Magnesium, Nitrogen, or pH problem?? please help pics included

For background information: 6 northern lights plants, FF Ocean Forest Soil, only nutes I am using atm is FF Big Bloom to help with nutrient lock up. Every plant looks great except for the one we are talking about. I am watering plants with filtered water every 2-3 days. Plants are under 250watt MH currently, about to switch to 12-12 HPS to get 2-3' plants (I hope).

Based on what I have read my problem is most likely MG or N, but I have read it could be due to lockout from a pH problem. I have a digital pH meter at my university used for chemistry (I am competent using it) and was wondering what the best way to test pH of a soil medium is. I was going to take some soil, put it in a large flask w/ DI water, shake it vigorously, centrifuge it, and then measure the pH of the water. Will this work?

Pics



click for enlarge


My problem is only hapenning on the new growth of the plant, as can be seen from the pictures. And I have read that for many nutrient problems it typically can effect the whole plant, which is why I thought it may be a pH problem.

Unless I hear differently today or tonight, I am going to take a soil sample to school with me tomorrow and test the pH by the method I mentioned as I do not have a soil pH probe.

Any advise would be much appreciated

Lay off the nutes first off, and second make sure your shaking the nutes before you put them in your system or container. It looks like they were short on nitrogen, then you nuked them with N. I would flush it.

magnesium.......... and possible ph.... what is ur ph? but mag. for sure looks like.. got any cal/mag or epsom salt by chance?

def looks like mag. mag issues start at the top, N issues start a the bottom. It could be ph lock out though.

West Coast Medicine said:

Lay off the nutes first off, and second make sure your shaking the nutes before you put them in your system or container. It looks like they were short on nitrogen, then you nuked them with N. I would flush it.

Click to expand...

Negative, nitrogen deficiency first shows up on the older growth, not the newer. This plant is a prime example of magnesium deficiency. I would mix up some epsom salts per directions on the bag and water the soil with it. You should see improvement within a couple of hours, as epsom salts are readily absorbed by the plant.

Your PH would really need to be out of whack to be causing this.

EDIT: Damn, two answers while I was typing up mine.... But yeah, it's mag def.

sine143 said:

def looks like mag. mag issues start at the top, N issues start a the bottom. It could be ph lock out though.

Click to expand...

mag. usully starts at the bottom to bro

thanks alot, I do not know the pH of my soil I was going to test it tomorrow.

If the pH would not cause what is shown I will go ahead and try epsom salts, are the ones available at target/walmart in the bath section the same as those used for plants?

zykster said:

thanks alot, I do not know the pH of my soil I was going to test it tomorrow.

If the pH would not cause what is shown I will go ahead and try epsom salts, are the ones available at target/walmart in the bath section the same as those used for plants?

Click to expand...

typicly you wanna rule shit out before you just go adding shit.... but im pretty confident thats a mag. def. and yes that epsom salt aka magnesium sulfate is the one .... dont worry about the ph too much anyway cuzz the epsom salt will fix that.... you wanna use a teaspoon per gallon

thanks a lot theexpress that was exactly what I was wondering, epsom salts it is