Should I add any calcium?

I think your water has enough. Others here use a calcium/magnesium supplement routinely.

Thank you so much for your help! I will be treating this orchid then for bacterial/fungal issues and adding Magnesium.

Probably wouldn't hurt to treat my entire collection would it? Dendrobiums can't have physan, correct? I have both physan and phyton available to me

I think it's a bad idea to treat unless problems are seen. Fungicides also kill beneficial organisms which may help control pathogens. It's the same reason doctors don't want to treat people preventatively with antibiotics; this selects for resistant organisms that might be harder to treat.

Instead of treating an entire collection with fungicides or bactericides I would treat the sick plants, and use a regular preventative treatment of beneficial organisms. Ray sells one you can find it on his Web site firstrays.com .

Most diseases are better prevented than treated. This involves lots of air flow, proper temperatures, humidity no higher than necessary, and not splashing water among plants.