switching lights during flower (panel to cob)

I am currently flowering under a viperspectra 450 "200 watts" with additional reds (630) via 2, 24 watt e27 bulbs and will be switching it out with 2, vero 29 C at 100 watts each (timber 2vl).

The switch will likely take place early in the 5th week of flower. Looking for any advice or experience that will help this to be a trauma free operation.

I plan to start a little high, maybe 18-20 inches (the viper is at about 11 inches). I have a app with a lumen meter, (I know this isn't the ideal way to measure the output but it's all I've got at the moment) so I can try to match lumen intensity with the dimmer and then rachet it up as the situation allows, getting to full power before i start lowering the light. Does this sound like a reasonable plan of attack or are there other things i should be considering? How close should I be able to get to the canopy with the cobs at full giddy-up?

The plant is doing really well considering what I'm working with and I really don't want to screw the pooch this late in the game but I also know that the cobs are far superior and want to take advantage.

Thanks, G

You should watch your plants really close, all day the first few days. See if they show any sign of stress. Last thing you want is to bleach your plants in 5th week of flower, they wont like that. They wont die instantly either, but you will stress them. I would check in every 5 minutes if I dont have a camera view in there. It can be done, you just need to watch them really close

You got the right idea by putting the cobs higher, if you can't watch them close the first day put them higher then 20"

Thanks for the input Unaqi.

So with all the peeps switching to cobs no one here can share any practical experience? This switch makes me nervous, even more so after Unaqi's comments. C'mon now, help a brother out!

I think matching light levels with the lux meter will do the trick. Assuming light intensity is the issue the difference between lux and PPFD should be minimal for this purpose. I've seen small plants in veg switched from a 150w HID to a 200w cob led wither to nothing. Light was probably too close in addition to the output being much higher. It's may be possible the problem was compounded by the cut being several generations down the road under the same light setup. New seed/clone material would probably have less tendency to react poorly to abrupt changes in lighting scheme... just a guess though.

It takes a lot of light intensity to bleach a plant. If you start the light 18-20 inches above the plants the possibility of bleaching is basically zero.

Being nervous isn't a vad thing. I'm sure it's the reason my first grow had a succsessfull harvest. You will pay more attention because of it. @Rahz is more than qualified to answer any questions you may have and has given you solid advice

I'm sure you will be fine! Just making sure you are aware of the possibilities should you put the lights too close.

Unagi