Backyard Aquaponics
A place to discuss aquaponics

I have had a PH of well over 7 for the last year...closer to 7.6/7.7. Recently added a few filters(RFF & shade cloth filter) as well as Potassium bicarb for my hard water. I'have been treated my top off water with phosphoric acid and now it looks like my PH has dropped below 7. Since I've only used the "high PH" test before, just making sure that I'm reading it right. What do you folks say?
The tube on left is regular PH, on right, high PH.

That's why I won't use the API for pH... the colorimetric is too hard to differentiate with enough accuracy IMO. Your regular-range tube looks grey rather than on the scale but the high-range seems below 7.4 for sure... have you tried it again?

How old is the test kit? I got sick of trying to read the API kit too, so I bought a digital ph meter for $30. Life is easier now, as it can read 0-14 ph.

I bought a digital too. It's reading 6.6-6.7. Thanks.

I've also given up on API's pH test, I'm now using Sera to test pH, the API test is just too hard to read.

Which one?