Hi,
I have a 350w diy cob unit and I am trying to figure out the optimal height to keep the light at. Its on a pully.
What wattage unit do you have and what is your lux at canopy level? How far is your light from the plants.
My light drops down to 30k lux around 6 inches from the light. At around 20 inch away lux is about 8k. The cobs I have are each giving out 7k lumens x 7 cobs @ 50 watt. I should be getting 49000 lux over one meter square. Which is equivalent to a 400w hps.
Im wondering do hps users experience the same kind of drop at distance from the bulb or if somehow the intensity is better despite emitting the same amount of light.
I've used a lux meter since day 1 as a guide. I know flouro to hid to led isn't 100% comparable, but I watch how my plants respond and use lux from the source to dial in a sweet spot.
Yeah, it can drop off, but ideally you will have some depth to your intensity. Like getting 60,000 lux at the top of the canopy to 30,000 lux at the lowest buds.
I've found 25,000-30,000 lux for young plants works ok. 30,000 - 40,000 for 4-8 week veg. 35,000 to 60,000+ in flower.
If your light needs to be 6" away, you are going to be putting in constant work to maintain light height, and you are not going to get good growth lower without the penetration power.
If you are using a phone app, I'd probably opt for a cheap Amazon meter for some reliable results. Yes, a PAR meter would be best, but I've always had better things to invest in.
I use COBs in veg and verify my distance with lux. I just setup a dual bulb hood in my flower box with a 315 CMH and 400w HPS. 30,000 lux at the floor (4') and 60,000 lux at 2', pretty happy with that.
