Why does this happen.

This has plagued me for years and I've never been able to work out exactly why it happens.

Plants in coco smart pots, start off fine and then they will sit down and slow transpiration, so then you start to slow irrigation so they do not stay wet for too long, this goes on for a while, they get dark and just thicken up while growing slowly, all the signs in the world of over water with the wet-dry cycle being slow.

Now I take these plants outside and within a day they take off like rockets, which makes me think indoors the pot is not breathing, I have two rooms 10 x10, both identical ventilation 250ml in and 250ml out, with temp speed controller, the rooms stays at 27 day, 22 night. One room atm is powering, the other room is the above problem, next time it could be in the other room where they are sitting down, so then I think if its the rooms they would never be spot on which is not the case when they power they power.

So then I think Im over watering them early, maybe indoors has different air pressure in the pot and that's making my irrigations critical and if I step over that edge even just a little it sits them on their ass, just not sure what is going on but Id love to fix it for good.

Any ideas ?

The sun. Im guessing. Plants like it better.

I'm thinking its more about the airflow in the root zone, and maybe I'm just over watering them too early bogging them down, the good ones just go, but anything that's not booming goes bust, to watch them just instantly take off outside makes me think air, I'm wondering if indoors there is different air pressure inside the root zone from how it is in outside atmospheric pressure, I don't know but something is going on.

are your lights strong enough? if they aren't getting enough light, they won't respire very much, which is the main metabolic pump to draw nutrients up into the plant...
and just imo, coco isn't a good medium for any use except drain to waste hydro(which it excels at)...you do not want coco to dry out at all, or it will almost immediately start to damage roots

Sun is heating root area beyond indoor floor temps. Simple enough. Also better convection to dry out doors.

Pots sound too big for indoor climate.

Pots are 3 gal airports, plants about a foot high, I have plants in the other room same setup that are huge 4 fill the 10 x 10 room where I have to shimmy along a wall, lighting is a mix of 2 x 500 watt Led and 4 x 600 DE Cmh with a single vertical 600 hps hanging in the middle there is plenty of light.

The more I think about it I feel I just went too heavy on the watering and it sits some of them on their ass, then it cats and mouses with irrigations trying to get them firing again indoors, as soon they can really breathe away they go which doesn't seem to happen indoors that's the bit that baffles me, I have a mixing pump in the res but today I added a lot of extra aeration to the tank, I will also run some Peroxide to add more DO and see what happens.