I'm raising some baby ranchus which require 100% water change everyday so a reliable thermometer that gives fast readings was in order. I found a meat thermometer on Amazon that has been a complete blessing to have on hand. Here's the link to it: http://www.amazon.com/gp/product/B0089O0W1G/ref=oh_aui_detailpage_o02_s01?ie=UTF8&psc=1 My experience with aquarium thermometers they sell in pet stores was dismal. Nearly every single one (out of four) I had bought previously, plus a digital aquarium one off of ebay, all gave different temperatures. Since the main reason I need a thermometer is to make sure water temps match when water changing, the need for a thermometer with a quick reading also rose higher on my needs list. So I went and found the best meat thermometer I could find with a good rating on Amazon and bought it. It cost $18+ but was worth every penny for its speed. So if you are frustrated of not knowing your tank's temp and tap water, I highly recommend this one with one caveat: if you have multiple tanks, please sterilize the thermometer before you use it in the next tank with 70% rubbing alcohol.