Frist Grow Newbie w/ Yellowing Leaves

Greetings!

I just entered veg state with 6 plants, 4 ICE and 2 Aurora. Plants are about 2 weeks old grown from seed. The aurora's look fine but all 4 ICE plants have this yellowing on the leaves as seen in the pictures.

I am growing in rockwool doing manual hydroponics under a 600w HID. I am feeding them using the General Hydroponics and had been mixing the solution for a weak seedling and only just yesterday started mixing a strong solution for vegetative growth. Dutifully checking pH but using a solution kit, not a nice pH tester. Keeping rockwool damp, temps around 75F and humidity about 40%. i check my ladies 4-5 times per day.

The aurora's that appear nice and green are also significantly smaller. I find it odd that all 4 ICE's are yellowing and the Aurora's look nice (to me?).

From what I found here and else on the net this looks like "banding" and, to me, indicates a nutrient deficiency. I only just started feeding them full strength veg growth solution so it makes sense to me that the bigger plants (ICE) are starting to cannibalize itself.

Hoping some experienced growers can have a look and offer some advice! I would be very grateful.

My ICE was a heavy feeder, needing lots of N or it would yellow quickly. But I would wait for others to chime in, from those pics you could have a few other things going on.

And unless I am mistaken, N def. affects older growth first, so maybe not your problem after all. Maybe mg or fe def. Good luck to you.

I'm trying the same thing with rock wool!
Check out my grow journal. I tell how's going but
not on how to do it maybe I should but I've
had a rocky start too with low ph from my
preparing the rock wool I soak it too low
thinking that it's better! You did prepare
you rock wool with a soak of at least 5.5 ph
for 1 hour I do it longer. After the soak flush
it really good with 5.8 -6.0 so the runoff is
the same 5.8-6.0 YOU DID PREPARE THE ROCK WOOL?
It not this could be the problem!
It's real touchy~you need to be checking
your ph and ppm's with meters! I go by ppm's
like a plant your size may get 400 ppm's not a full
dose maybe a 1/4 dose. And you
really wanna let the rock wool dry out till
it dry and lightweight and the pot gets real lite!
This really stretch out the roots and that's
what you want!

>>>> YOU DID PREPARE THE ROCK WOOL?

I did, but per the instructions on the package *not* to soak it for a long time. Just till it settles to bottom. Which is a contradiction to what i've read countless growers say to soak (i've read ranges of 1 hour to 24 hours).

I strongly suspect I am loving my ladies to death. I've been keeping the rockwool very damp. Going to let it dry out like you suggest before feeding and see if it improves.

...and ordering a good pH tester!

You don't have to but for 1 hour just make sure it's like 5.5 when you soak them when you add the rock wool it'll go up to say to 6.0 something I add a little more ph down taking back down to 5.5-5.8 them give'em a good flush of 5.8. NO NUTES THE FIRST WEEK! Then maybe 200ppm's the second week going up 200 ppm's a week watering twice a week feeding every other watering get it? A lot of grower soak over night but it's not necessary if you stir it up good and add more ph down
keeping it at 5.8 them flush it good I use the growcubes and the Bulk rock wool they call absorbent or loose rock wool it has a lot more lime! Water~feed~water~feed! Here's a link that help me a lot

http://hydroponics101.com/sw62665.php

I'm growng BC Ice and it seems to need more Nitrogen. I had to start feeding it on the 2ns watering with in the 1st week of planting the seedling that i started in jiffy pucks.

Another update... just reading over the instructions of my nutrient mix by General Hydroponics and I have been mixing it wrong which could lead to nutrient lockout.

So today I flushed the plants with a pH balanced water. Going to let the rockwool dry out and then resume feeding albeit a bit less often and see how they do.

I thank those who thus far have contributed and I am very grateful.

24 hours after flushing with rockwool with ph balanced water and most of the yellow is gone and the girls are looking very healthy again. easily see several mistakes i've been making!