Hey @Stephane,
Yep, the pH probe is fine in the Grobo, as we dose the water soon after the distilled or RO water is added. (Even in the germination stage) However, if you are caught needing to re-hydrate your probe due to it drying out, don’t use RO or distilled. Think of it kinda like this…
You are in a large room with carpet, furniture, people and pets. The sound from your voice is absorbed by the room and at a nice understandable level when you speak. Remove everything from the room, and suddenly there are echoes and understanding you becomes much more difficult, eventually leading to madness. That’s kinda what happens with your probes rehydrating in ‘empty’ water. The probes lose their reference point due to changed chemistry in the probe itself.
Hope that makes some sort of sense…
Stephen