Dark spots/dieing leaves with pics HELP

Hey,
im on the 4th week of flowering and ive been getting these datk spots on my leaves, they they curl up / dty out and die.
Please help me solve this problem.
ive been feeding them bio-bizz bloom 3-4ml per liter.
il tell you the ph tomorow as they are currently sleeping.
thanks for all your help.
will put pictures in a minute

could bee mold but theyres no pictures,,,,

Probably a phosphorus deficiency. Or could be mold.
Post some pics. If it's a p deficiency fix your ph, or feed them more.

heres some pics

so ,,, anyone know whats going on?

i'd like to see how this turns out

so ,,, no-one?

come on guys ,,, i really need you help here

are you growing in dirt? or hydro? if your growning in hydro try to flush it, it looks like some pestaside.

well ,,, today i watered and it think i figured it out... the soil ph was 6 and the run-off was 5.3.
tomorow i shall go into town and get some oyster shell to raise the ph, of phosphoric acid if i can find it.
can too low of a ph cause this?
thanks

i've had two different sets of plants do this. They always start at the 3rd or 4th week of flowering...i think you may be right about the low ph because thats what i suspected cuz my nutrients reallly lowered the ph...anyway it was kinda too late when i diagnosed it(7 1/2 weeks) but they still seem to have recovered a small amount...anyway keep us posted and if you can post some pics if they recover/get worse...greatly appreciated