Lowering soil pH necessary? Plants dying, help!

[kanvict]

So I started noticing what seemed to look like Mg deficiency on my plants but a more experienced grower pointed out that it may indeed be Mn deficiency from my high alkaline tap water (pH 8.1, 155 ppm). By this time, I had already top dressed my plants with pellet unhydrated garden lime to supplement Mg and raise pH. I'm in FFOF soil which has a pH of 6; I was told the soil would buffer the pH so it wouldn't be necessary to adjust the pH of my tap water... however, there's clearly an issue and my soil is now at a pH of 7.4 confirming that it is indeed a Mn deficiency which is starting to spread.

So here's my question: should I add something like peat moss to make the soil more acidic (considering FFOF already has a pH of 6) OR just start watering with pH adjusted tap water (assuming the soil will eventually get back to the optimal range since the water will be adjusted correctly) OR water using RO / Distilled Water with no trace minerals at all?

Any help would be appreciated!

 

[canabinerd]

A bit more info would be nice, including a picture. When did you last water? What stage of growth is the plant in? Temperature and humidity? How often are you watering?

 

[greenergrass]

pictures are helpful sounds like you need to do a flush if the ph is wrong excess nutrients can build up as they are not being taken up by the plant, the soil could have plenty of a certain nute and the plants roots cant absorb it because the ph is wrong

 

[KingJohnC]

I would flush your pots with pH adjusted water with at least twice the volume as pot size or until your input pH is the same as your runoff pH. You want pH 5.8 for hydroponic and soiless (peat moss and coco coir) and pH 6.5 for soil.


here is a nutrient availability chart

here is a cannabis leaf deficiency chart

here is the Cannabis Plant and Pest Problem Solver and the Plant Abuse Chart

Cannabis Plant and Pest Problem Solver - Pictorial

Plant Abuse Chart