We strongly recommend self-testing your pool water weekly/fortnightly with a 4 in 1 test kit and the Copper Test Kit provided with the system. It only takes 5-10 minutes so make it part of your routine.
Further to this you can also have your local pool shop do a water analysis every 4-6 weeks and be sure to ask them to test for phosphates.
The instructions on the back of your Naked Water Bottle that was supplied with the system will assist your local pool shop understand your Naked Freshwater Pool System as well as the attached document Naked Water Testing Instructions.