Judy5350,
What type of water do you use to water your AV? Bottled water, tap water, filtered tap water?

Planto

Something with water and fertilizer. Not dangerous. Reduce your Peters to 1/4 of a teaspoon, leach soil and remove the affected leaves - they are not going to get better.
If it was a tap water - I would say chloramine. Spring water - also comes from a tap - and depending on a brand - it is filtered really well -or not.

Leach your soil with distilled water with a small amount of a fish emiulsion. Will give your plant a boost.

I.

My soil is one part each of sphagnum moss, perlite, and vermiculite. Could the soil mixture also be a problem?

Are you talking about sphagnum peat - black stuff- or sphagnum moss - the yellow chopped parts of the plant?

You can check pH.

I.