Yellowing leaves problem... Some advice please?

Hello everyone

I was wondering if someone could assist me a bit... My plants look
like in the pictures attached.

Some information:
The soil I am using is BioBizz all mix. I have fertilized 3-4 times with
Biobizz BioGrow with 1ml/lit (gave each pot around 300ml each time).
Started fertilizing at the end of Week 2 and on the ones that were
more than 15cm tall.
The pots I am using are 18litres and the plants were potted in them
directly (not good that I didn't use smaller pots at the beggining I know..).
Their age is 27 days and were planted from seed. The temp in the
growroom is 27 C at lights on and 24 C with lights off. I always leave the
water 24h on a bucket before watering with it for the Chlorine to evaporate.
The plants began to show yellow leaves at the bottom and they were looking
droopy too. Some of them even have a 2 colored leave (lighter green on the left
side and darker on the right). Also they are not growing taller for about a week
now. Its as if they are all stable.

What is going on? Am I overfertilizing? Shouldn't the leaves have burn marks
if so? Also 1ml/lt is the amount of nutrients that are suggested on the Biobizz
chart. Is it possible that this is way off?

Unfortunately I don't have a PH meter or EC meter yet and I can't tell
if something is wrong there...

Please give me some advice as I am starting to panic!

Looks hungry man.

The little ones there are Nitrogen deficient along with Magnesium .. I think you ll find that a PPM meter will be to your aide and it will allow you to adjust the strength of your nutrients , those plants are going to be feeders and youll want to give them all they need ..

I reccomend running them at least 800ppm to begin and go from there , this way you can really see how they respond and record each feed and ppm , didnt see much about soil here but Peat mixtures will give many growers a headache due to ph and that would be my next concern ..

You might be approaching a low soil ph and that will also stop them from feeding , try for 6.2-6.8 and water with a higher Ph if the soils is low . Most times not Soil ph is behind this issue above and it helps to maintain a strong buffer in the soil by adding your own and not relying on the manufacturer .. They often add only enough lime to hit there mark and with time and aging you get sour soil that only sours more when feed .......PotSnob

I'm completely new to all of this, but 2 out of my 3 plants had yellowing of the original seedling leaves. I bought a PH tester, made my water/nutes were slightly acidic(that was 2 days ago). Today they're super perky!

I agree with PotSnob. I'm using old soil, bad nutes, bad setup, bad lights... but just changing the PH levels has given me dramatic improvement.

Thanks for the reply guys... Isn't it strange for the plants to be starving that much
when the soil is new and from a company that is supposed to provide enough
nutes in it for at least the couple of first weeks? And also I did give them nutes but
at the rate biobizz suggests. A lot of people say that at least for soil use less than
the company suggests especially when the plants are young. After all that what I am
getting is nutes deficiency? Thats strange...
I think a ph problem is more probable than nutes starvation in my case but yet again
I d like a second opinion from other growers.

I would say a ph issue is your problems either from just that type of soil or the soil is wet most of the time, if your ph is out of range your girls cannot use the nutes and it will show and adding more will not fix the problem but make it worse I would add some lime to your soil and water it in it will help keep your ph buffered and just water your ladies with 6.5 water I hope this helps, but just IMO I would say a ph issue.

Coming back with an update since the ph meter arrived. The ph of the water coming of the faucet
is 7.8 - 7.9. After leaving the water 24h for the chlorine to evaporate it reaches the ph of 8.2
I dropped 1ml of ph down (essentials phosphoric acid 81%) in the water (10L) and the ph went to 6.3.
I poured that water in a pot and measured the water that run out the bottom. Its ph was 7.1 - 7.2.

That means my ph on the soil is quite high right? Could that be the issue of the problem? Also my grow
tent is self made using some white reflective plastic and Styrofoam for the roof. After some reading
I found out about the offgassing that can occur from PVC materials and I am thinking if that also
affects my plants...

At any case I got a Jardin 120DRII coming over pretty soon so this could remove a potential hazard
from the equation.

From the look of the leaves(twisting) i can tell your PH is too high and in soil it should be 6.5 but 6.0-7.0 is doable but i recommend a range of 6.3-6.8

I had this same problem a couple weeks ago. honestly i am unsure what the problem was but I fixed it

I ran a ton of 6.5 phd water through my soil ( about 5 times as much dirt as i had) I waited about 4 days tell they were ready to water ( I kept the room warmer in hopes the dirt would dry faster) I fed with 1 tsp per gallon growbig a bit of epson and a touch of calmg and a few days later the the growth was green and nice.

yup yup. Mine are still in their first month, the first and secondary leaves are starting to yellow. figure its not a big deal since all others and new growth is ok. Gave a little nutes and water at correct PH, we'll see in a couple days, if it gets worse I'll get a soil reader I suppose.

hi guys i have exactly the same problem :/ im waiting for the results of my watering now- i put some lemon in the water to lower the ph. i was very suprised as well as im using all mix soil from biobizz and they say its enough to keep young plants fed for about 3 first weeks...and since 2nd week seedlings started to show yellow leafs any progress with your plants digitron? i think if there is no improvement im gonna do it the way [FONT=Arial, Helvetica, sans-serif]socalledchad did .......[/FONT]

I would say try it out. It really cant hurt. All your leaves may not turn back to normal but your new growth will come in green and if that doesnt happen you know you are lacking something. Also I was looking into making a drip type watering system like it looks like you have my Idea was to maybe run it for a couple hours everytime they needed water and I wouldnt have to to the bucket thing and hand water all the time but many people suggested i may get an uneven water and maybe the ferts would be alot less ...or more at one drip point or another. I dont really know if thats true or not

I just want to input because I was so proud that I got mine looking perfect and Im fairly new lol. a good flush followed with a good feed.

also I will add.....the plants that had the yellowing problem came to me about 3 inches tall in same size pots as yours and the yellowing came about the same time as yours. The person I got them from did tell me it was reused dirt he had in all the pots and that he had let the dirt sit outside in a pile for like a month in the rain, and I am sure that made the PH levels sway one way or another which Is what I am thinking was the real problem in the end.

How are they doing?

Running ph'd water through your soil is not going to change yor soils ph. Waste of time. It's a band aid at best. The medium is going to adjust itself in a few hours. There are additives you can use to help soil ph. Lime.epsom salts etc.. If you have a good soil mix you don't need to ph your water. My well water runs 8.0 and my girls are fine. It's all in the dirt. Good Luck!

I'm glad you fixed your ph issue and didn't take others advice and just feed more. now that you do have your ph corrected I would start of we're you were at 1ml feed glad your on your way to success.