pH confusion
 

I have two pH pens. One is china made the other is Milwaukee. I have used them in the past for aquariums and horticulture with no problems. Today I calibrated one for my brother to take and after calibration I tested my water to which it tested 3.4. Wow I immediately tested with my other and tested the same. So I tested my mix barrel which test 8.4.

I broke out my API kit and tested 8.4. Also tested with my Hagen witch also tested 8.4.

All is healthy and growing so I'm not overly concerned but not understanding why this is happening

Uhm...sounds like your calibration fluid is toast, or maybe you didn't use the right one seeing as you are exactly 5 points off? Did you use two calibration fluids (pH 7 and 10) or just pH 7?

I tested with 7 and 4 I've alway used a Hight and low. I trust the chem test a little more. Could also be the probes are shot. I plan on taking a water sample in to the lfs just to be sure.

The halides have been off for 45 minutes and Only t5 are on. I tested water again with both testers and now read 8.4.

Is it possible that the halides change the water on top that much.

probably more noise from the lights are effecting the probes than changing the water's pH

When testing basic you need to use basic calibration fluids. You should be using 7 and 10. The 4 and 7 method is for alkaline (freshwater). I don't think the probes are dead...why would they both die at the same time and give the same reading? That's just weird. Considering you just calibrated both of them I think it is the calibration that is the issue. Even if you think 4 and 7 is ok to use, it is quite possible that the fluid you used is not accurate.