Help! Deficiency or Lock-Out?

[BunkerMonkey]

I currently have a problem in one of my plants that is almost 4 weeks into flowering - leaves turning yellow starting at the tips, tips curled up, and brown spots. I don't know if it's a Mg or a K deficiency or if those nutrients are locked out. The other three plants are a different variety and do not show the same symptoms and they were all being fed from the same bucket. It's a "soil" grow in B'Cuzz HydroMixx using standard nutrients at 1/2 strength so it's hard to imagine that I've burned anything. I ran 4 gallons of my well water (ph 7.1 TDS 480ppm) through the "soil" (10 gallon Dirt Bags) and when I measured the pH of the runoff it had fallen to 5.5 and the TDS was 205ppm.

So does my "soil" need more nutrients since it actually LOWERED the parts per million of my well water? And it's obvious that I need to raise the pH higher than the 6.5 I was using to maybe 7.0 so as to make the Mg and K more available?

 

[CO Finest]

Try to get your ph up some.

 

[BunkerMonkey]

Thanks for replying CO Finest. Raising the ph is first on the list or there's no point in adding nutrients, huh? I forgot to mention that I first transplanted all four plants that my cousin gave me into Miracle Grow with six months of built in fertilizer because I thought I would have to leave them with my other cousin while I went to Florida to do some work so then when I got back to Michigan I could take clones and start in DWC. So there is a 2 1/2 gallon sized volume of that damned Miracle Grow potting soil in the middle of the 10 gallon Dirt Bags with B'Cuzz Mixx. The three Vanilla Kush are doing fine other than a little N deficiency because I am afraid of overfeeding them N and burning them again like I did in veg. It's the Epiphany(?) Bud plant that is suffering, but even while deficient or locked out it's buds are twice the size and stickiness of the Vanilla Kush so I have more in DWC vegging and want to keep the strain as happy as it was before in the same containers in veg and as happy as it's clones are doing currently in week 4 of veg.

Anyway, here's what's been happening....
3 gal well water pH 7.0 and 480ppm TDS in and outflow pH 5.4 and 340ppm TDS
3 gallon RO water pH 6.8 and 10ppm TDS in.....outflow pH 5.5 and 205ppm TDS
3 gallon RO water pH 6.8 and 10ppm TDS in.....outflow pH 5.9 and 885ppm TDS

I'm going to flush a fourth time. Be back in a half hour or so. Here's an enhanced photo of the problem. Could it be a Potassium problem too? -

 

[BunkerMonkey]

The third image down in the left column looks like what I have and says "Potassium Late Stage". I've been giving the plant General Hydroponics Grow/Micro/Bloom at 1/2 strength (600ppm pH 6.5 final) since veg except for skipping the GH Grow a couple of weeks ago which seemed to result in a Nitrogen deficiency that was easily corrected.

Waddaya think huh?

 

[BunkerMonkey]

Going by the principle that there's almost always more than one cause of a problem and from what I've read over the last few hours I went with the hypothesis that I had Lock-Out of Mg, ,P, K, Mn, Zn and a few other micro nutrients I continued on with what I have named "Flood and Drain Flushes".

Flushes 4 and 5 with pH 7.5 and 60ppm TDS brought the pH up to 6.2 and the TDS down to 360ppm so since I could get Flood and Drain Flush #6 in before the lights went off I added 1/2 strength GH Micro and Bloom for a TDS of 500 and adjusted the pH to 7.0 and dumped it into the 10 gallon Dirt Bag. The outflow was pH 6.6 and the TDS was 470ppm. Now all that's left to be done is to wait and observe. I keep pinching off the worst affected leaves since they won't recover from the necrosis and also it helps me determine if the problem is getting worse...and it has been for about two weeks. Hopefully this does the trick.

It's a little hard to see under just the supplemental UV-B lights but there's one of the nasty yellowing buggers in the lower left corner.

 

[CO Finest]

I have never grown plants in MG soil. I have read many many people having problems using it. You should be able to do a search on here for MG and find forum where people having problems that might be same.

 

[BunkerMonkey]

Hey CO Finest, yesterday I found good info about MG right here on 420 in a thread by Sticky. The MG section is a few pages down after all the other nutrients have been covered. Thinking back to January when all I had to use for fertilizer was MG, I was overfeeding this plant in comparison to the others because it could gobble the nitrogen up about 3 times faster and not show any signs of burn so I pushed the limits and no doubt built up a bunch of mineral salts in the core of the root ball and caused all the nutrients to get locked-out.

Nutes - What To Use & How To Use Them - Tutorial

The technique that should prove to be the most help in my case is the Emergency Flush which consists of cutting the main stalk of the plant and putting it in water for the last few days.

 

[CO Finest]

Awesome. that is good to know. Plants need different attention in different soils. Its about finding the sweet spot in each set up. The more info you leaner threw each grow will help passing on to others in need. I will keep a eye on yours to use as a good reference. When having salt problems good flush and some kelp solves that for me. I like old age kelp in all stages. I wish you the best keep in touch.

 

[BunkerMonkey]

I'm a big believer of passing on whatever I learn from success and failure as so many have done before me because without the experiences of others to learn from I'd still be growing like an amateur.

Also...the lights just came on and the plant didn't die "overnight" so there may still be hope.

If this plant stops having problems then I've learned a good lesson - there's usually more than one reason for a problem.

 

[BunkerMonkey]

UPDATE:
At this point in the grow (5 weeks into flower) I don't know if I'm going to see any improvement in this plant, but as long as the yellowing, leaf tip curling, and necrosis spots don't progress onto the newer growth (and it doesn't seem to be) then I'll be happy. My current hypothesis is that I had/have multiple deficiencies that appeared about 2-3 weeks into flowering because I wasn't checking pH after adding supplemental for budding resulting in a soil pH of around 5.4. This strain really packs on the bud compared to the other three plants and at that low of a pH Mg, Ca, P, K, and Zn just weren't available to the plant in sufficient quantity especially since I only add base nutrients to about 700ppm. The probable Zinc deficiency is odd considering it is available to plants at a pH of 5.4 but perhaps there was a reason - I had needed something to stake this girl up when I moved it to it's new accommodations because it wanted to fall over so I grabbed the first thing I saw that would do the job...a steel rod. I may be wrong but Zn does have an affinity for iron and maybe it was migrating over to that steel rod in the middle of that acidic soil. I guess it doesn't matter since I'll never use metal again to stake a plant up and I doubt that too many other people ever have or will either.

P.S. I snipped a nugget off her about 5 days ago and it's dry enough to smoke so this morning I so I lit up a small bowl and YEAH BABY! Evn uncured it's smooth and potent. The supplemental UV-B undoubtedly helped with the potency. Still mostly clear trichomes and with about 3 weeks to go yet but even dried out these buds are already as big as my big ol' fat thumb and dense and sticky. Just as a benchmark - according to local underground prices - this bud would fetch $10/gram and they would come back for more. Happy days ahead!