I am running an Aero/NFT scrog and I am having leaf problems.

About 2 weeks ago the pH was hitting 7 daily and I was having to add crazy amounts of pH down, got it stable about 5 days ago, and this is how the leaves on the plants look now (see pic below).

What I need to know is if this is a magnesium deficiency, and if it is, how much MgSO4 should I add (epsom salt) per gallon of water, and how often should I foilar feed to fix it?

Please help me, I'm in need.

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Looks like an iron deficiency to me. "----Iron (Fe) is a key catalyst in chlorophyll production and is used in photosynthesis. A lack of iron turns leaves pale yellow or white while the veins remain green. Iron is difficult for plants to absorb and moves slowly within the plant. Always use chelated (immediately available to the plant) iron in nutrient mixes.-------"

Miracle Grow in a spray bottle should do the trick IMO.

Thanks for the input!

Are you flowering or vegging? That looks more like a nitrogen def to me. Which is VERY common in the flowering stage.

I just made the switch to flowering, about 10 days ago now. I'm pretty sure that its some kind of lockout, so I'm flushing with Clearex as I write this. I'll then add sensi-bloom nutes and keep the pH stable and hopefully it will correct itself in due time. We'll see (keeps fingers crossed).

Google is your friend. There are plenty of sites on the web that contain FACTS based on scientific research regarding nutrient deficiencies in cannabis. Here's one: "Iron is naturally plentiful in most soils, and is most likely to be deficient when the soil is very acid or alkaline" and you've been having Ph issues. Here's another one: "It takes less N than other nutrients to toxify the soil; hence there is less margin for error when using N. Too much N changes the osmotic balance between plant and soil." Do you really want to risk overdoing it on the N when your symptoms say you need iron? "Symptoms of iron deficiency are usually distinct..... the leaves are chlorotic between the veins, which remain dark green and stand out as a green network."

I'm certainly not an expert, my 25 years of growing experience has been by the trial and error method. But when I do have an important (potentially crop threatening) question I prefer to consult scientists rather than a bunch of potheads. No offense intended to my fellow potheads.

Here are 2 websites that have full lists and comprehensive descriptions of every nutrient deficiency you can imagine

http://www.greenmanspage.com/guides/...disorders.html

http://marijuanagirls.com/MarijuanaF...uide.html#c9_4

The attached pix are from previous years grows. When you get buds the size of your own arms year after year, grown outdoors in Michigan of all places, it's hard to disagree with the research scientists.

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Easily the best advice I've seen on these forums, thank you sir. +rep

Bookmarking both those links too

+ rep for putting photos of yourself ???? up.

nah, for the links and the advice.

nah, i gave him rep for that