Strangest story, please advise...

I brought very healthy & happy 2-3 month old plants and some newly rooted clones to a brand new built location.
The Veg room had 4 big t5 lamps covering two 8x4 tables.
I soaked the 4inch cubes in RO water without CalMag planted the clones.
Then I watered the big plants with a different formula, because mine was not available that day.
Two days later both the clones and the big guys start to turn yellow...
i can understand why the clones might have stressed, calcium deficite... But why the healthy plants?
Then I checked the fosset water, it's 500 ppm
Could the big plants stress from hard water ?

Anyway some one else was trying to grow there, same things happened... But he only tried using RO water, and I know thats not a very good idea...

Out of all the craziness, is there something that can be sprayed in the room that makes plant stress/die? Because some haters had access to the premises, and we don't know what to think...

n1k1tozzz said:

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I soaked the 4inch cubes in RO water without CalMag planted the clones.
Then I watered the big plants with a different formula, because mine was not available that day.
Two days later both the clones and the big guys start to turn yellow...
i can understand why the clones might have stressed, calcium deficite... But why the healthy plants?

Click to expand...

Ok first were they cuttings or clones? Cuttings do not have roots, clones do. Until a plant roots itself it survives by foliar feeding and cannibilizing itself. The going yellow is most likely a sign of needing nitrogen. But that is only a guess because no good images only your explanation.

I am also a newbie so please take this with a very large grain of salt. By the time my first clones were fully rooted they looked pretty yellow and ratty (I didn't foliar feed).

n1k1tozzz said:

Then I checked the fosset water, it's 500 ppm
Could the big plants stress from hard water ?

Click to expand...

No an overabundance of Cal/Mag won't hurt them. But it won't feed them either. It can also in huge amounts lock out other nutrients. Hence why RO water is a good base as you are starting from virtually zero so you know what nutrients and supplements are available to your plants and do not have to guess.

n1k1tozzz said:

Anyway some one else was trying to grow there, same things happened... But he only tried using RO water, and I know thats not a very good idea...

Click to expand...

If that is the full story they died from lack of actual plant food (NPK) Nitrogen, Phosphorous, Potassium. RO water alone will not sustain a plant. Seedlings contain all the food they need to begin life so they can exist with fairly deficient water. Further Cal/Mag is only a supplement and not a plant 'food'.

It's sort of like us and our vitamins. If you only drink water and take vitamins you will die from starvation. If you only eat food but do not get a balanced diet and do not take supplements then you won't die but you will be sickly. It's the same for plants.

NPK is critical the rest enhances health. But again I am a very new newbie so I could be wrong.

n1k1tozzz said:

Out of all the craziness, is there something that can be sprayed in the room that makes plant stress/die? Because some haters had access to the premises, and we don't know what to think...

Click to expand...

Yes of course but it sounds like there were enough mistakes they didn't need to actively kill them. I strongly recommend you find secure grow quarters that are only your own. It's much safer for you in the final analysis. If these guys really hated you they could spray something on the flowers that would make you sick. Not simply kill your plants so for your own peace of mind a secure grow space of your own is essential.

I know this is frustrating. I am a newbie and sorting good advice is tough. I strongly recommend getting Ed Rosenthal's book and/or a book by Jorge Cervantes. So you have a single simple resource that you can refer back to for confirmation on advice you maybe given.