Arctic Pure Adjust Down lowers the pH of your spa water. It is an essential part of hot tub maintenance. If the pH of your water is high, the water will be alkaline and the chlorine is prevented from doing its job since it combines with other materials in the water. This can sometimes cause an unusually strong chlorine odour that is not found when the pH is balanced properly. The water can also become cloudy, and eye irritation can develop. The scale build-up may also start to form.