Yes, JBL water tests work accurately at all temperatures. The temperature dependent deviations are so small that they are between the normal measuring tolerances and thus are not relevant. But do not leave your JBL water tests at the pond where they could freeze. A frost resistance test with the JBL water tests confirmed that the KH and nitrite test that had been left to freeze later indicated too low values. All other tests worked correctly after thawing. When carrying out the tests it is important to closely observe the required waiting times before the colour comparison, because the response times are slightly longer at low temperatures! And please don’t wait too long between sampling and testing: the oxygen and the pH value certainly change during the waiting time!
And don’t forget: next summer’s algae problem is created today!
Winter is a good time for pond owners to set the conditions for a pond without algae problems. In winter the algae-promoting phosphate (PO4) has dissolved from the dying plants/algae and even sometimes from the pond sludge. It accumulates in the water and thus can be detected. Now is the ideal time to bind phosphate with e.g. JBL PhosEX Pond Filter or JBL PhosEX Pond Direct , to deprive algae of their basic nutrients in the coming spring.