Help Lower leaves yellowing and curling up (pics)

Hey guys i'm pretty new too all this. I have 4 unknown plants germinated in papertowel/plates about 3 weeks ago...

3 of which are very sick. I had them growing in just some all purpose mix with about 8 of the whatever little yellow balls are in the photo.
About 2 weeks in I had a plant fall over (to big for own good) so i topped them all up with some soil from my actual tomato plants. Ever since I done that, they've started yellowing
Are covering the lil' balls bad? Or Could it be the soil from my tomato plants as they are in metal pots with inner rust.

I've just transplanted them yesterday into a soil i made with compost and Yates tomato potting mix with dynamic lifter. (see photo) 
Soil PH is around 5 1/2 - 6  ...may be wrong :\\

First 3 weeks i had them under a blue 100w grolite at about 1-2 feet away with a 100w CFL
at about 6-8 inches away just for overnight whilst it can get a lil frosty overnight here in canberra, AUS.
...I've discontinued this use 

I heard maybe nitrogen deficiency so i bought this "vita sea plus for vegies and herbs"
and too raise PH "dolomite lime"   contents for these are in photo.

This is a link of contents in my local water supply:
www.actew.com.au/Water%20and%20Sewerage%20Systems/ACT%20Water%20Supply%20System/Water%20Quality.aspx
 
Parameter Typical value ADWG (health)
Note: These values are based on water quality data reported in 2011-12.
pH
7.7
6.5-8.5*
Alkalinity
36.0 mg/L as CaCO[SUB]3[/SUB]
-
Colour (true)
<1 Pt-Co
15*
Turbidity
0.34 NTU
5*
Fluoride
0.82 mg/L
1.5
Hardness
44.4 mg/L
200*
Iron
< 0.02 mg/L
0.3*
Manganese
0.004 mg/L
0.5
Aluminium (acid soluble)
43.12 mg/L
200*
Copper
0.02 mg/L
2
Lead
0.0004 mg/L
0.01
I'm especially worried about the one with not two, but three cotyledons as i hear they yeild 30%
more than the others.

Any help on what else i should add, how much of what i should add to these 10 litre pots would be awesome!!!