One week into flowering - brown spots

[tagametHB]

After some research I'm not sure if this is nute burn or maybe a magnesium shortage? Second cycle of plants, so I'm still "green". Anyone recognize this? I'm growing in 5 gallon buckets DWC, fox farm nutes (following the fox farm instructions).

New growth looks great. Maybe 40% of leaves have some form of this, and 5% look like this. Plants are 5 weeks old.

 

[purplephazes]

A magnesium deficient plant is identified by intervenial chlorosis, necrosis, and eventually a lockout of plant nutrients. The problems starts at the bottom of the plants and works it’s way up.

Chlorophyll has the same structure as Hemoglobin, except that it has a magnesium atom in place of the Iron atom. Chlorophyll is how plants make sugars to feed the process of building ATP through the Krebs cycle.

Treating with an Epsom salts mix will clear this right up...yet Nutrients lock out( or don't get absorbed) when the water PH is too acidic or basic. Most plants perform the best between the range of 5.5 and 6.5. Mostly plants grown in soil or soiless mix will thrive around the 6.5 range and most hydroponically grown plants will thrive with a resevoir PH in the 5.5-5.8 range. This is only a general guide, each mj plant has a specific PH that it performs the best at. It is up to you as the grower to be savvy enough to know when you have found the correct PH for your garden. peace and take care !