Think my plants are dying?!?!

what up? im first time grower.
was vegged for 2 months on slow release fertilising soil.
strain=feminised big bud
lighting=400w HPS
have four plants at the moment
Medium=soil
nutes=bio grow(vegging)8-2-6,bio bloom(flowering)2-6-3.5
been growin in an attic.
light is about 15 inches away from plants.
gets bou 15 degrees when lights off.when lights on its about 20-25

ive just put them into 12/12 4 days ago
my only problem is the bottom leaves are slightly curling and turning a bright yellow colour and on my other one i have rustic looking spots on the bottom leaves.any one got a clue on how to fix it?or is it nothing to much to worry about?.will it affect the buds at harvest?.pics below.ask questions for more info if u think u can help out.

looks like a N def.

you didnt specify yur pH? do you know it??

no thats another problem i cant get my hands on a ph meter..any advice on what i should to with my plants?

TheGanjaFarmer said:

no thats another problem i cant get my hands on a ph meter..any advice on what i should to with my plants?

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fertilize your plants with a fertilizer high in N. so like 10-5-5 or 20-20-20. aslong as the 1st number in the N-P-K ratio is high your fine.

use 1/2 reccommended dose and watch your new growth for improvement, and watch the healthy parts of the plants above the damage. if it stops spreading, and the plant is growing new healthy leafs your fine.

the damage you have already wont fix itself, it will stay yellow, just watch the healthy parts of your plant to see if you can notice "spreading"

this looks awfully familiar as i am also growing big bud.hmmmm maybe its a cockinurass-deficiency.yo stay toking nigga

if you do not have a ph meter then you will have problems down the line because of nute lock out

you could always get the ph strips if you cant afford the digital ph meter. dont waste your money on a cheap digital meter either if you plan on buying one.