It normally tests within 0.2 of solution/vial and ph pen (although seems often to give lowest result), but it is several years old now (apparently these are good for 18 months although one local member has his for 3 years).
Just noticed the drop checker is well into the yellow and ph injection turned off. I think this new, full bottle of CO2
is causing issues. Running around adjusting stuff but need the weekend so I can see it all better.
Edit - found a switch to manually turn the co2
injection on and one diffuser was like a soda stream. Would of been flooding tank. Reset it back. Got to find instructions for ph controller now.