Rapid ph drop in DWC using canna aqua

[Gurifg]

Hi all
i currently run a dwc system and I’m 4 weeks into veg on an OG Kush, my issue is I can’t seem to stabilise the ph, it drops from 5.8 to 4.7 within a 8hr time frame.
I run the canna aqua line.
canna aqua a&b
cal/mag
rhizotonic
cannazym
my ec reads 1.0 - 1.2
and I set my ph at 5.8 - 6.1
I run a cooler so res temp is constant 18•c
room temp is 25•c
Humidity is 30% which is low but I think should be ok. (Humidifier in the post)
plants look ok I think, maybe slightly slow growth?
roots are white and health looking,
any ideas on how to stabilise ph or why it drops so rapid?
here’s a couple of pics.

[YYCannabis]

To help raise the humidity, which you need to do, is place a tray of water in front of a fan. Maybe just hanging some wet towels in the tent would help too. I’ve added a pic of a chart that is something you should keep handy when checking on your plants 😉 At your RH of 30% it would be beneficial to lower your temps if you can. Your VPD is way off the chart (in a bad direction) and is probably making your plant unhappy.

Check your res for pH and EC and monitor how much the water level is changing, then refer to the chart. It might help point you to why the pH is crashing.

Cheers
YYC