How do I know when it’s time for a sand change?
What ‘sand’ are we talking about?
It is the sand in your pool filter that traps and collects grease and oils, minerals, organic material (such as algae) and other particles. Sand is an excellent filtration medium, and trapping these contaminants and particles keeps your pool crystal clear and free from pathogens. The filter medium used most often is sand – more specifically, silica sand. Mined from ground quartz, this sand is characterized by sharp, jagged edges, making it a very effective filtration medium. When compacted together in a pool filter, these grains – smaller than a millimeter – create a filtration capability as small as 20 microns. That is less than half the width of a human hair. This allows your filter to trap particles of any size, from dirt to certain bacteria, and prevents it from going back into your pool and causing cloudy and pathogen-laden water. The source of your pool filter sand is important, as not all types of sand are created equal. Alternatively, you can opt for an environmentally friendly option. Glass as a filter medium has gained some traction in recent years. Made from 100% recycled glass, it is smooth to the touch, but still captures particles as small as 2 to 9 microns. Glass may be a better option, but it is a much pricier alternative to silica sand.
Why do I need to change my sand?
Over time the jagged edges of your filter sand become smooth or rounded through a process called weathering. Friction between the grains causes them to smooth out and so diminish their filtration capacity. Early onset of the smoothing of your filter sand can occur when your filter is not the right size for your swimming pool, and the same goes for the pump's capacity being matched to the size of the filter. Another common reason for a sand change is when your filter sand gets so saturated with oils (left by sunscreen, tanning lotions and hair products) that it clogs up the filter. This causes the sand to create channels (imagine an ant farm and the tunnels they create in the soil), which essentially means the water passes through your filter without being filtered by any medium. In the last case you can, in some instances, salvage your sand by using the backwash function on your filter, along with a chemical cleansing product to break down the oils. Important to note is that living organisms propagate in this clogged environment and can cause serious illness if the situation is not addressed in time.
When to change your filter sand
This is somewhat of a controversial subject. There are two camps of thought on the frequency at which you should do it, or get your friendly professional to do it for you. The first would be those suggesting a shorter time frame of about 18 to 24 months. It is believed that this is the number of months after which the returns of the sand’s filtration capacity start to diminish. The other suggestion involves a longer time frame from one sand change to the next, which is about three to five years. So which way do you go? We believe that rather than using a timeline as your measure, observe certain signs telling you that your filter is not performing quite like it used to. You will start to notice, among other things, that your pump needs to run longer to keep the pool water clear, you spend more money on chemicals to assist with filtration, have more frequent backwash cycles and increased difficulty in controlling algae. The efficacy of your automatic pool cleaner can also be used as a good indicator. If your pool cleaner is not working as it used to you can do a simple test to see if the fault lies with the filter or somewhere else. By simply switching the multiport from the ‘filter’ function to the ‘bypass’ function, you can assess if your automatic pool cleaner’s performance changes. If the performance remains the same, the problem lies somewhere else, for example, a leak in the lines either to or from the pool pump. Should the automatic pool cleaner all of a sudden work better on bypass, you may need to inspect your filter sand. Using glass as a filter medium may be a more expensive option, but it lasts about two to three times longer before it needs to be replaced.
How do I maintain my sand?
By using the ‘backwash’ and ‘rinse’ functions on your multiport you can help your filter sand trap particles more efficiently. Backwashing rinses the sand, flushing debris to waste. It can be done as part of your routine pool maintenance every two to three weeks. You can also use the signs visible in your pool as a measure of when you need to do a proper backwash. You will perhaps notice more cloudiness in your pool water, even though the pump is still running the same number of hours than before. Your automatic pool cleaner may also appear to be less effective and moving slowly, not efficiently climbing the walls of your pool. This points to a water-flow issue where the rate of water passing through the filter is restricted due to clogged-up filter sand. Monitoring the pressure in your filter is the easiest method to determine whether you need to backwash should you have a pressure gauge on your filter. Any reading from 8 - 10 psi above normal operating pressure means a substantial amount of pressure has built up in your filter due to water not being allowed to easily pass through the filter sand. By running the pump on the ‘backwash’ cycle for about two minutes and then another one minute on ‘rinse’ should return the filter to its optimal performance. If you want to give your sand a little extra cleaning, use a filter cleaner product. It chemically washes/degreases your sand, getting rid of oils from suntan lotion and other contaminants that are not cleared with backwashing.