Digital PH meter Probs

Ok, well I am starting to get aggravated with PH testing. I got a PH controller with my hydro setup. This is the controller: http://www.stealthhydroponics.com/product.php?xProd=136&xSec=27

So after using it for about a week (I didn't try calibrating out of the box because it said it was calibrated from the factory) i find out that the readings are off. I got a packet of about 80 PH test strips with my setup. So in comparing results between the two I found the digital was way off. I got calibration solutions and attempted to calibrate the digital. Problem is I could not get the calibration to work on the controller because I could not get it to calibrate with the 4.01 solution. Lowest I could get the meter to display was 6.84 or something around there. So I said screw it I need a meter for now and I ordered a Hanna PH/Temp meter. It came in today, this time I calibrated before using it. Calibration went smoothly and according to the meter was a success. So I go and check my water and the meter displays 7.1. Well last night with the ph test strips my ph was around 5.5-6.0 so I know something is up. Not knowing if the test strips were bad or the meters I decided to try one of the test strips in the calibration solution. Reading came out perfect, exactly what it should be on the strips, 7.01. I tested the water again with the strips and I am still in the 5.5-6.0 range according to the strips....

This is starting to piss me off because while the strips are good and all, I would like to get an exact digital readout of the ph. Anyone have any similar experiences? Am I doing something wrong? I find it hard to beleive I have two defective meters that are both less then 2 weeks old. Any suggestions on what might be causing the readings from the digital to be so far off the strips?

ph can fluctuate after a feeding as the plants take nutes out it alters the ph.. may rise it, or lower depending on the nutes the plants use.

so you calibrated the hanna testor in the calibration solution and it worked? now just test the calibration solution and it should read it correctly.. and you then know if it's reading right..conversely, you know if it's not.. if it's not then go by the strips for now is my suggestion..

my testor is a $30 one off ebay. never "had" to calibrate it in over 6 months.. i do it every month regardless, but it's not been out to require it...adjusts itself based on the temp of the res and one touch calibration. stick it in the solution and hit the cal button. I had a bunk one before that and i feel your pain.