Is PAR/PPFD cumulative when using multiple lights on same area?

.Smoke

.Smoke

Well-Known Member
Hey folks. Have a HPS and CMH under the same reflector covering a 3X3.
When doing this how is PAR/PPFD figured?
Do you add together each lights tested output?

I.E.....Say HPS reads 300 by itself and same with CMH.
Does that mean you would have 600 PAR if the lights were placed together in this fashion?

Not rich. Can't afford a PAR meter atm :)

Help please!
 
What is the wattage of the 2 lights?
250 hps, 400, hps, 600 hps? 315 cmh?
Any pics of light? How close together are the lamps ?
 
Since both lamps are clearly not emitting the light from the same arc tube, your spot ppfd reading may not double like that but it will surely increase and you are definitely cumulatively adding to the total ppf for the space. Plus getting a fantastic spectrum :peace:
 
Moflow said:
What is the wattage of the 2 lights?
250 hps, 400, hps, 600 hps? 315 cmh?
Any pics of light? How close together are the lamps ?
Click to expand...
315w CMH+600w HPS/MH.
Reflector is 24"X9"X9"
20190929_134008.jpg

Thinking of upgrading reflector to this next weekend...adding the CMH at opposite end...this is 36"X32"ish...

https://www.homedepot.com/p/Hydro-Crunch-XXL-Open-Hood-Grow-Light-Reflector-with-Socket-and-Cord-for-up-to-1000-Watt-D940000600/302743290?cm_mmc=Shopping|G|Base|D27L|27-15_COMMERCIAL_&_INDUSTRIAL|NA|PLA|CommercialLighting|71700000052665286|58700005047601696|92700048545732754&gclsrc=aw.ds&&gclid=Cj0KCQjwrMHsBRCIARIsAFgSeI1KWem0kJqgYnW5kcPW94gwzRys7uIuuY8Qg3x3klovsEJ445wu5GAaAof2EALw_wcB
Screenshot_20190929-134234_Chrome.jpg
 
Last edited:
Renfro said:
Wherever the light "cones" overlap you will have a sum of both lights output. Angles of incidence will vary.
Really you don't need to overthink it. just total the wattage, run 50 - 60 watts per sqft and call it done.
Click to expand...
With everything cranked up I can run 100-122w/per sq. ft. Yay overkill!...
 
You must log in or register to reply here.
Back
Top