Pools are meant to be inviting, refreshing, clear, sparkly but not green! What happened? I’ve always had a clear blue pool, never had any issue until today… woke up to find my pool was green! Why this time of all times?
Pool owners often come in asking what happened, or why is the pool green? A pool can turn green for many reasons, most common reason: algae! Although green discoloration of the water can also occur during pollen season or chemical reactions when pH, total alkalinity or sanitizer are off kilter.
However, green algae, one of the most common forms, can occur very quickly – within hours under ideal conditions. Meaning when chlorine levels are low, pH is high and the weather is warm and sunny. Think about it, algae is a living organism and its a plant so it thrives in sunlight. Most times adequate chlorine levels will hold off chlorine but most people don’t realize that chlorine can dissipate very quickly with warmer water and higher UV levels. What may be fine levels during normal summers don’t do the job when its extremely hot. Bather loads increase, meaning more contaminants taxing the chlorine and before we know it… an algae bloom. Algae spoors are always present in pools but they are mostly dormant and under control so we don’t notice them until the chlorine dips and then suddenly it goes green. Lack of circulation and filtration can also be causes, best to circulate during daylight hours when sun is strongest – stagnant water is like a pond asking for green to set in. Sometimes algae can take days to appear and start off as tiny patches on the pool floor but it can also go full blown green in a matter of hours. Algae grows at an exponential rate!
So what do I do about it? Well, the best course of action is to always get your water tested by a pool professional so you are clear on exactly what chemistry needs to be adjusted and in what order. However, the next best thing is to test the water yourself with a chlorine and pH test kit or test strips and see is there truly a lack of chlorine and is the pH off?
The best recipe for dealing with algae is; with the pool circulating 24 hours per day First – shock the pool with a high concentrate chlorine preferably granular (as liquid chlorine is far weaker) this will kill the living algae as well as leave a high chlorine residual to prevent further bloom. Second, follow up with a strong algaecide, this prevents future blooms and keeps whatever remaining spoors from re-growing. Third – immediately brush the pool floor and walls, steps and all other surfaces below water level. This third step is often forgotten – algae protects itself with a coating and if undisturbed it acts like a shield against the chemical products. By brushing we ensure all the algae is exposed and the products can do their job most effectively.
Now if the pool is totally green then you are looking for a color change within the next 24 hours. It should change from green to an aqua blue – this is a good sign, you are winning the battle! If it does not change color then the pool needs even more chlorine (one dose of algaecide is usually enough). Keep shocking the pool until the color change happens, when it does your pool is on the road to recovery – but not out of the woods yet. * NOTE: always follow proper directions listed on the product labels – more is not always better and can cause other problems.
The aqua blue pool will eventually change to a cloudy white pool – this is all the dead algae suspended in the water. Your pool filter will eventually remove it as it passes through the filter media be it sand or pleated cartridges, but it can take a while. Pools in this conditions should be allowed to circulate 24 hrs / day until it is back to normal, otherwise you are just slowing down the process. Cloudy white pools can take days to even weeks to clear depending on severity and the condition of your filter and pool equipment. Filters should be cleaned out regularly during this process so they don’t become overwhelmed. When the pool is clean again it is always best to clean your filter with a degreasing solution to ensure there are no remnants of algae hiding in the sand or pleats waiting to infect the pool again. Rinsing alone will not do the job. We recommend BioGuard’s Filter Brite.
How can you prevent an algae bloom? Just keep a close eye on your chlorine and pH levels, by testing frequently, ensure your pool equipment is functioning properly and apply a preventative dose of algaecide on a regular basis. It can happen to anyone so prevention is always the easiest and most cost effective solution.
By Phil Tanguay, Manager Sani-Sol Pool & Spa