I recently bought replacement r-0013 from Amazon. We tested CYA tonight and got about 20 after having had a level of around 10 and adding 4 lbs of stabilizer a little over a week ago. This was my husband's 1st time testing, and after asking if the dot was cloudy enough multiple times before we both finally called it 20, I had him do the control test included in my TF-100 kit to see what it should look like. He got 35 with that pool water and our new r-0013. I'd done the control test when I 1st got the kit a few weeks ago, and it came out to the perfect 50 it was supposed to. I watched him perform the test, and he did everything properly. Am I correct in thinking for the control test to be 35, my new r-0013 must be faulty?
On a related note, is there any concern in leaving my CYA around 20 until I can get better/more inaccurate r-0013 to test? Or should I go ahead and add, say 2 lbs of stabilizer to at least get things going for now?