Any idea why the leaves are curling up around the edges and are very dark green and textured on this plant?
What are you feeding them?
General hydroponics, In ml per gallon,
Silicone 1ml (allowed to dissolve for 1 hour)
Cal mag 4ml
Micro 2ml
Grow 2.5ml
Bloom 1ml
Diamond nectar 5ml
Pouring 1 litre through each plant, feeding once per day currently but have been told this may be not enough.
One plant seems to be showing potassium deficiency too in my limited knowledge, pics below
Do you ever pick up the pot or check the moisture before watering? Could need another feeding, and certainly looks hungry. I use 100% perlite and keep my pot size to watering twice a day or every 6 hours be it 12 hours for flower or 18 hours of grow. I’ve experimented with allot of medias and found the most success using agricultural perlite.
pH is often a cause of leaf canoeing. You may have a salt buildup? 6.5 out suggests there may be.
Are those wet leaves in the first pic, or is it a dark, waxy looking color instead?
Cal mag.
OP is in coco so daily watering is expected. No need to water to runoff yet as plant is small. What is your schedule of watering versus feeding? What kind of water are you using? If tap what is the TDS?
Hi its seems no matter what I do I always seem to get the same ph out it never changes, and they are waxy looking leaves
I tend to fee them once a day now when the top of the coco is just about damp but not wet if that makes sense
Too much or too little calmag?
I wasn’t aware I should feed them and water them separately, if that’s the case I can start that ASAP, I can use filtered tap water with a ppm that never seems to exceed 280 would that be OK?maybe too much water/neuts? as I get a decent runoff using 1l per 19l pot
This is just high enough I’d suggest you look for a better water source. An inexpensive R/O unit like the R/O Buddie will work well. It begs the question: are you accounting for that TDS in your nutrient schedule? This is why people in media like R/O as they control the entire nutrient load. Remember that it’s all additive and has to be counted as part of the total TDS.
I give cal mag at waterings as it drives the TDS up. Normally you would do a feed/water/feed/water.
True for soil as well? I usually just try to maintain a target PPM and end up feeding on every watering. I’m beginning to question this as things like silica and even pH Up add quite a bit of PPM on their own.
@Myfriendis410 your a legend thanks. I take tds readings including the base water which gives me 700tds on average. I will certainly look into an RO setup (more plumbing 
)
So I should cal/mag with feed and with watering and cycle them feed/water, I will give that a go
My PH went nuts with cal mag too when mixed so I just broke it out from the rest of the feeding regimen. I also don’t run cal mag at every watering.
Did you buffer your coco with a cal mag soak before planting? Some coco needs to be washed and buffered before use. But that looks like slight calcium def to me.
I usually only run cal/mag during flowering. OP: this won’t necessarily apply to you as you are in coco.
I do my cal mag separately from nutrients in general.
This is what you are supposed to do. The problem though is it’s almost half your nutrient load is in your tap water, which you don’t really have control over. Starting out with near zero allows you to give it exactly what you want.
Then if you mess up it’s on you haha.
So best pull calmag from feeds and just add it to watering schedule.
Its pre buffered coco but I still pierced holes in the bottom of the bag and rinsed ith through with a hose then mixed it up in a huge bucket of water and calmag and let it sit for 24 hours, I then ran ph 5.8 water through it before use
Sounds like you are on top of it. Likely the plant will sort itself out. I would update my water supply whenever possible.
You might also double check your calibration on PH meter to make sure you aren’t throwing them a feeding out of range. I keep some ‘7.0 Standard Reference Solution’ handy that I can dip my probe in for a quick reference.
I just bought a new mwtwer it’s not scientific grade but it’s a vitalink one was £40 so I guess low to mid range I calibrated it the day I got it (2 weeks ago) and I leave a little ph7 calibration fluid in the cap too as advise by yourself I think.
I’ll change over to what you said and feed once, water once and see if that helps me out. Thanks again for your advice your always so helpful 
R/O system ordered looks easy install too
I just put one in. Love it!
