Weird reading with pH meter

Has anyone encountered their pH meter changing readings just by the light they're taking the sample in?

I was just using a regular clear drinking glass and scooping out a bit of water and putting the meter in it. If I read the meter under the T8's its now exactly at 5.8, if I put the glass down outside of the veg room where its less light it jumps to 7.5? I have a Hannah pH meter. Curious if the medium you measure it in matters?

Well in the endless searching I've pretty much narrowed it down.. It would appear that the electrodes or device itself goes a little haywire when its near compact fluorescent of any type. I was just setting it on my reservoir or or on the ground with the 4 bulb T8's about 20 inches above the sample I was taking.

I can walk around anywhere and hold a steady reading but the moment I get just a little to close near a fluorescent fixture the readings go up or down in any given direction. I don't use the small bulbs but just as a test i held it close to those around the house, same haywire readings occur when its right up within 2 feet of that fixture.

Hope this helps anyone else, had me second guessing pH in the tank in a big way.