Deficiency? Excess? Ph?

[Grimmus]

Problem: leaves started showing orange spots on random fan leaves. Then large brown spots in-between veins. Some leaves turned crispy with curled up edges

Medium/grow method: larger 5 gal fabric pots. With ff happy frog

Feed: and supplements used: tps OAC cal mag and AN ph perfect micro grow and boom. I presoaked soil with an aerated compost tea( shot glass of mollasses, 3 cups worm castings, and white shark myco) sprayed seedlings with distilled water and gave small sips of R/o with a 1/4 strength dose of calmag for the first 3 weeks. At 21 days I mixed 1/8 of a dose of AN micro grow and bloom and used a pinch of baking soda to bring ph up to 6.5. and fully watered. I noticed the ph of run off to be about 6.0. I upped the calmag to 1/2 strength for the next 2 watering followed by a 1/4 dose of AN on day 28. I started noticing the symptoms around this point. I assumed it was calmag and upped the amount of calmag for the next watering to 3/4 strength at day 32. Ph after aerating for 48hrs was 6.8. Watered till run off and run off was testing 5.5. I just watered again this morning with full strength calmag. I have slightly under 1/2 strength AN micro grow and bloom aerating in the barrel for Monday morning.

water source:
R/O water 0ppm
Strain/age:
Barney's farm purple punch autos and amnesia express by pheonix seeds 34 days old I also have6 red poison and 3 purple haze autos that don't have the problems yet.
light used:
Growcraft x6 600 , 2 ts1000s, and 2 generic blurples at 18-24 inches
Climate:
Temp runs between 75 and 80f humidity has been low around 40 percent but recent weather has neen keeping it around 55rh
Additional info

 

[Bruce Campbell]

I suspect low K / high Ca.

From the leaves themselves, it's hard to tell - it looks like it could be a P, Ca, or K issue.

FFHF has some N, P, and Ca included but does not have any K. FF nutes typically account for that, but it can create problems when using other nutrient lines.

Typical practice is to provide K:Ca:Mg in a 4:2:1 elemental ratio. All three are cations and compete for uptake in the root zone. Too much of one element can reduce uptake of the other two and lead to deficiencies.

As far as suggestions:

1) I'd cut out the cal-mag. FFHF has a good amount of Ca, which should last most of the grow and help offset your use of RO. If you run into Mg issues later, you can use epsom salts for a feed or foliar application.

2) I'd take a look at how much K the AN nutes are providing, and perhaps try to increase K.

3) Sodium bicarbonate (baking soda) can be used in a pinch, but I would find another pH adjuster. With repeated use, the sodium can build up in the soil. Most horticultural pH-up products are K based (which would likely help you in this situation). Personally, I use Bloom City Silica Boost as a pH-up, which is a fulvic acid / potassium silicate based product.

4) I wouldn't pay too much attention to run-off pH - it depends on a number of factors, which makes it difficult to draw any conclusions from single readings (unless you're doing straight hydro with inert media and no CEC).

5) Longer-term / next grow, I would switch to either a fully organic (soil & amendments) or fully inorganic (coco or peat with mineral salt nutes) approach. Combining the two means that you have to guess at the availability / mineralization of the organics over time when planning out feed levels.

6) I also usually calculate out elemental ppms (guide here) before deciding how much cal-mag to use. Since the point of cal-mag is to bring your cations into balance, the correct dosage depends on your specific media/water/feed. I.e., the recommended doses on vendor labels for cal-mag are very generic and can be a poor reference point.

 

[Grimmus]

Thanks for the great info