Magnesium problem

Question from a fellow grower:

According to all the research I can find, I have a magnesium problem in my water system. I found out that Epsom Salts is a good cure. 1 Tsp per gallon. But there is no mention of how frequently. When is the nutrient depleted again. I have a 14 gallon system. I discovered today that this appears to be increasing not decreasing. Over a period of 10 years previously, I never had any water issue. My PH is 6.5. Any suggestions?

I would say this is your issue. PH should be from 5.5 to 6.2 with the sweet spot at 5.8. Your locking out the Mag is my guess.

Yup that would be where ur mag problem comes in to high of ph need it down to 5.8

I have been growing Northern Lights for 15 years from various cuttings in Hydroponics. My results were excellent. 4-6 plants produced 18-22 oz. I have never had any problems from water to nutriments. I used straight well water. I never tested the water for for ph or anything else. According to the lasted book from Rosenthal, my 6.5 is correct for ph and hydroponics.

What was never addressed was using the Epsom salts. I asked if anyone have scientific information about it’s depletion and how often to use it.

It still could be the seeds and the feminized seeds themselves.

Any other ideas are welcome.

Thank you.


Depletion of magnesium can be variable. Depends on medium or if you use LED lights etc.
I add 1/4 teaspoon per gallon every watering/feeding. This seems to work well. In hydro it is a little over a gram per gallon.
Ph of 6.5 definately on the high end for me. I stay at 5.9 or as high as 6.2