once again - trouble for seedlings in coco - strange shit

Growing in coco-perlite 50-50, 400w HPS (about 2' away currently), 26.5 celius, got fresh air blowing right on them.

I have two batches going on now. For the first batch I took coco straight out of the bag, and only added tap water, about 0.7 EC, pH 7.8. Dutchmen's Royal Orange, 10 of them - sprouted last wednesday pretty much. Currently only 8 left. After initial signs of problems, I flushed them well with RO water to runoff of 100, then recharged them with HESI Coco nutes, 0.6 EC/pH 5.8-6.0.

And the second batch, I again took coco right out of the bag, again with the tap water, but this time just a bit of it. Serious Seed's Chronic, sprouted on Saturday, they are looking more healthy though (with some minor problems), just a bit of stretching. When they dried I gave them another small watering with HESI coco 0.6 EC.

So the Royals are giving me trouble. Their cotyledons are good, but the first set of bladed leaves in most of them is quite twisted! Either fully twisted down or straight but facing aside in 90 deg from one another rather than 180. This began before flushing but seems to have gotten worse on some of them since them, and two died, one before and one after the flush.



Some of them look better - but have some strange residue or discoloration one the blade leaves, not sure what it is. Looks a bit like scale, as in calmag buildup:



also on the first batch I sprouted one of the chronics - It is the biggest seedling I have right now. It had a bit of a rough spot of what looked like a burn on the first set, but then it went away, after the first flush, and it moved from looking a bit light color after the flush, to looking a bit better after the stronger feeding:



and the other Chronics from the second batch are younger but seem to be in strong shape, although a bit stretching.



On my last grow, I also had problems with the seedlings, also in coco. I somehow figured it out with flushing and slowly recharging them, maybe I should just be slower about it, more gradual?

https://www.rollitup.org/hydroponics-aeroponics/415445-help-coco-not-looking-good.html - this is the thread from the last grow.

I appreciate any help. but please don't tell me all about how you grow. I need advice on what to do now, not knowledge on how good your last grow in soil outdoors was. I too can think of some stuff I did wrong, but please let's look into the future here.

I would not give your seedlings any nutrients. They look very unpleased by the feedings

yeah but they were unhappy before the feeding as well. also, if you check out the previous grow, you'll see that what helped them eventually was feeding them. coco is not like soil you see.

I think this is either pH, or a genetic thing.

The only nutrient burn I can see there is on the biggest plant, and that is from when it was in unph-ed tap water.

then again that plant didn't have growth stunt, and is so far the best of them.

Been using coco myself for a few years now. I use 100% coco to grow in. Ph should always be at 5.8. The twisting of leaves are over feeding with the nutes. It will dry out the leaves and eventually die as the nute burn takes all moisture out of the leaves. If you can get your humidity up above 65% to help the leaves retain as much moisture as possible. Depending on how much you over nute them will take longer to recover. The leaves already on the plant might not fully recover but new growth should be ok

jafooli, what ppm/EC do you give your seedlings in coco?

In coco i use plain tap water Ph to 5.8. Where Im from i have to let water settle in my resivour for 24 hours before i feed. Going by your pics you will still have some nute in your coco so just flush with Ph water thred times the size of your pot. Good thing about coco very hard to over water. One thing up against soil

Once the plant gets to second set of leaves i start adding nutes ec running at 0.2. I give them a week to feed every day for ten mins on pump on a recirculating resivour. By this time i can see the colour of the leaves and i just up feed as and when the plants show they want more food. Leaves are a lighter shade me green

now i found that the medium pH is too high - 6.6. no matter how much low ph solution i put through it, it won't go do.