What’s wrong with miltoniopsis leaves

[Irisha99]

Hi.
Something is happening with my miltoniopsis. The leaf tips are turning brown and then it spreads it makes the entire leaf yellow. Is it the fertilizer ?
I keep it Away from windows. Day temperatures are in the 80-90F. I turn on the AC for the night and keep the room at 72F. Humidity is around 50-60%. I water it as needed, about every 2-3 days. Roots look nice and green. It’s growing in ceramis with sphagnum moss on top. I was fertilizing it every weakly weekly (I used 20-10-20). But since I noticed those brown tips I stopped fertilizing. So now just watering it with sink water.
Any thoughts what’s causing the problem? Thanks

[orchidsarefun]

Generally speaking Miltoniopsis prefer cooler conditions. I would do the reverse of what you are doing - aircon during the day and open windows at night, where temps can drop to the 60s and airflow is better. Yep, I know. Easier said than done. Photo is mine in the basement. Temperature hit 77f 1x, the rest - under 72f.

[Irisha99]

At night Temps are not Going down to 60’s. It’s in the 70-80F. So you think it’s the heat that does that to the leaves not the fertilizer?

[orchidsarefun]

Persistent heat causes issues.
As we head into fall overnight temps do drop.... ours here already have.

[Irisha99]

Here in NYC temps are at its highest. So poor miltoniopsis is suffering. Should I cut those yellowing leaves off? Keep AC running through the day, right? That’s one expensive plant lol.
Thank you guys😊