I am always having trouble with the intensity of my LED grow lights during transition to flower and pre flower. Was told to keep it set the same as veg stage and just changing the light schedule will make it go into flower. Any thoughts on this?. So when I turn up the light it seems like it stops growing pistils and forming buds and when I turn it down it seems to like it and actually will see more pistils growing but I was told that I have to increase the intensity during flower so I’m not sure what to think about it. If someone can tell me what they have luck with doing during the transition to flower and pre flower stage I would really appreciate it. I have 2 150 watt quantum board LEDs that are from Amazon some Chinese manufacturer, it has 508 diodes on the 15"×11" board and 4:of them are IR diodes and 4 are UV diodes so that ×2 . I have them like 20 inches away from canopy and on opposite ends of the tent . Seems like the pistils retract when I turn the light up . Could these lights be more powerful than I think they are? They have a lot of the 660nm diodes also like a lot! Could that be a reason for this issue ? Idk I’m just stumped. Maybe too much heat? Idk please let me know if you can help point me in the right direction… Thanks
What I do is change to 12/12 and for the first week gradually raise the grow light above the canopy and power setting until your the right height and full power.
You should invest in a light meter. It can be as cheap and simple as a $30 LUX meter or as expensive as a good quantum meter around $600. Without a way to reliably measure the light output it becomes a guessing game based on how the plants are reacting to the light. I increase the intensity of light at the flip to flower and then go up each week of flower until I’m at the maximum amount the plants will take. Getting a meter will give you the data you need to adjust the lights at any stage of growth.
What do the manufacturer instructions say?
What do you mean you raise the light and intensity? Shouldn’t you have the light pretty far away in veg and then bring closer in flower? I don’t understand
It’s a trick with the growers that use the dimmers, I personally just run mine full blast start to finish on my indoor stuff
But theory is if ur running at 50% and crank it full blast then u can double the height and the plants will self adjust during the stretch so after the 2 weeks they are desired height with full light
LED lights are extremally photon efficient compared to HPS or MH bulbs. That means more watts are being converted into light photons instead of heat. You need to take into account DLI Daily Light Integral which basically means the amount of photons your plants can absorb during a given 24 hour period. Its a math equation where its photon density x time interval. During Veg you do not need as potent a light source (number of photons) in order to reach your desired DLI since you have 18 hours to work with. So thats why its recommended to dim the lights or raise them up to lower the intensity of light. In flower since you now only have 12 hours to work with but you want to maintain or even increase your DLI the LED brightness needs to be turned up to account for less time during lights on period.
I also recommend getting a light meter. I have an apogee ePar meter. Apogee is a company ran by Dr Bruce Bugbee who is one of the only scientists that allowed to study hemp by the government. He has done a ton of research into different light spectrums and light sources and their effect on cannabis. He is pretty much the godfather of cannabis research currently. Having a light meter takes all the guess work out of how intense the lights are at your canopy and its a must have in my opinion. If you don’t want the Cadillac version with the apogee (about $600) you can get a UNI-T LUX meter from Amazon for alittle over 30$ and its like 98% close to an apogee reading. The UNI-T reads lux which isnt exactly what we want but you can connect it a phone app called PPFD App and it will connect to the UNI-T through bluetooth, take the readings in lux and do the conversions to PPFD and maybe even DLI. If not just find a DLI calculator online and put in the PPFD number you got and the length of time and it will give you the DLI.
Edit: here is a video from Migrow on Youtube talking about the Uni-t and the ppfd phone app and how they work together.
I have the photone app but can’t get an accurate reading, I used a iPhone with the app and was able to get it around 370ish in veg but all the light selection are locked on iphone but not the android
Thank you @AzSeaindooin420 and @The_Lazy_Hippie for answering for me much better than I could 
This is how I set them up last time and dimmed 50% from the look of it only one is actually shining on the plant and the other looks to be wondering off to the side 
Closer together and horizontal may be better?
I’ve had trouble with these lights since I got them they throw off a lot of heat. The fan leaf stems will turn dark red and dry up and get hard almost like I’m cooking it.
Maybe raise them (2 or4?) and adjust your power to suit the plants.
I’ve just changed to leds I tend to grow quite shallow canopy. I get the lights as close as I can to the table like canopy. I would say I guet as close as three or 4 inches away. Then I dim The lights accordingly. Using a good light par meter I don’t know if this is the best way to do it, but that’s how I’ve been doing it so far
Do you have a bar light or quantum board?
Most modern LED’s are designed to run from 18"-24" above the canopy. Running them so close to the canopy limits the spread of the light. I’d try to get a cheap LUX meter to use to help you set them at 100% power or close to it. Running them closer but dimmed way down doesn’t use them as efficiently as turned up but farther away.
GR8 topic as I will be following along, need to know more about the LED lighting, intensity and distance in relation to the phases a plant goes through! 
I have both quantum boards and bars. mostly, I’ve been using the quantum boards on plants when they are quite small I like to use the bars when I’m flowering them I use a Apogee Par metre to make sure i’m getting my desired intensity by adjusting the dimmer accordingly
I realise the leds don’t shine down directly 90°. They are angled, so the light is cone shaped Therefore, as the light is raised The canapés footprint expands.
At the expense of using more lights, I don’t expand my footprint as much as I would, if I raced to the lights more and turned the dimmer up.
I do this because I don’t want to burn out my leds they don’t like getting hot I don’t know if this is a good way to do it but at the moment I can’t see any logical reason why I would do it different but I’m quite willing to listen to one’s logic that differs from this opinion because I’m here to learn