Fitter2004 said:

I started my current grow with drops. After a week of veg I bought a HM meter and calibrated it. I was keeping my nutrients at roughly 5.5-5.8 with drops. When I checked it with my new calibrated meter it was reading 6.9. I recalibrated the meter to 4 instead of 7 and still pH was 6.9. I then adjusted nutrients down to 5.8 with the new meter. I’m still curious as to why the drops were so far off? The color difference between say 5.5 and 7 is a very noticeable difference. Did I contaminate solution somehow? Plants are doing great and nutrients hold steady at 5.8 with ppm of 750.

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