ph and nitrate

[mossman604]

last nite i bought a nutrafin mini master test kit, when i tested my ph it read purple not even on the chart, so im guessing it would be a high reading due to chart colors. so anyway i used the ph 600 tester and it said 7.8, then i also tried the test strips and they said what the ph 600 did, 7.7,

what do i believe¿

when i tested with the test strips, it said my nitrates were high, how would i lower them.

1 more question are the test stripe ok to use rather than a liquid kit

thanks