Hi Jon,
this issue could be due to the changes in carbon enrichment. Your spraybar adjustment to give greater surface movement will be creating increased gas exchange, and your drop checker corroborates this with a blue green rather than light green colouration for lights on....you most likely need to inject at a higher rate now to compensate and to give you the light green colour for lights on as this is when the plants need it most.
Cheerio,
Ady.
Hi Ady, I was hoping to reduce co2 to be honest. I know you shouldn't read to much into bubble count but I'm at 2 bps at the moment. I was hoping to slowly reduce that to around 1 bps. With regard to the dc - what about the time delay? if it's green 2 hours after lights on would that not be the actual reading 2 hours earlier? Or does that only apply when you first fill the dc with new solution? fyi I switch the co2 on 2 hrs before the lights come on. Also dosing liquid carbon as a belt and braces approach.
Thanks for your help chaps