Help please

Sorry this is so long, but I am trying to be thorough.
I am a newb, with a few ebb & flow grows under my belt. I moved at the end of last year, and went from having a 4'x4'x11' closet to having a full room to use..the room is 15'x17'x9'.
I had very few problems in my closet. I ran 3 crops to the end, and a 4th that got root rot from res temps and organic nutes, and went to making hash & butter.
Since I moved and set up my room, I have been plagued with troubles. DWC that went bad really fast and got scrapped and now my current issue.
Please, anyone with experience, HELP ME FIGURE OUT WHAT IS WRONG!!!.
I have 6 Nirvana Hindu Kush in a 3'x3' ebb & flow table. They are in 1' rockwool cubes in 6" nursery pots full of hydroton. The rockwool is 1" above the flood line.
The 10 gallon res is filled with aged tap w/ 35% H2O2 added @ 1.7ml/L. Res also has 4 air stones running 24/7 for aeration.
Res pH is ~5.8, with swings between 5.6 and 6.0 being as drastic a change as I have had in pH.
Res TDS is 148.
Res temp has not exceeded 63f. I use frozen water bottles to keep the temp down, if I have to.
Room temp is ~73 lights on and ~60 lights off.
Humidity is kept between 45 and 55%.
Table get flooded 3xdaily for 5 mins.
Light is a Sunmaster cool deluxe 600w MH in a Sunsoaker hood. It runs 18/6 and is 20" from tops of plants.
Three oscillating fans run 24/7, blowing on the plants all the time.
As I said the room is 14'x17'x9'. The table is open to the room on three sides, with the walled side being covered with mylar.
The seedlings were germinated in the rockwool cubes under two 42 watt CFL's at 24/7 lighting schedule.
When the roots were coming out of the cubes and the first real leaf set had formed (about 3 days after they sprouted), I put them into the pots and under the MH.
I top fed them plain pH 5.8 aged tap water for three days, then started their current flood schedule.
This was 11 days ago that they strtaed feeding from the bottom, 14 days since being put under the MH, and 17 days since sprouting.....19 from seed.
All 6 plants are still only 1 to 2" tall. They all have second leaf sets, but no sign of third. They just are not growing uwards.
I checked their roots and all 6 have at least 10 roots tendrils coming 2 to 3" out of the bottom of the cubes. These roots are thick and white.
I have tried misting the plants with pH 5.6 distilled water for the past three days, and it has not done any good. They are still not growing. They have not grown at all in 6 days, other than the exisiting leaves have gotten slightly wide.
The leaves have a definite light green cast, and not the rich green I am looking for.
The cotyledons are dead or dying, and the first leaf set are curling downwards.
By 11 days under HID lights, my experience is an average of 6" plants, and maybe even on their 5th node. These look like 3 day old sick seedlings with good roots. WTF???
ANYONE GOT ANY IDEA HOW TO MAKE MY PLANTS TAKE OFF!!!!
I am willing to listen.
PLEASE??????
ppm

It sounds like you are flooding your seedlings too much. If they are only a couple inches tall with only a couple of leaves, you should only feed them one maybe two times a day. The roots have to be able to breath.

How do the roots look?

Why are you adding ice to your res? If you are using H2o2 mold and allege shouldnt be an issue. Just curious

The roots look great. I will cut back to flooding one time a day, but I was afraid they would dry out, since hydroton doesn't hold water. Thanks for the advice.
I am adding ice, because I have had root rot, and I am paranoid. Trying to keep res temps under 70. Overkill???
Anyway....thanks for the quick reply. I don't want to lose these seedlings...which should be oplants....because I only have 4 seeds left!!! Will cut the flooding back for a couple days and see if there is improvement. Thanks again!!!

couple things to look into. 600 HPS with roughly 90,000 lumens at < 2 feet is extreme. The other is, from what u r describing and without any helpful pics, may be time to start a light feeding regimen, especially if the storage in the cotyledons has been used up.
temps seem on the low side, especially at night. res temp a little to cold for their age as well. 68-70 optimal for younger plants.
the good root development is a good sign. seems ur plant may be spending alot more energy on searching for water/food-i.e. the normal root development-and spending less energy on growing upwards. remember, you were top feeding them and now you are asking them to go and seek their own source of life.
u r correct on what u r doing-can not keep feeding from top and the cube must dry out to a degree between waterings. either there is too much evaporation from the rockwool cube from the 3 fans or not enough from low temps.
add a very light nute mixture to your res, increase the flood time by 5 minutes or decrease by 1 minute and add another feeding. skip the h202 for now. there are bene microbes that must exist in your res and they can not with the h202.
hydroguard was amazing until it came off the market. I am testing something new, basically about 10 strains of bene bacteria.
also, why arent they under the MH? they would fare better there than the hps.

They are under MH....I mistyped.....they are under 600w MH.
Your info is very good.
I wondered if the H2O2 may be too soon.
Do you think I could benefit by mocing the light further away???
I will let the res temp rise, but the room temp is what it is. If I plug in a space heater, I trip the breaker. It has been in the low 30's (farenheit) outside, but the temps are rising, so my room temps should get a little higher.
I wish I had pics, but I am at work right now.
I guess I will add some light nutes and raise the light.
I have never had plants stay seedlings this long. SO SCARED I WILL LOSE THEM.
This is exactly why I quit DWC, in the same room. After 2 weeks the seeds were still seedlings. This is frustrating.
I guess I will keep trying, however. Thanks for the help.

What is your ventilation like? Are you brining in outside are or supplementing with any kind of co2. I just moved into a bigger room too and that is my concern right now.

Dirtfree said:

What is your ventilation like? Are you brining in outside are or supplementing with any kind of co2. I just moved into a bigger room too and that is my concern right now.

Click to expand...

That is one of my major thoughts on what is going on. Air flow. That is the #1 difference from before. In my closet I had 2 exhaust and 1 intake fan exchanging all the air in the closet every 2 minutes.
In my room, I have no outside air coming in. 3 times a day I open the door of the room and run an attic fan to pullout the stale air, but I have no air exchange persay.
I have wondered if that is one of the problems, and have considered enclosing the grow table with a home made closet to be better able to control the air exchange.

It could be a conbination of alot of things. Is there any way to bring in fresh air?

not really....I could open a window, but they are boarded over.........I could cut a hole in the board, I suppose...but it would look weird from outside......maybe I can go through the floor to the crawlspace....hmmmmmmmmmmm

Thats what im going to do this weekend. Im going to cut a small hole in the floor. Something I can patch back when Im done. I thought about using the ac duct. Maybe that could work for you if ya have at least two ducts in that room.