a water test will give you the measures you need to know just how out-of-balance the levels are and thus how to go about addressing the problem. You want the pH to be between 7.2-7.5. Sodium bisulfate is available at most pool supply stores and is highly effective at lowering water pH when used according to the manufacturer’s instructions. It is easy to overdo pH reducer, so you want to make sure that you follow the instructions on your specific brand and type.
Green water also means that your chlorine levels are low or algae wouldn’t be able to proliferate like it is. Shocking your pool can be a simple and highly effective way to get the green out and to get your water back in balance, chemically. Since shocking is a method of super chlorination meant to sanitize the water, it will instantly kill off algae, as well as mold and other bacteria. To effectively kill off algae, you want to get your chlorine levels up to 30/ppm during a shock for algae removal.
If the problem with algae is in your filtration system, you will need to address this. If you have a sand or diatomaceous earth filter, you must regularly backwash your filter to keep it clean and free of excessive debris. Almost all pool systems have a backwash setting. You engage this setting and turn on the pump and backwash until the water runs clear. This should take about 2-3 minutes.
Failure to backwash can lead to clogged and ineffective filtration. Though it doesn’t happen often, this problem could indicate that it is time to change the sand or DE in your filter. If you have a cartridge filter, remove the cartridge and use a hose to clean it off well. If it is too clogged to be cleaned, it is time to replace the cartridge.
Some pool owners swear by algaecide as a great preventative measure. It makes sense when you consider that you can do all the things described here and be dealing with the same problem again a couple of weeks later – algae can proliferate incredibly quickly and it is very hardy. For these pool owners, after doing all the necessary water and filter tasks described above, they also add the manufacturer-recommended amount of algaecide to the water.
Algaecide is effective at killing off any microscopic remains of the algae and those pesky spores. Once they have been killed, they will fall to the bottom of the pool where the circulation and filtration system will remove them from the water. Having this in the water can also reduce the likelihood of it returning. People who use algaecide have to use it regularly to ensure that their pool is protected.
Will Bleach Clear Up A Green Pool?
YES! Although pool supply stores will general recommend Chlorine tablets to chlorinate your pool, it is certainly possible to use typical Clorox-type bleach. Since this is a pretty complex topic, we’ve created a separate article on that topic here.
Keep It Covered To Avoid Green Pools
Though it is frustrating and can be a hassle, one of the best ways to protect your water is to keep your pool covered when not in use. It will not only help reduce the amount of debris and other nasties that can make their way into the water, but the cover will also protect the water from sunlight, rainwater, and other things that can alter the chemical balance of the water or aid algae in its growth.