Check the pH of the wastewater coming out of the filter (in filters with yellow/blue hose this can be done on the top of the bag). Measurement is done in connection with regular service visits if you have signed a service contract. Otherwise, you can easily do it yourself by either using a digital pH meter or hi-res pH-indicator paper. Note that it is important to not only use surface water when measuring since this normally shows a lower value than the actual value in the filter material. To ensure accurate measuring you can either place the digital sonde of the pH-meter directly on the filter material or if you use pH-indicator paper collect a small amount of filter material, with a planting spade or similar, from a few centimeters below the top layer and in a beaker mix the material with a splash of the water from above the filter. If the pH value is at least 9 you can rest assured that the filter still captures phosphorus corresponding to at least 90%. If the pH is below 9 the function may still be intact but should be checked by a water sample analysis. Water samples can often be sent for analysis to the supplier of your treatment plan, otherwise contact your local environmental office. There is no necessity to turn to an accredited lab.

If the water is difficult to reach from ground level, you can tape the pH paper (or test bottle) to a broom handle or similar.

pH-indicator paper should have a resolution of no more than half a pH step in the range min. pH 8 – 10. pH sticks can be ordered in various online stores but can also be ordered directly from Polonite Nordic in smaller quantities at: info@polonite.se