Slamming or shocking your pool is necessary if the chlorine level in your pool has dropped below the minimum level necessary for sanitation and to prevent algae growth. If your pool is cloudy or even green, you will need to slam the water with chlorine. Fortunately, chlorine is both easy to use and very effective. You need to maintain a level of 3 parts per million to stave off algae and bacterial growth. Unfortunately, if you let that level drop for even one day, algae and bacteria will start to grow. If you have a fiberglass pool, the water is left in the pool over the winter, so a green pool in the spring is the norm. You may also find the water in your pool is anything but clear when you return from a vacation. If you are maintain proper free chlorine (FC) levels there is no need to SLAM, but if you find that levels have dipped, slamming is a must.

Test Your Pool Water First

To do a proper test on the water, you will need a FAS-DPD chlorine test kit. This measures Free and Total Chlorine in small increments. The colour changes and allows for accurate readings, even at very low or high chlorine levels. Don’t bother with litmus strips to test your water. They are too inaccurate and bleach out from the water. Take your sample as deep as you can from the water and away from returns. You will also need to know the level of Cyranic Acid (CYA) in your pool. CYA is important as it is a stabilizer and protects your chlorine from degradation by the sun. The higher the stabilizer level, the higher the free chlorine required to sanitize the pool. Testing is done with the same kit. You do not want your CYA to be higher than 50ppm. At very high CYA levels a partial drain and refill are needed to lower the CYA level. There are charts available online that will help you determine the optimum amount of a slam you want dependent on the CYA and FC levels in your pool.

SLAM Your Pool

Slamming can be done with liquid chlorine, bleach or shock. Crystals must be pre-dissolved in a bucket before adding to the pool. If possible, do the slam at night so that sunlight does not affect the results. Give the pool a clean before the slam so that it is free of as much debris as possible. If you have a tablet chlorinator or other chlorine feeder, shut it off completely. Add chlorine according to the chart to try to bring the free chlorine up to the proper level. Wait at least 30 minutes and test your water again for free chlorine using the FAS-DPD test. Record the result. Do not put any more chlorine in your pool.

When To SLAM Your Pool

As early in the morning as possible and before there is sun on the pool, test the water again and record the results. If your free chlorine level is the same as it was form the night before, or if it went down by less than 1.0ppm, you are done. The water is clean and organic contamination has been eliminated. If the free chlorine dropped more than 1.0 ppm, you must add more chlorine. Continue to slam the pool until it tests clean. If you follow these simple directions and maintain the chlorine levels in the pool you will eliminate the possibilities of algae bloom and bacterial contamination. Chlorine products are inexpensive to use and do the job well, so test and slam the water whenever levels drop. Have questions about how to properly SLAM your swimming pool?  Contact us here, we're happy to answer any pool chemical questions you may have.  Discount Pool Supply is the online leader when it comes to buying pool supplies online in Canada.  We offer thousands of products at great prices and provide free shipping across Canada!