Hello, pool owners. If your pool looks like this, chances are you want your pool looking like this. In this article, we’re going to walk you through the steps of turning your green swampy pool into a crystal clear oasis.
The number one cause of a green pool is algae.
Algae will start to grow in your swimming pool if there’s a lack of sanitizing agents
in the water. Chlorine is by far the most popular and most effective sanitizer that’s being used in swimming pools today.
If you have a green pool, you most likely have little or no chlorine in your water.
Maintaining a proper chlorine level is the key to unlocking a crystal clear pool.
Here at Inyo Pools, we have adopted the SLAM method for cleaning your green pool.
The SLAM method was coined by our friends over at troublefreepool.com and stands for
shock, level, and maintain.
This means you’ll bring your chlorine up to shock level and maintain the pool at shock
level until the algae is killed off.
In this article, we’ll show the SLAM method being used to clear up a pool that we worked
on the Longwood, Florida.
This pool had been neglected for four years and it literally turned into a swamp.
We’re talking about hundreds of tadpoles, frogs, and four years’ worth of sludge, dirt,
Even though this was an extreme case of a green pool syndrome, the same method can be applied to any green pool scenario. Before starting, you’re going to need some essential items. First, a FAS-DPD Test Kit is required to measure free chlorine at height levels. Next, you’ll need also a telescopic pole, net, brush, and vacuum.
The first step will be to clear your pool of debris. Organic material is a consumer of chlorine and the more you can remove early on the less chlorine you’ll need to use later.
Depending on how bad your pool is, the debris removal can be a big project or small.
In the case of the pool we were working on, this was one of the more time-consuming parts of the process as there was an extreme amount of debris in the pool
Surface skim, deep net, and vacuum as much debris as possible. If your pool floor is extremely dirty as in our case, we recommend vacuuming to waste to avoid clogging up your filter.
The next step is to test and treat your pool water. It’s best to start out by testing your pH because once you start to SLAM the pool with chlorine, your pH readings will not be accurate. Your pH should be between 7.5 and 7.8. If your pH is above 7.8, use muriatic acid or pH decreaser to lower the level. If your pH is below 7.5, use a pH increaser or soda ash to raise the level.
Next, you’ll need to test cyanuric acid in your pool, also known as CYA or stabilizer.
The relationship between free chlorine and CYA is possibly the cornerstone
of the SLAM process.
As mentioned before, chlorine is consumed by organic material which is also consumed
by UV rays from the sun. CYA acts as sunscreen for your chlorine.
If it is too low, the chlorine will rapidly be consumed by the hot summer sun.
However, if your CYA is too high, the chlorine’s effectiveness will greatly be reduced.
30-60 parts per million CYA is an ideal range for non-salt water pools.
For saltwater pools, 70-80 parts per million is recommended. If your CYA is above or below the recommended levels, use the pool math calculator to calculate how much you will need to add or remove from your pool.
Remember, the only way to remove cyanuric acid is by lowering water levels
and adding fresh water. Take special care when adding CYA. Once your CYA is at proper levels, you can move on to testing free chlorine. A FAS-DPD test kit is required for the SLAM process which will allow you to read the high chlorine levels required to shock the pool.
If your pool is as green as ours, it’s likely that you will have a reading of zero parts
per million free chlorine in your pool.
Next, it’s time to determine the shock level you will use to SLAM your pool by referring
to the trouble-free pool CYA chlorine chart.
This chart list of free chlorine shock level that corresponds to the CYA reading you took
The pool we worked on had a CYA reading of 30 parts per million. According to the chart, we need to reach a shock level of 12 parts per million free chlorine.
Use the pool math calculator to determine how much chlorine you’ll need to reach
shock level. We needed to add 3 1/2 gallons of 10% liquid chlorine to reach 12 parts per million. Make sure you leave your pump running 24/7 while SLAMing your pool to ensure proper circulation and filtration of the water.
Oftentimes, many people will shock their pools and call it a today, but the first par
of the SLAM process is useless without the last, which is maintaining shock level.
Because chlorine is consumed by organic material and sunlight, the chlorine level will constantly be depleting as the algae is killed off.
It’s extremely important to maintain your required shock level to ensure that the algae
will not bounce back if free chlorine levels drop.
We recommend testing free chlorine every couple of hours at the start of the SLAM process and continue adding the appropriate amount of chlorine to maintain shock level.
As algae is killed off, the chlorine will start to be consumed more slowly
and won’t need to be checked as often. Now that you have chlorine in your pool and you’re maintaining your proper shock level, the waiting game begins.
It’s important to backwash or clean your filter daily to remove dead algae that your filtration system has picked up. Continue to vacuum your pool floor each day to get rid of dead algae that has settled to the bottom, and don’t forget to brush your pool walls to dislodge algae which is clinging to the sides of your pool.
You should see a noticeable difference each day as your pool transitions from green to
cloudy blue, to clear. Once the pool is clear, it’s time to perform the overnight chlorine loss test. This test will let you know if there is any more algae remaining in the pool.
First, take a chlorine test in the evening after the sun has gone down
and record the levels.
In the morning before the sun comes up, test your free chlorine again. If the reading has stayed the same or has dropped less than 1 part per million and your and your combined chlorine is less than 0.5, then there are no more organic contaminants in your water
and you’ve passed the OCLT.
However, if your free chlorine has dropped more than 1 part per million and your combined chlorine is above 0.5, then you will need to continue to maintain your pool
at shork level and perform the OCLT the following night.
Once the OCLT is passed, you’ve completed the SLAM process. Now that your pool is looking great again, it’s important to maintain your target chlorine levels in relation to the CYA levels in the pool.
Perform weekly tests of pH, free chlorine, and CYA, and brush and vacuum your pool weekly. For a more in-depth look at the pool we SLAMed, visit us over at inyopools.com/blog. If you want to perform the SLAM process on your pool after reading this article, feel free to leave a comment down below that includes your test results and pool size, and we’ll do our best to help you out.