Onset of Mag. deficiency?

[Muskellunge218]

I'm rounding off week 1 with my speed seed Auto Blueberry and Diesel grow. 2 or 3 days ago I noticed a lime green band making its way down the set of true leaves on each plant, more so on the Blueberry. Soil is Black Gold seedling mix (70-80% Canadian sphagnum peat moss, perlite, dolomite lime, and yucca extract). They're under at MH 600 watt LED reflector. Room temp has fluctuated between 76-83 degrees Fahrenheit, and RH between 35-40%. Since day 1 they have only been receiving Ph'ed tap water (5.8-6.1) that has sat out. I unfortunately cannot provide soil PH. I included pics as well as a screenshot I took from the diagnostic criteria for a magnesium deficiency. Thanks, please let me know if I can provide any other information.

 

[elsamurai]

at that age they should get all they need from the cotyledon's. try raising the water ph to 6.5-6.8. I start the cal/mag around day 10-14. are you running just the grow side? for me,its been more of a problem when the bloom light is on and at that age the veg side is more than enough. start at 1/4 strength and work up to full.

 

[Muskellunge218]

at that age they should get all they need from the cotyledon's. try raising the water ph to 6.5-6.8. I start the cal/mag around day 10-14. are you running just the grow side? for me,its been more of a problem when the bloom light is on and at that age the veg side is more than enough. start at 1/4 strength and work up to full.

Thanks for the reply E. Im am afraid I am unsure of what you mean by, "grow side, the bloom light, and the veg side". What supplement are you referring to when you suggest starting at 1/4 strength? Again, thanks for the reply.

 

[elsamurai]

oh maybe my mistake. is that metal halide or mars-hydro? lol. the mars-hyro reflector has a switch for grow and 1 for bloom.
I've been using General Hydro CalMagik for the mag def. I always seem to need more cal though

 

[Muskellunge218]

oh maybe my mistake. is that metal halide or mars-hydro? lol. the mars-hyro reflector has a switch for grow and 1 for bloom.
I've been using General Hydro CalMagik for the mag def. I always seem to need more cal though

Aha, thats what I thought you were referring to. MH= Mars Hydro. And my unit in particular does not have a veg/bloom switch. It is a full spectrum LED. Would that be your opinion of what the light green is, Cal/mag?

 

[Waira]

musky-- ...at this young stage, it can't be a defc., as El Sam' mentioned,... BG soil does have a charge of nutrients in it already, but I don't think it's very strong, even for auto's.... but I might be wrong, plus auto's a notoriously variable in their tolerances for this, strain to strain,... soil pH is everything, key to preventing and fixing issues,... without it, diagnosing and taking corrective measures is all guess work, as likely to harm as to help! The symptoms on those leaf tips looks like early nute burn, or could be off-pH,.... how did you get pH's on your water, a test kit, or meter?

 

[Muskellunge218]

musky-- ...at this young stage, it can't be a defc., as El Sam' mentioned,... BG soil does have a charge of nutrients in it already, but I don't think it's very strong, even for auto's.... but I might be wrong, plus auto's a notoriously variable in their tolerances for this, strain to strain,... soil pH is everything, key to preventing and fixing issues,... without it, diagnosing and taking corrective measures is all guess work, as likely to harm as to help! The symptoms on those leaf tips looks like early nute burn, or could be off-pH,.... how did you get pH's on your water, a test kit, or meter?

Both test kit and digital meter. On avg, if I'm using tap water, what PH should I be shooting for? Like I mentioned, I am adjusting and watering at 5.8-6.1.

 

[Waira]

..ah! -then you can test your soil pH using the run-off method, which is better than nothing,... it can give a decent estimate, if done right, but is highly prone to measurement errors otherwise,...check this link, and follow directions; you can even use soil from the bag instead, since it so early on, and you've not added anything in yet, right?... https://www.autoflower.org/threads/another-quickie-reference-for-run-off-testing-and-ph-estimation.41733/
... what's the water pH without adjusting? 6.5-7.0 is fine generally,... Do you have any idea about how hard it is (mineral content), a ppm reading by any chance? this is relevant to whether or not to bother pH'ing it in the first place,.. I'd say you're making the water too acidic right now,... and I suspect the soil is too acidic as well,....

 

[Muskellunge218]

Thanks for the input Waira. I will commence a run-off test tomorrow morning when they wake up and will need a watering. And that is one the purchase I have considered making is a digital PPM meter, I unfortunately could not tell you how hard/soft the water is. Would that be a variable i could eliminate if I opted for R/O or distilled as opposed to tap?

 

[Muskellunge218]

Just finished my first run off test, I think I got the gist of things. My normal irrigation water was sitting at 6.5. I saturated the soil as per the instructions, waited and hour, then ran the distilled water through the plants. The run off read at 6.1-6.0. That leaves my soil PH sitting at roughly 5.8. How do I rectify and neutralize the acidity content? Just correct by using less acidic waterings?