Flood and drain problems, sick plants help plz

[CGM]

Ok im new to this flood and drain system and im having some problems.
Heres some info along with some pictures:

Veg:
2 - 600w
5ft x 7ft table
medium = rockwool cubes 4x4x4
temps = 27C day, 18C night
Nutrients = Advanced Nutrients 3 part + grozym
(vegging for 2 weeks, week1 300ppm, week2 500ppm)
PH = 5.5
Im watering them every 48hrs from the top with a hose and draining to waste.
These plants are 16 days in veg due to the problems im having.

If you need anymore info. feel free to ask.

 

[CGM]

also i tested the ppm and ph of the water in the rockwool and i got a reading of 640ppm and 6.2 ph

 

[Sauron The Blue]

how do the roots look on them? almost looks like lockout from overwatering

 

[brainlab]

not a hydro guy but as sauron says ... those cubes hold alot of water , and whit small roots 48 h seems a bit to often.

hope it goes well.

 

[CGM]

Yea i think i did overwater them, i hate rockwool

 

[pandabear]

he hey CGM

i lost your details that you gave me,...

uk cheese boy

keep in touch

 

[Abja Roots]

Have had similar problems since switching to hydro. Basically since you're handwatering you can gauge it on your own. If the roots are not exploding out of the bottom of the cube I normally don't water more than every 3 or 4 days as necessary. They just don't seem to need it and want to stretch and grow more to get out of the cube looking for water.

I would say from the drooping leaves you guys hit it on the head. I hear you about the rockwool but I like that it seems to give the plant a firmer center and a stronger base. Rather than just putting it straight into the medium.

Good Luck.

Does the ph seem a bit high to you in the cube?