Water stained heads as well as bacterial blotch mainly indicate evaporation problems. However, the cause is different.
Where insufficient evaporation over a longer period of time is the main cause for bacterial blotch, water stains are mostly caused by unstable evaporation. With bacterial blotch the solution can be found in the area of air movement and climate control.
With water stains the use of the climate computer could be the culprit. Often the first water stains already appear during pin heading and when the1st flush is developing. This is mainly caused by manually correctly the climate computer in too large steps during the period in question. Especially during pin heading, evaporation is at such a low level that even the slightest changes in air temperature RH CO2 or fan position can have a huge effect on the stability of evaporation.
Manually adjusting climate settings is not accurate enough so is often the main cause of the appearance of water stains during this stage. It’s far better to (automatically) set all climate changes very gradually during pin heading and growth.
Jan Gielen, Specialist climate & energy, C point