Low light at base? I don't think it should be

Hi. I have 7 strains going in a 4x4 tent.. 5 gallon pots. Feeding botanicare soil pro. Feeding every second round with phd water in between. This issue started a week after flipping to 12/12. The lower section of these plants are dying off. Not sure why I just upgraded the lighting to spydrx plus. I was worried it might be too much but now I don't know what to do. Any help would be appreciated. Thanks

Anyone? I really need to know see if I can pull a bit more quality from this run. Plus for the future going forward. I'll be moving to a perpetual run hopefully. The other led I just got for the second tent is hlg-550 v2. Any tips for that light for harvest would also be appreciated. In the future I think I will cut back on the vegetation length and flip w9the hit no more than 24" in height. Help please.

I think they look light on nitrogen and could be a lot less light at the bottom of your canopy, the last pic they look really good . I really don't see any dark dark green anywhere. So I Might try and give them a bit more nitrogen for now see what happens. I am using leds myself and mine have no problem getting through the canopy and I have not had that issue. Did you do a ph test ? start there and then maybe try to give a dose with a bit more nitrogen, I am just guessing because there's not enough info.
Ph, Ro or not. Soil, temps, RH. and anything else your doing.
good luck hope you get her figured out before anything bad happens.

I think its a combo of overcrowded and low N

You need to practice better canopy management. Keep those tops lower and then your whole plant is more spread out horizontally and the light can be closer. Super cropping would help.

Thanks for the replies. I checked the soil ph and it is a little higher than it is normally at 7 even. I aim for 6.5. That said I don't think it should be an issue here. A little more information on environment and such: ro water. Ph to 6.3 and it usually creeps up a touch. Soil is farfad agro. Temps are between 74 and 83. I've added a few co2 bags to help with the heat and what not. Feeding botanicare soil pro line with cal-mag,silica, karma,sweet raw, hydro guard. Humidity is 50 -55%. I've added a bit of N for this next feed but I don't want to stunt the flowering that's going well at the top. As for Canopy management, I had topped all of these as well as using LST with twine but once the switch to flower was made the growth was ridiculous and the twine was starting to cause issues. Once I cut them I couldn't redo it as the branches had hardened quite a lot. Next time I'll know which will have the greatest stretch and I'll be able to compensate. Thanks again for the help guys.