If I change the bulb from 6000K to 2000K and use t...

2000k might be too "warm". Other wavelengths are still important and not just the red ranges. The other thing to consider-- plants adapt to the light the receive. So the pigmentation and such adapts to CCT and intensity. If you drasticalyl change the light provided, that potentially has some drawbacks if you do it midstream... probably small effects that are diffiuclt to see with eyes and not tracking large samples while freezing other variables and having a control group for camparison to make a rational assessment on such a thing. Don't over think it. 6000k and 2000k are probably both too extreme regardless of whether you use them in vege or flower and the effect of it is virtually impossible to recgonize with your eyes. no matter what, some reconfiguration over time will occur in the leaves and that has a cost of 'something'. wehther it is outweighed by some other benefits is not something any human can resolve by simply doing it with a few plants in their home and wildly variable environments etc. these people are just lying to themselves and reinforcing existing long-held beliefs regardless of shoddiness of evidence used. like mouse said, focus more on providing proper levels of DLI and then play around with CCT options after that need is met.

Yeah going from MH to HPS for flower is perfect. Plants life cycle wants white light seedlings then blue then red in flower...

Maybe? 6000K and 2000K refer to the colour temperature of the light, but spectrum also matters and how much DLI its getting and that's somewhat related to watts its pushing on the style of light. Eg LED, HID "hps,nmh,cmh", floressent, exct. You will want to let us know the bulbs/light your using. Seems in you diary it is a mix of HID and then a LED bulb that fits in a HID lighting setup for some backwards compatibility. I would just use HPS and CMH for the two options in hid lighting. CMH in Veg, and HPS in flower. If you want to switch over the LED I think its best to get a full LED lights not something that fits into the old equipment. Bar style LED lights seem to be the best option right now, good coverage and value. There are some cheaper LED options like Qboards and they work well but do tend to have hot spots. Then theirs the really old LED style stuff that's blue/red and they should all be avoided. I don't feel that LED that's being used is great but did not look into to much. A few people on here really know their lighting facts and are quite smart. If you really want to upgrade your setup, post a question asking whats the best and give a tent size and price range your willing to spend. No doubt they will come out. One of them has a username made of all numbers. 0's and 1's In the end if DLI is getting hit, it should be fine, but I feel its not and I would avoid LED compatable builds in a HPS setup and just get the HPS bulb for flower. Wear gloves when handling them. your finger print oils and salts and lower its life span.

Hi yes the switch to 12/12 is OK but the most strains in the flowering phase, need around 60,000 lux. It is important that the light source is not too close to the plants to avoid burns. You can use the app Photone to adjust your light I usual use in flower an PPFD value from 900 to 1000 µmol / (m²s).

Yes, if you're planning to switch to 12/12 for flowering then it's a good time to switch your bulb to the red end of the spectrum.