FEW PROBLEMS IN GROW ROOM

Got a few problems in my grow room if anyone has any idea why they’re happening and how to go around sorting them out would be much appreciated. This is my third grow so still learning.

1. First problem is I have noticed today one of the plants soil is still wet, I watered them 4 days ago and the rest are dry could do with another watering but this one is like none of the water has been absorbed also the plant is much smaller then the rest and the leaves have went a strange yellow colours. I don’t know if this is something to do with the roots? The plant is auto northern lights grown in soil under led lights.

2. The second thing I've noticed today is one of them is drooping and the leaves are pale green compared to the rest. They have all been watered the same and had the same nutrients so don’t know why it’s happened to just this one? this one is a critical mass auto grown in soil.

3. Another one of the critical mass autos leaves are drooping but just on one side the rest of the plant seems fine apart from the one side, don’t have any idea why this would be happening the temps are ok and they are being watered at the right times, it’s only on this plant that it’s happening no others.

all the plants are in late stage flower grown under 2000w mars hydro led lights in biobizz light mix soil and watered with biobizz bloom and top max nutes as well as terpene booster.

I was thinking about flushing the two critical mass with ph’d water for a few waters to see if that clears the problem and just leaving the northern light to dry out and see if it sorts it’s self out?
If anyone can shed any light on what’s happening and how to fix them would be much appreciated, thanks.

Most of the issues you are having can be attributed to overwatering but your plants could also just be in smaller containers than they need to be. Drainage through the bottom could be at the heart of the problem; be sure there’s big holes in the bottom of those containers. The containers you use look a little shallow to me but maybe vertical space is limited. These are related because for fast growing roots that suddenly need more room it quickly becomes harder for the soil to regulate moisture. Plants in small pots typically need to be overwatered to keep from drooping. Droop is usually related to too little or too much moisture so potting up, improving drainage, and/or simply changing your watering strategy might be easy fixes. Keeping the soil moist but never saturated can be harder than it sounds.
It looks like the plant that is turning yellow/red is maturing; don’t worry so much if it is taking less water. Plants in late stages need less than plants still developing. It’s natural for the fans to turn colors near the end especially if the plant is feeding organically from the soil and temps dip at night.
The plants that look to be in early to mid bloom phase will need a boost. Here’s where your soluble npk helps get them over the finish line or you could also do a top dress with something high in N and P (kelp,fish bone meal, ewc) but nutes go to work right away. I would give them Neptune’s Harvest or equivalent liquid fish emulsion but that’s just me. Maybe you can just pump up the dosage of biobizz.
Don’t flush, just water as needed. I would try filling up the containers to the top with fresh mix first after making sure the bottom of the containers are not saturated or even anaerobic (smells like a pond). Add worm castings/compost if you have some. If drainage is good through the bottom then try watering more or less often but with less water. Try giving a light watering more often instead of drenching then every few days. Feed them just a little more than you used to.

Thank you for the reply, great help. I will try doing what you suggested, hopefully this will sort them out.

Good advice from Richard. First thing I thought was poor drainage, make sure the pots are nice and light before adding more water / feed. For drooping leaves on one side, make sure you don't have a fan blasting that side of the plant. The pots look a little shallow to me too, need plenty of room for the roots.