She’s not a seedling yet. She is a sprout! Move the light back up if you haven’t already! Welcome to ILGM I’m a soil grower here in Massachusetts USA!
PH is the King/ Queen!
Temps are second in DWC (from what I’ve read)
Best wishes on your grow! @Dopehat
Thanks for the tag @Countryboyjvd1971
DWC is awesome, you’ll love it @Dopehat! Happy to see you got a sprout going! And that Mars II should be perfect for you to grow some amazing bud with!
@bob31 is right on point, pH is so extremely important when growing in DWC. You’ll want to get a good pH meter if you don’t have one already. Water temps are important as well, but they’re harder to control than pH.
We’ll get you there as you keep chugging along, we got your back!
Looks fine for now, if she’s growing and not stretching crazily it’s at the right height of say, move closer in veg til you see negative effects to push her limits or play it safe, makes me want a HID light tbh as i found it a pain to find the perfect spot
Thanks again everyone!! You’re all making this so much more manageable!
I’ve left my light up at 30" for now and I’ll be getting a PH tester kit today.
It’s amazing watching her grow so fast!! 
I’m doing my first grow right now in soil and don’t know much about hydro. But anxious to see how it comes along!
I’ll be following @Dopehat woohoo look at them go lol
I’m a soil grower my self but if I didn’t mention it already @Donaldj is a solid dude to contact if you need help with hydro and @Hogmaster I believe can square you away as well
I know enough about Hydro to get me in trouble I’m good indoor soil outdoor soil as well and now promix is my favorite buddy along with flower power 
And just so you know the cubes ph on them are A neutral 7 pH even if you ph at 6 the cubes Will still have pH of 7 but you are on the road to success
You know me I’m good about getting in trouble LOL just kidding
Ok so i definitely see the first set of true leaves on her now! According to the instructions that my hydro guy gave me, I believe I should be opening the propegation vents to 75-80% humidity (see picture attached of his instructions, 3rd dot point from the bottom!).
So from my understanding I should open the propegation vents to 75-80% humidity (vents are currently closed, 100% humidity) and if she stands strong (maybe for a couple of days?) then it’d be time to transplant her into my pot? Also, does she look like she’s stretching? The LED light is still at 33".
Thoughts anyone? 
So she’s been transplanted into her DWC system a bit over a week ago on July 15.
Today I finally see a root coming out from the bottom of the mesh bucket, it looks to be her tap root from my limited understanding.
I think she’s looking pretty happy at the moment (?). She’s still got yellowing on her bottom leaves from a few weeks ago that’s stayed the same but nothing further has happened with that so I’m hoping it’s all ok (you can’t see the yellow leaves in this pic attached). I think that may have been from incorrectly PH’d rockwool or my local Hydro store suggested she may have been hungry at the time.
@bob31 Do you think I should have the fan on in the tent to create movement in the air? Is that important?
it wouldn’t hurt to run your fan and your ppm is about right though keep an eye on your res temp you won’t want it to get much higher or can cause potential grief
Thanks @Donaldj I know my res is as high as I’d want it to be. I actually put a water heater for an aquarium in the res to keep the temp at 20c / 70f (that’s the lowest temp it’ll set to) but now wondering what temps might be if I turn it off all together. I just didn’t want water to be too cold (although maybe room temp will be fine). I might turn it off for a day and keep checking temps.
So I just checked temps and the water reads 26C / 78.8F so way too high. I turned off the water heater I had set to 20c and I’ll come back in a couple of hours to see if that makes any difference at all - I’d always been concerned with water being too cold, particularly overnight but I think my concern should have actually been with it being too hot! Seeing as I just had the one LED light which doesn’t put off much heat I thought it wouldn’t get too warm in there, guess I was wrong!
Anyway, just wanted to update my grow journal with what’s been happening. I’m about to go and read about the best/cheapest way to deal with this, so far I’ve read advice to freeze Coke bottles and keep changing them over, I’m hoping if I can fix it quickly that everything should be ok.
On another note, there’s now about 5 visible roots that have reached the reservoir. I think she’s looking happy currently and I’m loving watching her grow (despite the anxiety!)
So I’ve managed to get the water temps down since taking out the water heater but not low enough. They’ve been around 22 - 23 C or around 71.6 F. I only need them down a degree or so!
I’ve looked at water coolers but they’re just too expensive. What does everyone think about putting a frozen bottle in there? It’d be so much maintenance to keep changing once or twice a day but may be my only option right now! Won’t the roots touching a frozen bottle shock them? @Donaldj @bob31
…And here’s a pic of her today. She’s really growing!!
