Replacing current HPS with quadruple power in LED

efficacy impacts the watts per squre foot yu want.. or square whatever unit of measure doesn't matter. 4sq feet.. metric is actually easier for this.. so this is roughly 0.4m^2 for easier math (0.3716122blahblah) photoperiods (this is relative to 12hours per day due to fewer ours than vege) you want at least 500-900 in 1m^2 as baseline over 12 hours. Min 0.4 * 500 PPFD for 12 hours/day = 200umol/s Max 0.4*900 PPFD for 12 hours/day = 360umol/s So, you want a light putting out roughly 400umol/s relative to .4m^2. If you regulate co2 and elevate ppms to 1200ish, you can go another 25-33% higher on maximum PPFD. as is, 900 is likely slightly over what ambient co2 levels. this is safer to err on high side -- simply raise light a couple inches or dim it slightly. Take those same numbers and multiply by .67 to see wht is needed for "Autoflowers" and an 18/6 cycle... 133-220umol/s from light. less light per second, but more hours of it being on and it is all the same. This is all directly proportional to hours per day of use... so during vege period (or an autoflower) with 18/6 cycle.. .you have 6 more hours.. that's 150% more time, so you need proportionally less umol/s of photons over that period of time to provide same amount of energy to plant. you can use 66% of above values over 18 hours vs 12. (12 vs 18 12/18 = .67)... reciprical for going other direction... you my be familiar with the line "you need 150% more light in flower phase" .. this is what it is derived from... hours of use. the plant can metabolize roughly the same amount per 24 hours relative to CO2, temperature and RH%. fixing all other facors makes it easy to undertand any one's influence. it doesn't matter if over 12 hours or 20... the plant will only metabolie so much per 24 hours... there is a ceiling.. it is mostly related to CO2 levels. CO2 provides the carbon (major building block.. a "backbone" to most things produced). umol/s of photons provide the ATP (energy) to power cellular growth. A cheap light, i'd go closer to 40watts/sq ft... A no-name brand off amazon? 50watts/sq ft high efficacy lighting you can go down to 30watts/sq foot and achieve the above suggestions. These lights cost more upfront, but often save you money over time of ownership in electricity costs as well as longevity of the diodes.... run them hotter/hrder and they never reach that advertised "50,000" hours of use... high efficacy lights WILL last as long as a good driver has warrantied. Check out the FC-XXXX (xxxx= 4-digit number) The spec sheets are accurate and the diode count backs it up. Some ugly math for most any light with samsun lm301 diodes: Take watts divided by total number of diodes... entry- 0.50watts per diode -- these will be 10-20% less efficient than the high end stuff. Probably won't see anything exceeding 2.5umol/J efficacy (a directly proportional to electrical use unit of measure) mids: 0.375 watts per diode -- You get a good bump in efficacy at this wattage per diode. You will get many more houors of use with this seemingly small decrease in watts per diode. Still well short of diminishing returns. With highet bin diodes, you can* reach the 2.8-2.9umol/J range, but more often you will not be gettting top bin diodes, so a ~2.5-2.7umol/J ceiling is more likely. High: 0.25 watts per diode -- You won't see much go lower than this... well into diminishing returns and doubling diode count will ony add cost with little return. This is also what the actual Samsun specsheet for these diodes are measured and weighed for the specs. These specs are often shown for lights driving their diodes twice as hard (0.5w/diode range)... With these lights, even with lower bin diodes you re getting 2.8-2.9umol/J efficacy. top bin and no uv or ir diodes? you are >3.0umol/J and tht is the current ceiling given existing technology. so, use that to avoid bogus marketing claims.. the math is easy.. the concepts you can be familiar with in a short period of time. e.g. you see anything advertising >3.0umol/J (or when you divide umol/s by watts/s it equate to a larger value), then you know it's bullshit. other diodes like UV, red, far red are often less efficient than your base samsun white diodes. the samsun white diodes will be about 95% or total. so, if they have more bells and whistles, expect a small difference lower than if 100% samsung white diodes. the "CCT" impact efficacy... the samsun specsheet uses the 5000k as it's default diode.. tables show data on the various color temps available and bin of diode they produce of each etc... BUT, the ceiling of 220lm/w or 3.10umol/J (same damn thing in this context) is more efficient than warmer CCTs. e.g. often see 3000k diodes mixed with 5000k diode on lights... tht basically makes any value of > 3umol/J bullshit and impossible. some average algebra skills will help you avoid a dud product... my suggestion.. spend a bit more now... a more efficient light also puts out proportionally less heat (the umol/J unit does this too as well as proportional for electric bill costs). get 7-10 years out of teh highe end stuff... your driver is likely to go bad before the diode do i that context. dimming happens regardless... however, it happens much much faster when diodes are driven with greater watts/diode. also costs more watts per photon produced... A true cost of ownership can be calculated with this provided info. A high end light you only need ~120-150watts to cover a 2x2 and then some. 120w *2.8umol/J = 336umol/s -- that's a tad under the 360 above.. oops.. but you can see how it is calculated. target of 360umol/s / 2.8umol/J = 129 watts minimum with a light approucing 0.25watts per diode and bulk being samsung lm301 diodes.. ** your area was <0.4m^2, so that 120 may actually be up near ceiling too... these are all ballpark figures relating to photosnythesis and the science behind it all... the units are precise, of course.. but min/max values for umol/s of photons are ballpark ideas. better to err on high side and dim or raise light if needed. "Max" is a good idea to hit as you do lose some intensity over 3-5-7-10 years of use and depending on how many watts per diode they are operating at. If you have a little more than needed, you can ameliorate any dimming over that time. Samsung specsheet lists 50k or 60k hours before 90% of original intensity, if run near 0.25watts per diode. hotter they are, faster they dim. a dedicated bloom light only uses 4380hours/year if run every single day... that's a 10 year bloom light, potentially, and never dipping below 90% of original intensity.. if you have 10-12% more, you can completely ameliorate any dmming tht occurs and maintain the same coverage and intensity as day one. never a problem to overshoot a small bit.