100w LED is good for about 3 or 4 sq ft, 300w for 16 sq ft is only 18.75w sq ft, not enough in my mind, 550w would be more like it. (IMO)
My 4X4 flower tent has 750w HPS and the 4X9 veg tent is running 1,600w LED
So IMO you'll need more light.
Good luck
From Royal Queen Seeds
How Much...
My 4X9 tent is hung with 1,600w LED
So your 8X8 could run at 3,000 watts. 2,250 would be my minimum.
I used tap water when I did DWC, co can't help there.
Just my opinion....I prefer to have a healthy unstressed plant to go into flower, that way it' can put it's energy into flowering rather than having to divert some of that energy for healing. I've flowered enough stressed plants in my time.
But if you're in any kind of hurry, go for it.
agree with Boatguy -
Looks like you're using about 16 sq ft of grow space right now @35w/sq ft, you should be running (IMO) at least 550w
I run my 4x4 flower tent at 750w
have fun
Your spawn, or retail?
I'm a noob, but proper hydration of the spawn is a must, and 6 days isn't long, if it cool it takes longer too.
Be concerned in another 2 weeks
Have fun
A couple of these would do for 9sq ft
https://www.amazon.ca/CHVEGLUZ-Samsung-MeanWell-Spectrum-Upgraded/dp/B08JSND8SZ/ref=sr_1_7?crid=1CBI1R9WKLA1E&keywords=grow%2Blight%2Bmeanwell&qid=1672868235&sprefix=grow%2Blight%2Bmeanwell%2Caps%2C103&sr=8-7&th=1
I really don't know how 4 days 12/12 will affect your plants, but if they're in flower it will take several weeks for them to switch fully back to veg.
Good luck