White label - White Diesel w/pics - 5th week flowering NEED HELP URGENTLY PLEASEEEE

hi folks, hope all is well, just need some help please

what i got:
using biogrow, biobloom nutes,bio bizz all mix soil
250w hps, mylar

i havent been using ph tested water, but usually leave it 5 days before using the water. and they are on 5 ml bloom 2 ml grow. also no ventilatation in the cupboard and does get fairly hot but just added a small fan so hopefully this will help.

Basically the plants are starting to go a much lighter green and some leaves completely yellow, im worried this will slow the growth

please any advice and help much appriciated in this late stage,

i wanna save my beauties

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usually yellow means nitrogen deficiency

dosnt look to bad

yeh, i flushed them today, and gona see if it was nutrient lock out due to the ph of the water, hope they perk up. will post more pics tonight