Since you live in Phoenix, you may have some "other issues"..? If you have been fertilizing every two weeks, even with a likely "low salt" Orchid fertilizer, you could still have extra salt build up? If you use softened water, the sodium levels will probably be high. "Outside/City water" in Phoenix may also be more alkaline, leading to salt burn? The yellow edges could also mean that your Nanner is suffering from very low humidity levels? By no means an expert. But...food for thought from a "tropical transplant", trying to grow tropicals.......?
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