yellowing leafs 4th week flower

dude i think alot of people over think this whole pot growing thing.. hypothetically, i would use nothing but shultz all purpose 10-15-10 all the way till flush 7ml per quart (as directed), and my guess is it would work greeeeeeeeeat... yellowing is very normal but your buds look very small. maybe inadiquate lighting for the bud size.. but if i were you I would find a good all purpose nute and use it all the way through till the end.. if it aint broke, dont fix it. just my hypothetical help. if its not dead yet, your doing something right. so get some schultz 10-15-10 for the next time, and call it a day. dont over think it.

just flushed em.
About to give weak mix of biobloom, a lickel biogrow, and canna boost.
......

gave em 0.75mil biogrow, 1.5 bloom, 1.75 canna boost (per Litre) Split 2 litre between the 4.

..................
dropped the 600w down 3cm to 67cm. (running a cool tube due to heat problems at start)

It ended up being PH. The F'ing PH probe I got from local garden centre was fooked. It thourght my water was 6.9..... lemon juice 8!!, and ph down went off the scale upwards!!

My waters PH is 7.7 to 8.0. So I was making it worse by flushing with high PH water.

Cheers Peeps.