Plants has some yellow spots & some tip burn

Hi,
This is my first grow. I'm growing 2 white widow autos and 2 blueberry autos in 5 gallon pots, in a mix of gaia green living soil and fox farms ocean forest soil. They're under a 600w mh (light is about 16-17 inches from tallest plant top) for now until the last one goes into flower, then it will be switched out to a hps. I have a square 18" fan mounted on the wall above the canopy pointed at the light on high and a 12" oscillating fan on the floor on the middle setting. I water them about every 2-3 days or so with water in the ph range of 6.2-6.7. I have given them 1tbsp of gaia green 4-4-4, which is below the suggested amount. They're all in preflower except one that was started later due to a seed not popping. These spots just started showing up, but they don't seem to be effecting the plants health too much yet but i want to figure out what it is so i can correct the issue. Anyone have any idea what this could be? Deficiency? Wind burn? Overfertilization? Thanks in advance for any help.

Your lights to close and especially for such a small plant but I don't use mh so can't get specific. The last photo is from some liquid getting on the plant under the lights I bet.

shawnery said:

Your lights to close and especially for such a small plant but I don't use mh so can't get specific. The last photo is from some liquid getting on the plant under the lights I bet.

Click to expand...

Thanks for your reply. Everywhere i read about the distance for the light has a range of about 14" being the closest, 16" being like sunlight and 25" being the maximum distance you want. I have been slowly trying to find the "sweet spot" for the light. I'll move the light and monitor for any signs of heat damage. But maybe i'll have to move it up a bit.

Whole plant pics

I forgot to mention, I'm doing LST. Spots are on the two on the right. The last photo in my first post was the bottom right. All other photos were the top right.

I see what appears to be the onset of a magnesium deficiency in your first pics, but that has nothing to do with the little yellow marks, which in my opinion, may be due to some water getting on the leaves or touching the wet soil and burning a bit? Plants seem good otherwise. Just watch that yellowing between the veins that i see in pic #...4814. Get some cal-mag or epsom salt.

Blitz35 said:

I see what appears to be the onset of a magnesium deficiency in your first pics, but that has nothing to do with the little yellow marks, which in my opinion, may be due to some water getting on the leaves or touching the wet soil and burning a bit? Plants seem good otherwise. Just watch that yellowing between the veins that i see in pic #...4814. Get some cal-mag or epsom salt.

Click to expand...

Thanks for the suggestion. I thought so about the magnesium too, but being new to it all, it was hard to identify with certainty. If i use epsom salt, how much would i use? Do i dissolve it into ph checked water then just water the plants? Also do i have to add some sort of calcium to the Epsom salt?

MarijuanaMama89 said:

Thanks for the suggestion. I thought so about the magnesium too, but being new to it all, it was hard to identify with certainty. If i use epsom salt, how much would i use? Do i dissolve it into ph checked water then just water the plants? Also do i have to add some sort of calcium to the Epsom salt?

Click to expand...

If you're using tap water, then calcium may not be needed in extra doses, provided that you have enough in your regular nutes. For epsom salt, i would add the equivalent of 1/2 teaspoon to the gallon of water for now. You can add it before or after ph-ing the water as epsom salt has no effect on ph.

Blitz35 said:

If you're using tap water, then calcium may not be needed in extra doses, provided that you have enough in your regular nutes. For epsom salt, i would add the equivalent of 1/2 teaspoon to the gallon of water for now. You can add it before or after ph-ing the water as epsom salt has no effect on ph.

Click to expand...

Thanks very much for your help. I will try this