One of the good things about using RO is you can very easily add 20% Tap water as a buffer and still have kick-ass water.
Creeperpark Got the system, but couldn't install it yet since I need to find the right adapter. The bad news is that there is another deficiency. I assume that I can avoid them in future grows with the RO since the pH wont be out of whack, but not sure how to proceed here as the neighbouring plant looks nice.
The plant with deficiency had a run off at 6.6 pH, the healthy one is at 6.4 pH. I added a little bit of calmag to the sad one (1ml/L).