I have had my pool for a couple of months now and FC has always read 4-5 using my TF-100 test kit. The only chemicals I have ever added to the pool is muriatic acid. For no apparent reason the chlorine reading was orange on the 10th of November, with my intellichlor running at 40%. On the 11th I did the FAS/DPD which gave me a level of 18. I turned the intellichlor off and retested today and the result is still orange. Does anyone have any idea why this is happening? Could the intellichlor be malfunctioning?