Ive got a sticker thermometer thats on the outside of my tank and i noticed theres different colors on the thermometer.

right now I see purple is on 70 blue is on 72 and brown is on 74. Ive always been guessing. does that mean its 72 degrees?

A sticker thermometer will read a "range" of temps. The "purple" means that it is higher than the number shown, the blue means it is closest to that temp, and the brown means that it is lower than the temp shown. So, yes, your tank is approximately 72F.

thanks Daryl