Nutrient concentrations relative to light wattage


#1

I’ve been purchasing from ILGM for the past 4+ years but this is my first forum post. When I decided to convert a small closet into a grow room I decided on a 150 watt LED from Area51 (yes, this was more than a few years ago, they’ve been out of business for a little while now). The coverage was great for 2’x3’ floor space and heat generated was/is minimal. Initially I decided to go with a coco coir/hempy bucket set up using the Lucas formula and GH micro/bloom nutrients. Soon after that decision I read about the H3AD formula (modified Lucas for coco) and went in that direction. The results were great but there were some problems, namely the plants grew fast and very lush but at some point appeared to be suffering from nutrient burn/nutrient lockout issues. I made on-the-fly adjustments (without being quite sure what I was doing) and ended up saving things, the final product was great. Here’s a photo from about 4 years ago of ILGM Blueberry;

Notice how some of the lower leaves show damage from nutrient burn/lockout. The dumb mistake I made was applying H3AD’s GH 6ml Micro/9ml Bloom per gallon ratio for his plants under 1000watt HPS for my plants under my 150 watt LED. I’ve since made adjustments and have reduced my nutrient concentration by 47% from my earlier attempts (currently at 3.2ml Micro/4.8ml Bloom per gallon with minor supplementation of CALMAG). Below is a pic taken yesterday of an ILGM OG Kush at 2.5 weeks into flower. Some minor tip burn but nothing terrible, plants are overall more healthy than before (there’s also an ILGM Strawberry Kush growing next to the Kush);

Lesson learned? While it’s a great idea to learn form other grower’s grow journals and the various parameters of their set up, always be aware that if your set up does not largely align with theirs, adjustments will be in order. Cheers.


#2

I had a conversation some time back regarding TDS values in coco and got “schooled” on why high numbers aren’t necessary and often detrimental. I run between 800 and 900 ppm in veg and my plants look like they are artificial; they’re so perfect! (The wheels come off later lol).

Lighting can play a big part in liquid and nutrient uptake and load etc. What I suspect happened years ago; you were in a pot that ended up root bound, the PH crashed and issues developed. You were savvy enough to deal with it correctly.

Gotta love that OG Kush; one of the first strains I grew.


#3

I should have mentioned that the 3 grows previous to the one I’m running now, all were with nutrients concentrations too high for my set up. I took a TDS reading of my nutrient mix this morning – 462ppm – which is resulting in the healthiest plants I’ve grown so far. Along with light intensity, other factors obviously come into play as well when it comes to nutrient concentrations, i.e., humidity, temperature, and air intake and outflow in the grow room. For my small closet, inside air temperature ranges between 78F - 81F. Outdoor humidity is at 43%, likely lower inside due to my home a/c pulling some moisture out of the air. For air intake I cut a 3" diameter hole near the floor on the outside wall of the closet and ran a PVC pipe into the grow room. On the other end is a small attached fan that helps pull air in. On the ceiling of the grow room I installed an outtake fan that sends air out into my rather large attic (both intake and outtake are light tight of course). I don’t supplement with CO2. I’ve thought of replacing my 4+ year old RW-150 LED from Area51 with something stronger and newer, but that light is very efficient with all top bin Crees and has a good amount of life left.

The image below is of an ILGM Strawberry Kush. Unlike the OG Kush next to it which is showing some very minimal tip burn on a few leaves, the Strawberry shows zero signs of any nute burn or deficiencies. 2 weeks 5 days into flower with at least another 6 weeks to go.


#4

Yup! Someone once explained high TDS values this way: “They aren’t in the business of conserving nutrients!”

I run total numbers between 900 and 1,000 ppm in veg with 350 ppm in permanent water hardness.

You may want to look at what is being done diy with led’s: I built a full canopy coverage (720 watts peak) out of Bridgelux gen 1 EB strips and couldn’t be any happier.


#5

That’s a good suggestion. I’m a diy guy in a lot of ways but for some reason I’ve shied away from building my own light. I’m sure it would be a fun project and cheaper than any comparable commercial light I could purchase. And from what I’ve seen there are plenty of tutorials out there to explain the process. Thanks for the tip.


#6

Here’s the diy thread; it rambles at times but has some really good information. The hot ticket now are Quantum Boards but you can diy the strips to duplicate a QB at less cost. Especially if you have access to heatsink material.