Overwatering or Underwatering

[MrMuffinOCD]

Ok so i have an improvised grow with about 175 wats of CFL lights with a mixture of blue and yellow lights. I have 5 plants total, 3 of them are very young (6 days) and the others are a bit older (17/18 days). The younger ones are doing fine but the older ones are showing some signs that i am having trouble understanding if they are related to under or overwatering.




They were transplanted around 6 days ago and after the transplant i watered them twice, once for the transplant and another time 4 days after because they looked dry. One of them is looking healthier with only little signs like the tips of the leaves curling up and a slight droopiness. The other one has a more severe drooping and shows the same curling tips. At 1st we had no ph tester and because we knew that the tap water was around 7,5 we were adding 3/4 drops of cider vinegar wich now we know it dropped the ph to 6/6,5. I am sort of convinced it may be underwatering because the leaves look really thin and papery but my girlfriend thinks its overwatering because the photos we see online look similar to our symptoms. both opinions seem valid enough to be true so i am making this post to try and find an actual answer and maybe a solution.




Extra Information

We are using pre-fertilized soil with a ph of 6,5 with perlite (about a 1 part perlite to 2 parts soil)

The soils is not muddy and pretty loose

We have a fan that is always on (not too strong but it does the job)

The place has a high percentage of humidity (we estimate around 60/70%)

We still haven't used any nutrients because they seems too young for it and the soil is pre-fertilized as stated above

We have them on a 20/4 light schedule


PS: we send photos in the link below the first 6 photos are of the extra droopy one and the last 3 are from the one that is healthier but still with some signs like curly tips

https://imgur.com/a/1RBVxsC

Edit: one the photos of the healthier one is mixed with the photos from the other. but i think its pretty obvious wich one is wich

[azorahai]

With the amount of perlite in the mix, I wouldn't worry around overwatering, as it provides good drainage and aeration. Also, because the humidity is high, I would keep the fan blowing in such a way as to make the leaves sway slightly (don't point it directly at the plants, nor completely away from them) so they'll transpire more quickly and pull enough water/nutrients from the soil.

I would venture a guess and say it's underwatered. Either way, what I recommend is next time you water them (until some of the water runs off the bottom of the pot, the idea is to thoroughly moisten it), pick them up to have a feel for how heavy they get, and next time you think they need watering pick them up again. If they are still kind of heavy, they can do without being watered. If they are light, then proceed with watering. Eventually, you'll know when they are past the watering time (they'll droop and the pot will be super light), and plan around that, so you're not watering in excess nor leaving them dry.

Edit: oh, and I would also poke a lot of holes in these pots, and/or eventually transplant them into fabric pots or airpots, to help with root aeration

[MrMuffinOCD]

i filled a pot with just soil and weighted it and it came up to 1222g and the ones with the plants that i watered 3/4 days ago and they came up to 1750g and 1830g on the other so there is still a lot of moisture inside. so now i think im gonna wait a couple of days before watering them and then ill do the run off method and all the things i have seen about how to water them properly.