If the Rule is 50 watts per square with a HPS ,…How would you know if your plants are getting the 50 watts, or more or less…I’m just thinking
2 Likes
Whelp, take your room size…say 3x3. So 3x3 = 9sqft then 9sqft x 50watts/sq ft = 450watts needed then look at the actual wattage your light uses/rated for…other than that, you can use a par meter, watch the plants for wanting more/less light and/or a meter like PAR, Voltage etc
I personally run a 315 cmh (“new” style hps) in my 3x3’s…315watts/9sqft = 35watts per square foot ~2’ above the plants with much better growth and cooler than a 400w hid (hps, mh lamps) whereas, in my 2x3 (6sq ft) cabinets, I run 180w Quantum boards LED’s (60w each) for 30watts per sq ft and cooler than the cmh…to get the same 35watts per square foot in the smaller cabinets with the leds, I can max them out to 70watts each using a multimeter
7 Likes
If im to understand it correctly a 600 watts light over 4 plants is 100 watts
per plant
More like 150watts per plant… what size is your room?
2 Likes
i dont know why i wrote 100 I meant 150
1 Like
Just making sure we are on the same page 
1 Like
we are i was moving too fast
1 Like
If you want to be precise, just buy a light meter or PAR meter.
5 Likes
Only true way to know. Solid advice from @LemonadeJoe The PAR drop off towards the edge can be quite dramatic
2 Likes
Ya if u had 4 plants in a 2x3 space.
Theyd have to be snall plants
2 Likes