Help with imbalance.

I have a white widow big bud plant that is having a problem with some necrotic spots developing on a few leaves. I am using AN sensi grow pH perfect in RO water. It is currently at 1/4 strength with cal-mag, b52, and hydroguard. At 1/4 strength the pH usually sits at around 6.1 and PPM around 950. I figured this was a calcium deficiency so I doubled the cal-mag and added 10mL to my 4L reservoir during a nutrient change a few days ago but it doesn't seem to be stopping. This plant is about 2.5 weeks from seed and is just under a T8 shop light that is on 24/7. This issue has started at the bottom of the plant and is slowly moving up. Despite this problem this plant continues to grow pretty well and is putting on new growth and roots. Room temp is 77F and RH 50%.

The first picture is a fan leaf on the 3rd node and representative of how the leaves start to become affected. The more severe damage is from a leaf from the 2nd node.

Is there something else going on with this plant?

How are the roots? That's the first thing I would check. I was having the same issue as well and I started to use vitanimo, my plants have never been happier. It's fucking pricey and am trying to source a similar cheaper product (amino). The last run I did was probably the healthiest yet with no blotching or yellowing. I hooked up chilled water, ran hydroguard, cheap no name base nutes, vitanimo, and nothing else. It actually kept its big leaves right till chop with no fading, first time for that, I actually stopped using the vitanimo at the end to see if it was hindering the finish.

Roots are growing and look good. The B52 is some old stock that I was just trying to use up so I may cut that out and see if it is somehow causing a problem. I didn't plan on replacing it but I will take a look at Vitamino. I feel like it is going to continue since today I noticed there are a few tiny spots on a previously unaffected leaf.

SpookBud said:

Roots are growing and look good. The B52 is some old stock that I was just trying to use up so I may cut that out and see if it is somehow causing a problem. I didn't plan on replacing it but I will take a look at Vitamino. I feel like it is going to continue since today I noticed there are a few tiny spots on a previously unaffected leaf.

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I use well water and the reason I tried vitanimo was a few discussions about using amino acids to allow for the uptake of calcium and magnesium that otherwise is not available. Not recommending it but it did work in my setup.

Just in case anyone stumbles across this my problem was caused by using AN ph perfect and cal-mag together. I don't know why it affected one strain more than the others (1 had very minimal issues just now showing up and the other is perfect) since everything was the same for all of them. The bottle says use with RO water and I was so used to adding cal-mag to all RO applications I went ahead and added it in and somehow caused a calcium lockout very early into veg. Last rez change I just added AN ph perfect and hydroguard to my RO water and they are looking great now so hopefully that is the last of any issue with this product line.