|Today 01:10 PM|
As to 1) PAR meter accuracy.. I've stated and shown numerous times the "inaccuracies" of most meters..w/ the exception of a Li-Cor
2) Yes PAR measures (assume a li-cor for now) all light from about 400-700nm and treats each equally, which is not "exactly" correct based on the PUR idea...but it is relatively close..
IN general think of a progression from worse to better..
visual is worse than watts which lumens which is worse than lux which is worse than PAR which is worse than PUR which is worse than ind. measurements per species based on spectrum and quantum efficiency of a light......
any "economic" PAR meter has a terrible bias against light in the 660nm range and will under-sample it. It will also over-sample green and ect. each band having a corresponding inaccuracy..The 'hope" is w/ a full spectrum light that it averages out........ An "assumption"...........
Obviously "precision and accuracy are not at a "research" level.. and errors occur..
None should be taken as "scripture"...
Red line is approx how a Li-Cor measures light.....
As a side note T8's are marginally less efficient than a T5.. As to PC.. ???
I hear what you are saying in the fact that one shouldn't rely on any one measurement.. but one needs a starting point......
Even PUR is inaccurate based on an individual plant species..Since that "green line" is actually taken from an "average plant" response.. meaning an overall based on who knows what species..
speaking of PUR apparently there is one even better.......
good luck finding a PSR (or PUR) meter.. or a cheap way to measure it.......
Do we really need to go to that level??
|Today 06:43 AM|
I still don't think this PAR is correct... If this were true then having 1 T8 light or a Power compact light in a 25 inch tall tank apparently doesn't matter they both are low light... lol AIn fact this graph shows a PC light is almost identical to a single T8 light and that deff cant be true.. I've held a T8 6700 and a PC 6700 together and the PC is nearly double the brightness in the tank height tank. In fact I had 2 T8's and 2 T5NO over my 27g hexagon and replaced those 4 lights with 1 Power compact and my plants are still red and purple..
This is a Joke because I have some pretty strong reds and purples in some of my medium/high light plants using my Power Compact lighting.. And whats is AHS PC ?? What does the AHS stand for ?
This graph is basically saying the par from 1 T5HO is almost 50 at 25 inches and a PC light is like 2 or 3 par at 25 inches.. HAHAH ok lol... Has anyone actually measured a PC light with a reflector... these NO REFLECTOR graph are very biased... Why are you comparing individual T5HO reflectors with T8's and T5NO or PC light with no reflectors or white back grounds..
I haven't seen a T5NO use a white background.. The ones I've seen use reflectors, and my PC lights have reflectors on them... what company sells a PC light with no reflector. I've searched google for HOURS i cant find one person who has done measurments on PC lights with reflectors.. So until then that graph you posted above.. lol..
PAR is another FAD like watts per gallon.. It isn't accurate when measured in the proper 400-700nm range. PAR only measures the ACTIVE radiation output of a light... Not the usefull radiation PUR... That can be used.. so this is exactly another WPG fad that i wish would just go away.... You can have 2 6700k bulbs and 2 Plant grow bulbs.. those plant grows will outgrow those 6700k yet how can that be if the PAR is the same ? Because PAR isn't measuring the usefull lighting.. omg.. this is giving me a headache
Also your chart you post Jeffkrol and the ones posted on this sticky.. The measurements are WAYYYY off.. The ones he posted for T5HO's using like 15 different fixtures.. the average PAR at 25 inches for TWO bulbs is around 40-56 PAR And his chart for the PC lights.. using 1 36 or 55w BULB for 25 inches the par is 23.. So using a duel fixture for 2 bulbs the par is around 46. That's about the same as most of the T5HO light fixtures soo according to these charts a PC light near identical to a T5HO.. just depends on the reflector your T5HO has... Yet according to your chart PC bulbs are almost like T8's...
|11-21-2014 08:39 PM|
|drasan||Thanks for the help.|
|11-21-2014 07:42 PM|
|11-21-2014 06:28 PM|
|drasan||I appreciate all of your research & explanations - However, i have no clue what it all means. I asked my son who is currently in college & he had no idea either. Is there a simple way for a person of normal intelligence to figure out if 2 T8 aqueon 15 watt 18" bulbs are enough for a low light planted 55 gallon tank. The lights are in the original hood. Please help, I'm 53 and don't feel like going back to school. LOL Thanks|
|10-25-2014 03:25 PM|
|IiScaPeJuNkiEiI||About the par data for cfl lights in a dome fixture.. Is the measurement taken with a polished dome? Or a regular satin finished one? Need to know how the par is affected either way please. Thanks!|
|10-25-2014 09:27 AM|
|sprocketdiver||Ok try again so lights set for 7 hours continuous now 3 catfish and new plants.|
|10-24-2014 02:32 AM|
Thanks for the reply, some photos of the set up, I'm having trouble with algae and my plants not really taking off,
It's economic complete substrate and 1-2 bubbles co2 a second into an inline diffuser reactor
Baby tears all but dead now, watercress is spindly and very unhealthy, only the Brahmi is doing ok,
|10-21-2014 05:25 AM|
|10-20-2014 09:13 PM|
|sprocketdiver||Hi. I'm concerned I don't know what I'm dealing with. I have a 15 gallon. It's taller than wide. I have my light suspended from the ceiling. Not sure what distance to hang it though. Measured from the substrate. It's a 4 bulb t5ho fixture. But the reflector is funny. Advice. The reflector has loads of dimples all over it. It's not smooth.|
|07-06-2014 05:33 PM|
|07-06-2014 02:11 AM|
|rthomas529||How can a 26w cfl produce 50% of par as a 23w cfl?|
|06-17-2014 11:07 PM|
I'm planning on updating the light fixture on my parent's 30gallon tank to three clamp light CFL fixtures. Each fixture will have a 23w CFL in I think more than likely 8.5" diameter domes. Would this be sufficient as medium light for the tank? Thanks!
|06-10-2014 05:27 PM|
I have a new Apogee light meter now. It's pretty well corrected for the T5's for PAR and the curve. Has a few more options. Has other corrective %'s for other bulb types.
|06-10-2014 04:20 PM|
OK, thanks for the responses all!
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