High alkalinity - but PH level ok

[birdman]

Thanks - I filled out the entry form.

Total chlorine is 3.1
pH is 7.3
TA is 170
Calcium hardness is 300

Plus, I forgot to mention there is a yellow-ish dust (in patches) at the bottom of the pool. Is that mustard algae?

Is there more information needed? Thanks so much.

[PoolDoc]

How are you testing? Those don't look like values from a kit.

Anyhow, assuming those values are correct, you'll want to keep your pH in the 7.0 - 7.2 range for now. If you do -- it will require repeated additions of acid -- your TA will drop.

You omitted one of the the most critical measurements: CYA or stabilizer. You need to find out what your level is, read the Best Guess page linked in my signature, and then adjust your chlorine levels accordingly. Given that you probably DO have mustard algae, you will almost certainly need a FAS-DPD chlorine test in order to manage the correct chlorine levels. Read the test kit info page linked in my sig.