new leaves are yellow, ph problem?

Hi,

This is my first grow and I am having some trouble. Please help!
Germinated a few seed in separate times to avoid repeting mistakes and followed the instructions of the dude that sold me the tent, equipments etc...

Germination was easy, moved the seeds to Jiffys under a fluorescent light, only water with pH at 5,5 as instructed.
For one week everything was ok.
On the second week, I started to notice some yellowing on the inner part of the first 2 leaves on some of the seddlings.

With time the issue persited and agravated, the same dude told me after I sent him the pictures that it looks like N defficiency, so I added fertilizer (half dose).
It helped but after a couple of days the yellowing started again.

I did some research and read that for cultivation in soil the ideal pH would be from 6-7 so changed it to 6.4 instead of 5.5.

I noticed some improvement but the tip of the leaves got burnt.

My speculation at this point is: pH 5.5 was too acid and was stoping the plant from getting nutrients, after ph correction nutrients became available and it was too much.

So I have now watered with only plain water with pH 6.4.
For the past 48 hours i saw no improvements but burning seems to have stopped.

I guess what I am looking for is some guidance on:

Are my assumptions correct regarding the pH?
What is missing from an ideal environment?

See some pictures attached.

Details:

-Light:
HPS 400W (1 meter distance)

-Nuts (Half a dose):
Cannazyn
Rhizotonic
Terra Vega (Canna)

-Temperature:
24 C light time
19-20 C dark

-pH:
6.4

-Vase
1L

-Watering:
every 4/5 days

How old r they ? I wouldn't give them any nutes for the first few week they will burn. I PH between 6.0 and 6.5 and never had any problems. And the pots too big 10cm pots are fine to start with but 1ltr is too big.

what kind of soil are u using and are you letting them dry out good before watering? I have run my nutes at 6.5 with no problems
YEah giving them nutes at that stage of growth can screw them up, especially if overdosed. Those leaves do look a little crispy.

RELPHY82 said:

How old r they ? I wouldn't give them any nutes for the first few week they will burn. I PH between 6.0 and 6.5 and never had any problems. And the pots too big 10cm pots are fine to start with but 1ltr is too big.

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The plants are now 4 weeks old and have been on the 1 L pot for 2 weeks. Do you think the problems might be related to the pot size? It does take about 5-6 days to properly dry out. I usually water a little before that.

green217 said:

what kind of soil are u using and are you letting them dry out good before watering? I have run my nutes at 6.5 with no problems
YEah giving them nutes at that stage of growth can screw them up, especially if overdosed. Those leaves do look a little crispy.

Click to expand...

I use a lightmix soil (soil pH @ 6.5) and it does keep moisture for a while, perhaps they will benefit from letting the soil dry for a little longer.

Will water then in longer intervals and with water only for the next week and see if there are improvements.

At that young age I don't even worry about nutes. You should get that soil wet and then not touch it for a good long while. Problems this early are almost always over/under watering.

I water once when the seedling emerges til water comes from the bottom of the pot. Then I keep my hands off for at least a week or 2. It has little roots to suck all that water up.

way over watered u say almost 4 weeks old?

If your seeing issues on new growth ot top of plant your issues are micronutrients if bottom and works its way up is macro plain n simple
As for new seedlings soon as there are roots the plants are ready for nutes in ery light proportions yellowing can be from to much watering and not enough nutes there is a fine line use a syringe for new seedlings this way you never over water

thumper60 said:

way over watered u say almost 4 weeks old?

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because it is one of the most common mistakes made. I have done in the past. I have learned that letting my pots get real dry or light to pick up then water.

I start mine in 10cm pots for the first 2 week then pot them up. Only give PH 6.5 water for first few week coz nutes will just burn them. Let the soil nearly dry out before u water They look really small for 4 week old ! Here's mine at 5 week from seed.

RELPHY82 said:

I start mine in 10cm pots for the first 2 week then pot them up. Only give PH 6.5 water for first few week coz nutes will just burn them. Let the soil nearly dry out before u water They look really small for 4 week old ! Here's mine at 5 week from seed.

Click to expand...

I love leafs with 11 fingers it's a very happy plant

over watered, soil should be moist not soaking wet etc