Thermometer Issues

[Laser]

I had an encounter with Ich so I raised the temperature to what I believed to be 86 or 87. However, I just got a digital Marina thermometer and it's holding steady at 90. My previous thermometer was a Marineland strip. It had 88, 86, and 84 highlighted, so I figured it was around 86. I don't know what to believe, but I'm more inclined to believe the Marina thermometer. It's been 10 days and my fish seem to be doing fine with no sign of stress from my Cory's. What do you guys think?

Edit: Now it says 91... lol

 

[Laser]

Well, I may have just answered my own question. I just placed the thermometer by my house thermostat and it matches it perfectly. Time to go apologize to my fish now...