Lighter colored leaves at flowering sites

Might be too much light or cal/mag deficiency in my opinion. When I see the younger spots in light green I increase or start giving cal/mag and it disappears if its not too much light

@00110001001001111O , I disagree about a marketed 4x4 light being placed into a 3x3 being bad in general, that would be a beautiful thing and make most participants see instant movement towards better quality flower and longer equipment life. old school rule of thumb was always always always a 1000 watt hps in a 4x4. do your math out on efficiency changes, and a 400W led in a 3x3 is basically chef's kiss perfection to put you right at the old 600W draw hps in a 3x3 rule of thumb. at the same time though...his diary has a 300W and an 800W LED fixtures with modern efficiency ratings...so idc where his 400W one is... i think green claws might be onto something but with the degree of the color gradient going on, youd have to presume something is happening. double check your environment, get it stable. so a clean nutrient swap, taking the time and care to manually validate that each step is done in appropriate organic chemistry-driven order. small things matter over time in a run. like your nutrient solution is having contact with light every time it comes out of your halo emitters... cover that. another thing is that you arent tracking your solution temperature. you should look at some basic charts like 'oxygen saturation in water plotted by temperature' and 'nutrient availability in water by pH'. theres a lot of stuff that water has to be doing, it has to change and hit the right points at the right time, while staying in a temp and O2 and nutrient range. then add in the fact that we only see a really crappy view of our water. we'd all love a list of ions and concentrations, but we have salinity temp conductivity and solute. tough game new growth only is your starting point on a dich. key if it is not environmental. plant prioritizes new growth, so a lacking of something there means that on a biological level the plant is unable to overcome this hurdle even by cannabilizing itself. also EC 3.6???? good lord

Lack of nutrients can cause yellow leaves like yours. Ph is the last thing I assume unless it’s growing in hydro

you're at the early flower stage, did you drop the nitrogen back to far to early?

400w in a 3x3 space, give or take? Was probably the light. As far as guesstimating proper power, totally depends on how accurate that spec sheet is, otherwise it's 100% you fucking around with height and power until it the plant grows properly without symptoms. I'll assume you can choose the hanging distances based on light distribution? with a light like that, probably 20-24" is a good idea. QB, cob led and those older smaller framed lights need more distance. For 18h, you only need 56 umol/s PAR per sq ft. This is where the spec sheet comes in. Multiply your total umol/s PAR needs. 56 x sq footage of canopy. Take that total and divide by max umol/s PAR output of the light. That is your starting power percentage. Minor adjusments will always be needed, because "max" DLI is a moving target unless temp, rh, and ambient co2 are all tightly controlled. Regardless, it's a good start with minimal adjustment needed, assuming the spec sheet was accurate. Read up on Daily Light Integral and PPFD, if you want to understand how to properly measure and compare light provided to a plant. Should be easy to extrapolate the why of everything said above. Learn to fish.