Par watt importance?

I picked up the new lumatek 1000 watt with something like 1700 par watts. I decided to try it out for my first bulb for flowering. So far i've had some very good growth. Does anybody else use these or know much about them? I'll keep pictures posted in my journal too keep whoever is interested posted on my project.

PAR stands for Photosynthetically Active Radiation which is the part of the light spectrum which plants respond to, roughly between 400 and 700 nanometers. Because of this and considering that plants respond differently to light than humans, the way bulbs are typically rated (in lumens or lux) is a subjective measure which doesn't apply equally to plants.

For example, a high pressure sodium bulb appears to emit more light, in terms of lumens, than it's metal halide counterpart; but a metal halide usually emits more PAR or light that plants respond to. Therefore PAR watts is really an objective measure of the amount of light energy emitted by a lamp which plants will actually respond to (between 400 and 700 nm). Although, in terms of PAR watts a 1000 watt lamp wouldn't be putting out 1700 watts of PAR- 400 PAR watts seems more accurate (in other words the PAR Watts really couldn't be more than the bulbs actual wattage). Another way to measure PAR is in micromoles of photons per sq. meter per second and the 1000 watt Lumatek high-PAR HPS is listed at 1,798 PAR (umol/s) which is what I believe you're referring to.

http://www.sunmastergrowlamps.com/SunmLightandPlants.html

Thanks for the info Nullis. Very helpful. Two weeks into flower on my first crop and they are looking great. Explosive growth so far. Thank again +rep

I'll '+ rep' that, as well. Good info.

Nullis said:

PAR stands for Photosynthetically Active Radiation which is the part of the light spectrum which plants respond to, roughly between 400 and 700 nanometers. Because of this and considering that plants respond differently to light than humans, the way bulbs are typically rated (in lumens or lux) is a subjective measure which doesn't apply equally to plants.

For example, a high pressure sodium bulb appears to emit more light, in terms of lumens, than it's metal halide counterpart; but a metal halide usually emits more PAR or light that plants respond to. Therefore PAR watts is really an objective measure of the amount of light energy emitted by a lamp which plants will actually respond to (between 400 and 700 nm). Although, in terms of PAR watts a 1000 watt lamp wouldn't be putting out 1700 watts of PAR- 400 PAR watts seems more accurate (in other words the PAR Watts really couldn't be more than the bulbs actual wattage). Another way to measure PAR is in micromoles of photons per sq. meter per second and the 1000 watt Lumatek high-PAR HPS is listed at 1,798 PAR (umol/s) which is what I believe you're referring to.

http://www.sunmastergrowlamps.com/SunmLightandPlants.html

Click to expand...

So what your saying is a good reputable company like lumatek is lying to us?

i dont think they would publish something that could not even be a possibility. thats just ridiculous

where exactly did you get this info?

Umm...not...at...all? Sorry, but you might want to try giving that a more comprehensive read. What I am saying is that Lumatek apparently rates the PAR-emission of their bulbs in terms of µmol/s or micromoles of photons per square meter per second. This is a measurement of the actual number of photosynthetically active photons (the most basic packet of light energy which the plant will absorb) that are falling on a square meter of surface each second. A µmol or micromole represents [6 x 10 to the 17th power] photons; lots and lots of photons. In the case of a 1000 watt Lumatek HPS bulb, the PAR is listed as 1798 µmol/s. In short, this is a different type of measurement than PAR in watts.

Wattage is a measurement of the amount energy used or emitted in a given frequency (a second). A basic unit of energy is referred to as a joule, and a watt is equal to 1 joule per second. A 1000 watt bulb uses 1000 joules of energy per second. A great deal of this energy is lost as heat; it doesn't all translate into light and not all of the light emitted is photosynthetically active. Those watts emitted by the bulb which could be utilized by the plant are the PAR watts. The PAR wattage of HID bulbs is generally 30-40% of the energy consumed. A bulb could never have a PAR wattage that is greater than its operating wattage, it just isn't logical. The link I provided in my previous post explains all of this stuff and more quite fantastically.

http://www.bghydro.com/BGH/itemdesc.asp?ic=HLRBHPS10LTK - Lumatek 1000 watt high PAR as advertised.
http://www.4hydroponics.com/lighting/sodiumbulbs2.asp?ItemNo=lumatekHighPar - Other Lumatek bulbs.

Here is another bulb retailer. Note the PAR wattage given for the bulbs and compare the PAR and lumens of the metal halide to the high pressure sodium.
http://www.tcs-hydroponics.com/doc/lightbulbaccess.htm

okay i get it now... lumatek is not saying that there 1000 watt bulb has 1,798 par "WATTS" there saying there 1000 watt bulb has 1,798 µmol/s...

so is there such a thing as PAR WATTS?

if there is what would the umateks be at