SOIL Problems migrating from HPS to LED

[acsanches]

Hi everyone,

It's been a long time I am thinking about posting it here to get some opinions, so sit tight because I think it will be a long post.
I have read a lot of the posts from growweedeasy website, but somehow I think that I lack more examples of LED.

So last summer I grew two Auto Tangerine Dream in a 40x40x100 tent with a 600w HPS light that a borrowed from a friend, also using regular soil with no additional nutrients I supplemented with Canna Grow and Bloom as per the manufacturers schedule. It was my first experience and it worked pretty well, I got pretty good yields from them (around 70g total) for a starter.

This winter I decided to start my own setup, and I think things are not going well because my plants seem small comparing to photos/weeks of the previous.

So first of all here is my current setup.
Tent: 60x60x140cm Secret Jardin series Hydro Shoot
Light: VIPARSPECTRA Reflector-Series 450W LED
Flower pots: small ones (probably 500ml) for the seedlings and 11l square ones for when they are more grown up.
Carbon filter: ECO fi125mm 160-240m3 / h
Growing medium: Perlite EP-AGRO 3-6mm; Plagron GROW MIX 50L-flowers earth CANNA TERRA (Pre-fertilized for 3 weeks, NPK 12-14-24)
Nutrients: Advanced Nutrients Grow Micro Bloom (which I haven't used yet as my earth is pre-fertilized), B-52 and Voodoo Juice as well from the same manufacturer (which is the only thing I have added so far).
Water: I'm using filtered tap water and making sure the PH is between 6.5 and 7 with the aid of PH down/up and a digital PH meter (calibrated and cross checked with a friends PH meter). (here's where I think I made some mistaked which I will explain later).
Seeds (all autos): AK47 (hemp brothers), Thunder Bloody Mary (samsara seeds), Mazar (dutch passion, freebie), Royal Haze (royal queen seeds, freebie).
Light cycle: 20/4.
Temperature is between 25 and 30 degrees (it's being hard to keep it steady)

I hope I have provided some good amount of data to help (there are also some photos attached)

So here is my main concern and some other facts.
Concern: my plants are growing slow, and as you can see they don't look very healthy).
Facts:
- So my room is closed most of the times because it is winter, so I don't have the chance to leave all my windows opened gathering fresh air as I did back on summer. (therefore I have prepared that CO2 solution you can see in the pictures which I change each 10 days, some times I also try to leave the window of the tent opened to try and get some "new" air inside).
- My lights are all the way to the top (85cm from the Thunder Bloody Mary) as I was afraid it would burn the plants. (I still have no idea if it's right or wrong).
- In the beginning I think I gave too much water for the Thunder Bloody Mary because I was used to do so on summer, but I realized that the water is not going away as fast as it was so I am giving not so much now, I was giving 500ml now down to 200ml (per day) and the other smaller ones just 30ml (per day).
- The dates you can see on the photos are the day and the month (of 2018) that the seedlings sprouted, so add +- 3 days before that date for the germination.

Should I keep those plants (almost 3 weeks for Thunder and 2 weeks for Mazar, and they look very small, look at my 2 weeks Tangerine Dream in the photo attached)?
Am I doing something wrong?
Is there any difference in the process of growing with HPS and LED that I should be aware of?

[Waltermelon]

I'm a little concerned with your watering schedule. You said you're watering once a day?
Mazar from my experience is a slower growing strain and takes a bit longer to veg, but the crystallization you get at the end of flowering is AMAZING.
You can also move the light quite a bit closer. Viparspectra says your ppfd at 18" (not sure of the conversation to metrics because we use a backwards system of measure in the us...) Is around 700. You having the lights much further than that away diminishes the ppfd very quickly. Study's have shown for veg marijuana grows the quickest at 800-1500ppfd per meter squared without co2 supplementation. You can go up to 2000ppfd with co2. First start with a proper watering schedule and do some research on your led panel to try to get your light density up where it should be.

[Waltermelon]

You can start to do a little research by googling "university of Mississippi ppfd marijuana". That will bring up a huge amount of info that will make your head hurt to begin with. But as you start to slowly process it, it will make a lot more sense.

[acsanches]

Hi Waltermelon, I am watering a bit every day, around 100ml each of the bigger plants (I was adding 1L before and I had over watering problems) on the photo and 30ml on the smaller, I am for sure having problems to adapt my watering schedule, I think I might need to increase it slowly and see what works best. Regarding the lights I already changed to what is recommended by the manufacturer so it should do the job.
Nice one about Mississipi UN, I did not know it, will read more.

[Waltermelon]

Not sure why they would recommend you attempt to grow a plant that needs 700-1000 ppfd with a light that puts out 700ppfd (on the low end of the spectrum at 18") up any higher, especially at 2.5'. your ppfd numbers are probably around 350-400 at that height. That's way too low and if a manufacturer is telling you to grow a plant that needs 700-1000 ppfd, with 350-400 I would question their knowledge base. I use a v600 viparspectra in a 3x3 tent at 12". That's not enough and added another 600w bloomspect led.