Deficiencies and pH meter accuracy concerns

[James427]

Hello all I'm looking for some advice on wants causing taco effects on the leaves and how much nutes my plants need. I currently have 6 plants in 1 gal pots. They where transplanted into said pots about 10 days ago in FFOF medium with 30% perlite. Now my plants are showing signs of likely heat stress on 2 the taco effect on upper leaves and one plant has yellowing in the edges of taco leaves as well as curling upwards. I think it's heat stress because it was 90+ degrees in the tent a few times and dropped in the 60s right after causing serious heat stress. Also RH has been everywhere but was into the 20% range during the high heat. I also am noticing a few plants are showing nitrogen deficiency on the lower growth and some phosphorous deficiencies on lower growth as well. I looked on grow weed easy and the phosphorous deficiencies matched 2 of my plants lower foliage problems perfectly. Right now I have FF nutrient trio big bloom, grow big, and tiger Bloom. I also have cal mag I add small amounts of because I am planning on running RO water. Now they are 36 days from sprout and about 10 days in the FFOF soil. Would a light feeding with the FF nutes and cal mag be OK or is the soil possibly still to hot? Also I have this PH meter: Hanna Instruments HI 98107 pHep pH Tester, with +/-0.1 Accuracy, and I'm concerned about accuracy. It has been calibrated and reads 6.2-6.7 going in and runoff is usually 5.7-6.0. I want to go crazy on flushes and pHing water but I'm worried it's not accurate. I still on the water but I haven't been paying to much attention to the runoff pH. It kind of rises slowly then stops, then rises more at random and I feel like it's not accurate. Maybe I'm over reacting but I though pH meters when right up to the reading then stopped and didn't stop and go and stop ect. Other wise my foliage seems very healthy. It's a great color and one of my plants is showing female pre flowers! Hope I don't kill it lol. Anyways I'm gonna try a light feeding I guess I just worry about pH and nute burns alot so I have been slacking alot with feeding. Anyways I'll update after I feed to see how it goes.

What strain is it? Unknown. Reggie bagseeds
Is it indica, sativa, hybrid? What percentages? likely a indica strain unknown percentages.
How many plants? Six plants.
Is it in vegetative or flowering stage? Vegetative.
How long in vegetative state? Not sure when seedlings ends and veg starts but probably about a month.
Indoor or outdoor? Indoor.
Soil or hydro? Soil FFOF.
If soil what is in your mix? FFOF with 30% perlite.
If soil what size pot? 1 gal.
Size wattage of light and how many? 1 600 watt MH on 50% power.
Is it air cooled? No.
Temperature of tent? 65-75 lights out and 75-85 lights on. Spikes into 90s few times.
RH of tent? 30-45% will drop below 30 when hotter.
pH of medium? pH is 6.2-6.7 going in and 5.7-6.0 runoff.
Any pests? None.
How often are you watering? Every 3 or so days. Depending on when the pots feel light enough.
Type and strength of fertilizers used? FF nute trio big bloom tiger Bloom and grow big. Very light feedings when I see deficiencies. Usually a few milliliters each at most per gallon.
Size and square footage of room? Tent is 3x3x6.1

I also have a 6" fan now pulling cold air from central air vents in and venting hot air into room through a duct. When the ac's on temps will drop below 80. Any advice on if I'm over thinking and under feeding would be greatly appreciated.

 

[TheFertilizer]

I THINK I have heard that FFOF can be a little on the acidic side for cannabis, but also read thst amending it with 30% perlite will help. You might consider adding an ademendment to raise the soil pH. I doubt your meter is inaccurate if it's all calibrated but one thing to keep in mind is that pH can actually change rapidly in solution depending on chemicals and biological makeup. I think you need to look up how to amend it to raise the pH though. 6 is a little low and would make sense for lockout.

With one gallon pots it sound like you might be over watering a little bit. Can you check your roots? I would make sure they're not rotted from staying submerged too long. Do your plants look over watered at all? They will look like the leaves are too heavy and point down while the stems stay mostly rigid. Hard to say with all included factors but every 3 days sounds a little long.

If it's 26 days above ground it's just now entering vegetative growth. I think you're right about the heat stress but the yellowing could be an N deficiency, though they usually show on a lower leaves first. A few mL doesn't sound like much to me but FFOF is really nutrient packed so I don't think you should need to be supplementing right now anyway.

So my advice... Stop feeding nutrients and focus on the soil. If you have the cash by a soil pH probe. Look up how to raise the pH, I think lime will do it but I am not sure. See if you can water a little less, and check your roots for health and vigor.

Keep in mind that an over abundance of some nutrients can lock others out.

 

[James427]

Thanks for the reply. I'm definitely going to get some dolomite lime asap. All of my runoff pH reading where around 5.4-5.8 way to low for me. Im wondering though if it's really going to far with the pHing because I have read multiple times from experienced growers (such as fuzzy duck) that if you what the way this soil works with a probe it drops real low while wet and comes back up slowly in pH as the plant drinks to give it a full range of nutes and he stated he hasn't messed with this PITA pH crap at all and is doing fine. Any ideas on this? I'm using FFOF with 30% perlite but I'm wondering if it's even worth bothering with pH at all.