Depressing fading / bleaching plants 4th week of flower.

Photo actually makes plants look better than they do in reality.
I had no other light in my grow room other than my 600w HPS which was masking the yellowing of leaves until the situation had become very obvious.
Things were going perfectly up untill 1 week ago.
I believe this is a case of underfeeding nitrogen - PH incorrect (or using malt vinegar as phdown) - light stress...
I've adjusted / corrected all these things but not noticing any improvement day by day as yet...
Other than the yellow leaves the whole plant is very pale and washed out looking (more so than the photograph shows)

What I'm noticing is that just before lights off they look very bleached out after 12 hrs of light, they clearly look their best at lights on after a long rest in the dark.. Making me think this relates to light stress. I've turned HPS down to 400w.

Anyone got any thoughts?

I'd guess ph, especially if you're giving them malt vinegar. What soil are you using and what are you feeding them besides vinegar?

I was mistaking using Fox farms big bloom believing it to be an all-purpose general feed, turns out is has extremely low NPK. Soil was Black Magic compost seemed great for the first 6-7 weeks. I checked run off water and it came out at 7.8 ph. Malt vineger was a temporary but recent change that did correspond to the time the plants raced downhill...

I've PH flushed them, added a fairly mild general feed with 3 nitrogen and an organic flower feed. Plus a dose of PK booster.
If they continue downhill out of my control (Hopefully not), what is the best course of action to harvest the (I know small) buds?

znjlewis said:

I was mistaking using Fox farms big bloom believing it to be an all-purpose general feed, turns out is has extremely low NPK. Soil was Black Magic compost seemed great for the first 6-7 weeks. I checked run off water and it came out at 7.8 ph. Malt vineger was a temporary but recent change that did correspond to the time the plants raced downhill...

Click to expand...

Big Bloom is actually the only FF nute I would use since I'm sticking with organics, but it is mild.

You want to get a grow formula. I started with Earth Juice Grow, Bloom, etc. And still use the stuff occasionally. It's actually what I started using lately as my organic ph down since I have a lot of calcium in my water which makes the ph rise over time. Usually I just give them plain water though.