Regarding your Tetra pH test, I have had BAD results with mine. I kept increasing pH at first so the Tetra read in the 8.2-8.3 range but when I took a sample in to my LFS
, my pH was 8.8
After that, I bought both the Red Sea and API pH tests, both of which read 8.2-8.4 when the Tetra shows 7.7. Maybe someone else will chime in on the Tetra brand, but I'm wary after that episode.