Light distance and Lux

[thesprinklerguy]

Hi all, new to the forum and just started growing again after 10 years or so. I've read everything on this site and I am blown away with the knowledge and advice given. I read about the lights and distancing from the plants and had my 400W MH light at 14" which was the preferred distance. Than yesterday I was reading further and came across an article about LUX and how much is right for your plants. The recommendations were min 40,000 to 80,000 lux, but leaned more toward the lower # 40,000. So, I went and checked at all 4 plant sites yesterday and found that to get 40,000 LUX I had to lower my 400W MH to 9" above the plants. It's only been 1 day but I do not see any negative effects of the light being this close, the leaves are praying but seem very happy.
These plants are very young still, planted seeds on 1/27 and moved to RDWC on 2/3.
My question is, if I see no negative effects moving forward, should I be setting the distance of the light based on the LUX, or the distance guidelines given for the MH bulb.
Strains are Zombie DF on left and Sugar Bomb Punch on right, both from seedsman. Using Flora Trio with Cali-Magic, current PPM is approx 300 and PH is at 6.04

Thanks in Advance

[YYCannabis]

Howdy Sprinkler! Welcome to GWE.

Seems like I’ve been saying this a lot lately so I’ll say it again...don’t measure light height from some chart or from what some manufacturer says to use. Growers need to watch their plant and not a measuring stick. The plant will show you signs of what they want. If they want more light, they stretch. If they want less light, you will see new leaves with deformed growth. If it’s too hot for them, they will curl their leaves.

New gardeners get bombarded with a bunch of numbers and metrics that are meaningless in practice, but sound great in theory or as a starting point.

Your little growing green monsters are your measuring stick and LUX/PAR meter. Watch them. Follow their lead and you will have great success growing dank smoke.

[YYCannabis]

Since you’re doing DWC I attached 2 pics that you will want to save and keep handy near your grow space. These aren’t related to lights, but become important to know on a daily basis.

Also I should mention that you will want to let your pH drift up and down in the range. Don’t peg the pH at a set level for too long or you can/will create deficiencies. It needs to fluctuate for proper nute uptake. 👍

[thesprinklerguy]

Hey thanks the reply. I guess I need to spend a little more time here now that I'm done reading just about everything on the site 3 times while waiting for my seeds. I was really thinking the same thing, until the plants tell me to stop, I'm going to give them as much light as i can. My old grow I had 2 of the 400W HPS/MH and shocked the hell out of myself with the yields I was producing after a couple grows, but unfortunately me and the ex split up and I lost the house and even worse, 1 of my growlights. Going to see what happens with just 1 and maybe buy a 2nd after the first grow.

Thanks again for the response

[thesprinklerguy]

Awesome thanks for the graphics. I'm familiar with PH and and making it range through for the intake of different nutes, but that 2nd one is priceless. Another reason to watch these boards, info I did not see on the site or anywhere else.

Thanks again, I'll be reading your posts a lot and try to suck up some of that knowledge..

[dphipps1020]

I agree with the above. The recommended distances are more of a starting point and your plants will tell you what they want. For an example, I have 4x Mars Hydro TSW2000 LEDs in my 8x8 and some of the lights are at 12" or less from the top of my plants while others are in the recommended range. Recommended distance for flower is 12-18". The ones in the lower range are loving the light and they're maybe 6-8" away. It's definitely confusing when you're just starting and going by recommended height but your girls are telling you different. And welcome to the forum.

[thesprinklerguy]

I have another tent with 2 x 2000w LEDs which I'm trying for the first time. I think actual wattage maxes out at 279 actual watts. Definitely not the best LED's as those plants are half the size and seem to have stalled. I've since read about the Mars Hydro and wish I read that info before buying them. Thanks for the response and glad to be here with the pros