Help! How fast can I drop temperature?

[Tnops]

Morning fish folks, my heater got to 91 degrees today in my QT. (Yes it was plugged to a controller, the sensor fell out of the tank). Foxface seem stressed but other fish just seem hyper active. The fan and ice packs are already doing their job. How fast should I drop it back down?

 

[Reefer Matt Verified Media Partner]

I'd get an air stone in there too. From info I have read, higher temps lead to lower O2 in the water.