Need help with a reoccurring problem

I am having a problem that appears to be a magnesium deficiency where the oldest fan leaves develop spots that spread and eventually consume the entire leaf. I’ve grown a few different strains, most show the symptom as seedlings, some worse than others, some grow out of it. One plant, a Big Bang is the worst. I flowered it besides it having the problem cause I had the room in flower room, the pictures below show the progression. All are grown from seed, I give no nutes for the 1st week, after that I slowly raise the ppm. The PH I monitor every day and keep it close to 5.8. I use GH 3 part with Cal Mag and RO water. The large plant had the problem at the start but is very healthy now and is in the same bio bucket system as the Big Bang. The other picture is my latest seedling a Joey Weed strain in a DWC under cfls, PH 5.79, 330ppm equal parts GH micro, grow, bloom & Cal Mag and a drop of superthrive. Temps stay in the 70s, RH is 45%. What could be causing this?

The Big Bang













A Joey weed showing the same signs



The Legends strain that grew out of it

Sounds like you've got everything in good shape.....what's the temps of your water? That's about the only thing I can think of that you didn't cover.

The DWC is 73 degrees and the bio bucket system is 68 degrees. I'm thinking the Big Bang is just a bad pheno but that doesn't explain it happening with the other strains. I also have a Big Bang in soil that is not showing this problem.

You seem as though you are keeping track of things very well....i'm afraid I'm not familiar with the GH 3 part so can't say if your ratios between them are correct. I certainly can't see anything you are doing wrong there.....everything seems spot on.

Stricly a guess imo....but I would think this issue has to be in the ratio of your nutes unless there is something else going on. If there is....I sure don't see it anywhere.

Good luck....I'll check back and see how it's going for you.

stop using the superthrive, does not work in hydro and cause have a bad reaction with things.

When you mix your gh 3 part are you mixing the micros in first?
They look like the mixture was not mixed right or something.
They also look burnt to a crisp or something.

After half the day is gone do you check there ppm's and pH?
After you add nutrients?
Do you calbrate your equipment every 2 weeks max?

Actually I've never had a problem using ST in hydro.

you may think so, but do some googling on superthrive and hydro when growing cannabis.
You will find out what problems it can cause, not all strains can handle it. It causes a buildup and the bubbling of the buckets somehow causes a chemical reaction with superthrive that can or sometimes does not cause a gooey like substance to appear.

Hey Stitch, thanks for looking in. I didn’t start using the superthrive until after I started flowering the Big Bang. Although I did use Rhizotonic.
I have always added the micro first, but I may be guilty of not mixing well after adding nutes. That may explain the problems as seedlings but why do the leaves on the Big Bang continue to deteriorate in the bio buckets while the legend plant looks awesome? They are the same age.
I check the PH at least twice a day. After a reservoir change in the DWC the ph drifts up to 6.1 or so and I adjust to bring it down slowly to 5.8. I do a two point calibration on my meter every week or two.

Easy, they are both different strains, so when you have different strains in the same system, unless you know they are the same in nutrient care and such it's not good to grow out different strains in the same hydro system.

Each strain can take different amounts of nutrients, pH ranges and heat stress light wattages and so forth.
So when you get 2 different strains, one may be more hungry or one may be more picky and can't take the high nutrient amount as the other, so you are playing tug a war the whole time, so not only do you cause you to have less yeild, because one has to win and one has to lose; but you have to try to find a median where both plants can be somewhat happy and sometimes that's not possible.

So that is why it's a bad idea to grow 2 or more strains in a setup like you have, unless you know they have been grown out before and are near the same nutrient requirements and can be grown in the setup together.

pH drifts up high, because the plants are removing nutrients from the water, you want to keep your pH stable by using pH adjusters like up and down, as for the PPM's
You NEVER want to up your ppms to try to control the pH, doing this burns your plants, this is where pH up and down come in handy,
so you use your ppm meter to find out how much nutrients they took out of the water and add accordingly and then test the ph after it's been mixed up. If the pH is not correct you use pH up or down to fix the problem depending on if it needs to be higher or lower.