2nd grow going in coco, few questions

Hi, first post here, kinda paranoid to ask questions openly, but here is goes:

How are my plants looking? the tips on my leafs are tiny bit burned I think, but it could be a deficiency also, I'm not sure. I watched that MRgrowit video with Mark Boutwell, great info! Also the smaller plant is lighter green, I think I was feeding too frequently at the start and it got stunted a bit. now I'm doing it each other day, to good runoff each time. I put the seeds in the final pot exactly a month ago, and they sprouted 27 days ago.

I got 2 autos of the same strain, Dutch Passion Auto Cinderella Jack.

This is whats going on right now:

DIY grow box inside a wardrobe, 95cm x 55cm x 165cm.

Meiju 240W 3500k full spectrum light (no red/far red diodes) I run it currently at about 100W

I checked my PAR with a android app so not so accurate, but its reading right now 500-600 PAR at the canopy. Chinese light tho but I was happy with my yield on the first grow, the quality suffered from letting the pots get 2 times completely dry (coco) and noob mistakes, I dont think it was because of the light.

Computer fan for air movement, and a exhaust fan and carbon filter.

Temps are around 26 Celcius with lights on, 20C off.

Humidity is most of the time at 40%, cant get it higher besides when its moister outside. at start my humidity was too low, like 30%. Last grow I had a humidifier in a tent but it was a PITA to fill it like 2x a day, and then it broke + wont fit in this small grow space I got going now.

18/6 light cycle

17L Fabric pots filled with Canna Coco + about 13% perlite, top of soil just coco.

For nutes only Canna coco A + B, first 2 weeks I used also 1/8 strenght canna rhizotonic, then i ran out. (had small amount left from last grow)

I feed them now basically at 1/4 strenght, 10ml a+ b in 10 liters of tap water. my tap water is about 530EC and with the nutes it sits at about 1000EC. I ph to 6.0 My ph pen is crap so I double check with those PH drops where u check the resulting color, hence why I aim at 6.0ph as the drops show only 5.5, 6.0, 6.5 ph ranges :( I also bought a air bubler stone so now my last 2 feeds have been with water that I let bubble for a day.

Doing some LST and leaf tucking, didn't feel yet good about defoliating, should I do some on the bigger plant?

I'm mainly concerned That the smaller plant has some deficiency / toxicity after going trough that awesome Powerpoint presentation Mark did :) to me it looks either like Sulfur Def or toxicity.

Also I got 1 huge dilema/problem. There are none local shops that sell any nutrients besides general gardening stuff. its 1 whole weekend trip to go to the closest "hydro" shop and expensive ferry tickets. I cant order anything online its too sus for me. Basically I gotta work with what I got for the most part of this grow.

All I have is huge amounts of Canna coco A+B, a bottle of canna PK booster that I burned my plants with last grow, and dry epsom salt.

Woah that was too much text! Waiting for some inputs. :)

ps: Loving this grow discussion this forum and dudes on youtube assosiated with mr.growit has going on ❤️