Lighting watts per square foot question.

[1guy1plant]

Not over thinking it went out the door about 2 months ago when I stop the space bucket build about 2/3 of the way through and built a grow box with a bunch of under powered computer fans, to put in my closet. Then I decided, screw the grow box, I will just convert the closet and some how ended up with 22sqft of grow space that needed to be lighted and ventilated. This weekend I will finish building falsewalls in closet reducing space to approximately 9.5 sqft. My 6 inch fan/filter was delivered today, so I will install that. Not to mention I cannot even sleep at night worrying that my ph levels are out of whack bc I only spent $20 on my ph meter.

I use to be into RCairplanes. This is a lot more fun.

With all that, all I do is smile about that my 3 auto bluemystics are at the end of day 3 and each one has two sets of leaves. J I appreciate all the advice. I cannot wait to get a few grows under my belt.

 

[natertots]

There is some cheap ph stips on amazon that does like 5-8ph with increments of 0.1. Comes in handy, 5.8 is easy to see. Make sure u look at pics of it though if you go look cause first strips I bought the colors were to close to each other and I couldnt tell 4 from 8.....the same measurements I needed to calibrate my cheap meter. Mine came in a tape form and was like $6 or $7.

 

[jackmc]

1guy, I am using a $8 PH meter from Amazon. Just get some calibration fluid. I use 7.0PH fluid. Even a $10,000 PH meter won't tell you anything if it's not calibrated. Peace

 

[pop22]

I really hate to disagree with you but you can have to much light.this is most obvious with "led burn" to much light will shut down chlorophyll and could destroy it. lighting levels could be higher with HPS because of the spectrum they produce and the weighting that spectrum gets on the lumen curve (http://www.carbonlighthouse.com/2014/02/13/683-lumens-per-watt/#prettyPhoto) but with fluorescents 4000 lumens per sq ft is consider.ed optimal and with led 40 to 50 watts (actual power) is very common.many plants actually shut down in mid day to protect themselves when grown outdoors and the lights we use tend to have a more focused spectrum than sunlight especially with leds

Lumens are not a very good way to judge your lighting for growing. Lumens is like a a gas guage, it tells you the total amount of energy in a given area. but PAR is much more important. ( Photosynthetically active radiation ). PAR designates the spectral range (wave band) of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis. A light meter will tell you how good your reflector is at distributing light by pointing out light concentration at specific points.
Even the concept of measuring Wats per sq.ft or sq,M is meaning ful only when comparing similar light technology, ie, Metal halide with Metal halide. the PAR of LED lights can be as high as double that of HPS/MH. Take my 300 watt LED lights. They have an actual draw of 185 watts. The coverage for one light is about 2ftx4ft for 8 sq.ft. giving 23.125 watts per sq.ft.. Yet I'm willing to bet it will give the same results as a 400 watt MH if not better. a 400 watt MH would give the magic 50watts/sq.ft. Having used the LED for some months now, I can say that the 2 I have produce about the same results as my 600 watt MH did. Why? Because of the high PAR values it has.An LED is not wasting power on unneeded spectrum.

As to too much light, I've read that with HPS/MH your plants are maxed out at about 70 watts/sq.ft. The whole issue needs a better way to figure all this, sadly, there's no standardization, so we end up reverting to the very general"watts/sq.st.

 

[derek420colorado]

Lumens are not a very good way to judge your lighting for growing. Lumens is like a a gas guage, it tells you the total amount of energy in a given area. but PAR is much more important. ( Photosynthetically active radiation ). PAR designates the spectral range (wave band) of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis. A light meter will tell you how good your reflector is at distributing light by pointing out light concentration at specific points.
Even the concept of measuring Wats per sq.ft or sq,M is meaning ful only when comparing similar light technology, ie, Metal halide with Metal halide. the PAR of LED lights can be as high as double that of HPS/MH. Take my 300 watt LED lights. They have an actual draw of 185 watts. The coverage for one light is about 2ftx4ft for 8 sq.ft. giving 23.125 watts per sq.ft.. Yet I'm willing to bet it will give the same results as a 400 watt MH if not better. a 400 watt MH would give the magic 50watts/sq.ft. Having used the LED for some months now, I can say that the 2 I have produce about the same results as my 600 watt MH did. Why? Because of the high PAR values it has.An LED is not wasting power on unneeded spectrum.

As to too much light, I've read that with HPS/MH your plants are maxed out at about 70 watts/sq.ft. The whole issue needs a better way to figure all this, sadly, there's no standardization, so we end up reverting to the very general"watts/sq.st.

I think there is only one way to settle the debate, use both lol. That is what I am going to do on my next run, and when my house is built in the spring I will be using all 3 types of lighting, The natural sunlight(it will be in a green house), HIDs, and LED's I think that with all 3 types I can't miss