Slight N toxicity. Flush or ride it out?

[Benjidubwise]

Greets x
I've got 3 gorilla autos from Royal Queen Seeds in the tent at the moment. 2 are on day 19 & one is on day 15.
They are all doing pretty well m but I noticed the larger of the 3 has some slight clawing on the new growth from the apical meristem and the very tips of the newest growth are yellow.
Given how green the leaves are, I'm fairly confident this is a slight nitrogen overdose.
It's strange it's only affecting the largest of the 3 at the moment.... I would have thought a bigger plant would be able to handle more N??

I'm growing in Bat Special & using biobizz grow & heaven. I'm also using a kelp extract & a bacterial powder. Lights are 3000k LEDs from Invisible Sun with the "R-strip" retrofitted & the schedule is 20/4.
As far as ph is concerned, I've given up on it for the time being. Have just sent another ph pen back to amazon. They seem to last about 5
minutes with me I know my filtered water is high, around 7.5. With the biobizz nutes added ph drops low, around 4. After several hrs being oxygenated with a bubbler, ph was coming back up to 6.5ish. As I said though, I'm not testing it at the moment.
Question is, flush it or ride it out??

 

[Benjidubwise]

Actually, upon closer inspection, the second 19 dayer is exhibiting similar symptoms but to a far lesser degree...

 

[Death The Cultivator]

They look fine. The leaves look plump and lush. I'm seeing environmental problems. What's your temp and humidity?

 

[Benjidubwise]

They look fine. The leaves look plump and lush. I'm seeing environmental problems. What's your temp and humidity?

Thanks for stopping by @Damien50.
Environmental's fluctuatie a fair bit but never too far out of the comfort zone for too long. Temps are 22 - 32 (71f - 90f) but usually sits around 28 (82) during the day. RH is between 40 & 70 but usually sits between 50 & 60. Fans & filter on 24/7. Window & door to the room where the tent is are open as often as possible to allow for air circulation.
They don't look terrible by any stretch but I certainly noticed a clawing & yellowing of the tips after the last feed. Does't seem to be getting any worse so I guess I'll just ride it out for the next couple of days & skip the grow nutes on the next feed...

 

[Arthur]

Day 19 you should just be thinking of introducing nutrients in soil. A good soil shouldn't need additional nutrients until the bag is empty (figure 1 gallon per month of plant life) most start feeding somewhere after the second week.

The clawing I see could be nitrogen, she's a very deep green, but the way the leaf is heaved up in the middle, like the edges couldn't grow as fast as the centers...early sign of calcium deficiency. Both could be pH related.

 

[Arthur]

Hydroponic mediums, DWC or coco flush and reset would be the answer. In soil, you can't flush out the nutrients. Get a pH pen that'll work for you, plain pHd water, a little calmg... and ride it out.

From their website.

Additional fertilizer with an initial NPK ratio of 14-16-18 is also included, taking the EC level of the mix to between 1.2 and 1.5. For this reason, Bat-Special is best used when re-potting for the later vegetative or bloom stages, when plants can comfortably make full use of the additional feed. For very young plants, use a lighter mix such as Plant Magic Plus Soil Supreme, available here.

 

[Benjidubwise]

@Arthur Thanks for the input! That's a massive help. I grew several plants outdoors this season using the bat special. I didn't feed very much at all throughout the grow & they did fine (considering the poor weather here).
Before I started the tent running I read through the biobizz knowledge base on here & people seem to be feeding with the grow solution from week one so thought i'd give it a try.Will definitely water only next time though & see how they do. Will also order another ph pen

 

[Arthur]

Best way to think of those pens is a disposable part of the grow. Seems I go thru about 1 a year, but I haven't invested in the bluelabs pens yet.

 

[Benjidubwise]

@Arthur the 2 I've had calibrated once or twice then totally gave up. I keep trying different brands but they're all the same thing with a different logo. Can't really stump up the cash for a bluelabs at the moment... maybe I'll have to ask Santa.

 

[Death The Cultivator]

Thanks for stopping by @Damien50.
Environmental's fluctuatie a fair bit but never too far out of the comfort zone for too long. Temps are 22 - 32 (71f - 90f) but usually sits around 28 (82) during the day. RH is between 40 & 70 but usually sits between 50 & 60. Fans & filter on 24/7. Window & door to the room where the tent is are open as often as possible to allow for air circulation.
They don't look terrible by any stretch but I certainly noticed a clawing & yellowing of the tips after the last feed. Does't seem to be getting any worse so I guess I'll just ride it out for the next couple of days & skip the grow nutes on the next feed...

Your fluctuations are a bit much. 15f+ degree temp swings invite mold and pathogens. The swings in temp can affect nutrient and water uptake that can appear as a myriad of other problems. I like to keep numbers close, 77f-86f and ideally maintaining humidity within a 10% range, 40-50/60-70/etc. Plus nitrogen issues begin at the bottom of the plant, that upper clawing looks like environmental stress. I think your environment is more of an issue here but the I'm not seeing a real issue

Apera instruments makes some nice handheld meters. I have the 5 in 1 that measures EC/PH/TEMP and some other stuff but that's it. 7.5 pH water is actually quite nice, mine is 7.3 from the tap and if I remember correctly good drinking water is right around 7. The one below is inexpensive compared to $130 for the Apera

HAPHID Combo Meter Professional Water Quality Tester High Accuracy 4 in 1 PH/TDS/EC/Temp Digital Multi-Parameter Tester for Laboratory,Aquariums, Hydroponics Pool,Spa,Drinking Water and More Amazon product


The other thing is aerating your water will make your pH rise unless your nutrient line is stable. Everything I've used besides Mega Crop fluctuates hard and aeration isn't really needed outside of DWC. I run a 55 gallon res that isn't aerated and the ph takes weeks to drift.