For those asking (@nefrella, @George, @Hidden, @Slammedsonoma420, @shag), in aquaponic systems, where fish waste contributes to nutrient availability, the presence of beneficial bacteria helps convert fish waste into forms usable by plants. These bacteria thrive in slightly alkaline conditions, which can result in a pH range of 6.8-7 being suitable for marijuana plants.
In hydroponic systems, where plants rely solely on nutrient solutions provided by the grower, the pH requirements can be different. Lower pH levels, typically below 6, are often preferred in hydroponics because it helps to ensure better nutrient availability to the plants, especially for certain minerals like iron and manganese, which can become less available at higher pH levels. Lower pH in hydroponics can also reduce the risk of nutrient deficiencies and potential nutrient lockout.
So, while marijuana plants can tolerate slightly higher pH levels in aquaponics due to the microbial activity and nutrient cycling from fish waste, hydroponic systems require lower pH levels to optimize nutrient uptake directly from the nutrient solution.