OK. Orange means TC > 25 or so.

I just wanted to double check your figures. Do this:

1. Collect some pool water, and mix exactly 1/2 cup of pool water and 1/2 cup of distilled. Test the chlorine level of THAT mixture using the 10 ml sample (0.5 ppm per drop of FAS solution). Multiple the result x2. That's your FC reading. Then, test your pH with the mixture. Take that reading directly, as your pH.

You can't test pH using phenol red when the TC gets above 15 pm. But you can dilute by 50% with *distilled* water, without changing the pH. However, the TC will be lowered by 50%, the phenol red can function as expected.

2. Tell us what FC and your pH readings are, and what you pool water looks like AND what the algae spots look like.