Pls help needed!!! Plant problem!!!

Hi to everyone
Desperatly need an a advice with my plant. Allready been through many different opinions, articules and so far nothing, which left me confused.Basicly problem is with my leafs which become yellow and brown.
Nutries:
bio bizz bio bloom bio grow 4ml/1l
PH 6.6
watering:
twice a week
light:
400w HPS
grow room:
50/90/160 cm
temperature:
23-30 *C
AGE:
5 weeks old/ first week of flowering
I noticed first yellow edges of leafs around 5 days ago, then they started to dry...
So far i flushed them 4 days ago, waited for the soil to dry and then started with 1/4 dose of nutries and BIO BIZZ "ALG-A-MIC" per litre.That helped a bit but whole plant isn`t as green as before.
Thanks.

Looks to be all around hungry. Definitely getting Magnesium deficient. I would hit them with a good dose of veg nutes if I were you....and always finish a flush with a feeding. Unless you flushed because of nute burn.

Yes if your going that low I would agree you need to feed them right around full strength..

I would get some calmag too, or those yellowing leaves are gonna get worse

when you say ph 6.6 what is 6.6 the water your adding into the soil? make sure the soil ph is ok.if your using good nutes you should have any deficiencies unless the plant cant use the nutes.

except calmag... lol I have yet to find a flowering food that provides enough. Most common posts on this section, " help 3-4 weeks into flowering and leaves yellowing"