I would not make any decisions or chemical adjustments based on those test strips.
Since you see how far off the CYA reading was when you did not put any in, you see how inaccurate the "guess" strips are, not only for the CYA reading but probably for ALL of the reading, making them all suspect. Even the "change" from one day to the next is suspect.I’m not lol I was asked what made me think that my CYA was in an ideal range. I basically was using the strips to see if the water chemistry changed after I put the liquid chlorine In the pool.
When is your test kit coming in? When it does, there will be a slight learning curve.
TF100TestKit (on their u tube channel)
K-2006 (google search u tube)
Then plug in all your numbers to see what you need to add to the water.
Have you decided how you will work on clearing up the brown iron water?
Press on. You're going to need a lot of P.O.P (pool owner patience).