Good light source?

[The Codfather]

Dave your green house winter setup looks very good........do you should of done a thread showing pics of you setting it up for winter.......I would love to see more pics.....and may I maybe able to learn stuff from it......................is your fan on all the time ?

[MikeC]

Crikey, you guys really get into the detail of things. I just saw "daylight" on the box, thought 150w sounds quite bright, and £5 a bulb reasonable and bought them.

I try to limit all decision making to under 30 seconds now, otherwise nothing ever gets done.

[Vagetarian]

I try to limit all decision making to under 30 seconds now, otherwise nothing ever gets done.

I really need to take a leaf out of your book Mike

[Kristen]

Ahhhh, you made another reply

Sorry about that. But do stay on your toes

"I'm making the point that an 11W CFL produces very little light (less than a 60W incandescent no matter what the packaging says)"

Good point. The CFL's I am considering are 125W - 250W, so I wasn't considering lower than that, but you are right as posts I read on here are talking about "tick over" using very few Watts. (Which is my point too, if folk buy very low watts, wrong type of light spectrum, too far away from the plants, then I think they will be mostly wasting their money)

"The truth is that MH is very efficient and is very close to fluorescent (lumens per watt)"

I think (but don't have a source to hand) MH are actually more lumens-per-watt.

My MH is 400W, and covers about 2 sq.m. I have some smaller plants which are "stood" on up-turned pots to get them closer to the light, but they are all much further away from the lights than would be the case with Flours (indeed, if the MH light is within 2' of the leaves they will burn ).

It maybe efficient, but its also 400W which I calcualte as about 340 kWh to run 7 hours a day through the Winter. Forgotten what my Economy-7 is a unit - bit less than 10p I think? so about £30 per season, plus a new bulb every couple of seasons (they last much longer, but lose lighting efficiency)

"I believe it also has a better PAR rating because the colour spectrum is better suited for plants."

I'd not heard about PAR before. I've been swayed by the Marketing people of the Hydroponic's retailers (aiming at a different market of course!!) talking about Kelvin as a measure of light (suitable for plants). I'd appreciate any comments on that, as I've not seen PAR rating comparisons of LED / Fluro / MH et al.

Crikey, you guys really get into the detail of things. I just saw "daylight" on the box, thought 150w sounds quite bright, and £5 a bulb reasonable and bought them.

Daylight, 150W and £5 is brilliant. (this isn't 30W=150W I presume, but a real 150W bulb?)

But I'm a "detail person" I'm afraid ... that can be good, and can be bad ...

"I try to limit all decision making to under 30 seconds now, otherwise nothing ever gets done."

In my case it doesn't !!

[MikeC]

It's a 30W CFL, supposed equivalent to incandescent 150W in brightness. Looks very bright to me, one lights up my whole garage, certainly brighter in the garage than outside with all the grey clouds.

[Kristen]

I take back what I said about 30W = 150W ...

I expect CFL's are producing the same "Lumens" from 30W that an old fashion incandescent light was producing from 150W.

CFL Growing lights start at around 125W, which would be the sort of light power needed to get stuff actively growing in an artificial environment, and would probably do a couple of square feet.

so your 30W should be fine for ticking-over, but get it as close to the leaves as you can.

[Vagetarian]

Ah Kristen, you're talking about one of the horticultural CFLs that I was on about (envirolites).

I think these would be good to hang down in the middle of the room but if you intend to use it in a reflector go for straight tubes. If you think about the inverse square law and how light diminishes so quickly and then think about how the light gets thrown out in all different directions due to the shape of the lamp you will realise that only a very small amount of light directly hits the plant and most has to be reflected. This leads me to believe that straight tubes are more efficient than CFL tubes (in a light fitting).

I thought your MH was 250W but still, 400W of MH should be considerably better for plants than 400W of CFL.

I have seen figures quoted which puts MH above fluoro for LPW (lumen per watt). I think that because MH produces so much heat people assume they're woefully inefficient but it's not as simple as all that.

No doubt it's expensive to run! You can get a 250W halide however.

The PAR rating of a lamp is the only rating that is directly relevant to a plant. All the other ratings are related to what the human eye sees and our eyes are pretty crappe really. PAR is a total amount of light radiation that is available to plants for photosynthesis, across the usable spectrum.

The Kelvin rating is the overall colour of the lamp but it doesn't mean that the light produces only that colour. Our eyes are more tuned to certain colours than to others, plants are tuned totally different.

EDIT: Our eyes see the light as a result of adding together all the actual colours that the lamp produces (much like mixing paint colours). On the contrary, plants react to the individual wavelengths of the colours produced.

[Vagetarian]

Kristen, if you check the Telegraph web link that I put in a previous post you will see that no CFL produces as many lumens as the incandescent lamp it is supposed to be the equivalent of.

In terms of plants however, I think fluorescent is far superior because most incandescent light is wasted on plants (I think).

[Kristen]

Thanks. I looked at the Telegraph link. But they talk about Lumens (as published by the manufacture, which seemed to be about 20% less for CFLs) and Lux (measured by light meter as being about 40% less). Duno if Lux (as measured by the Telegraph) and Lumens are the same animal, or different means of measuring light.

Also, 2 years old, so technology may have moved on (although ... CFLs last SO long that if you bought the rubbish ones, when they first came out, that took 10 minutes to warm up you'd be stuck with that problem, and "perception of CFLs", for goodness knows how many years after that!!)

Either way, Lumens is the light perceived by the human eye (I think) so may not correlate to plant's-perception?

The heat from 400W MH is fine for me. I only use it in the Winter, so the "wasted heat energy" contributes to house-heating, and offsets other heating costs, albeit that Electric heating is probably the most costly type ... but "some claw-back"

Re: Fat-CFLs (horticultural type) and Tubes.

Interesting point you raise - and I don't know the answer. My perception is:

Fat-CFLs need a reflector. Thus some light travels to the reflector and back down to the plant which, given that CFLs need to be really close to the plant, must be wasting some of the light's energy. Particularly the really fat ones - 50% of the light must be travelling upwards, surely? and 50% into the core of the bulb cluster itself ...

The tube-rigs that I see have a bank of tubes a few CM apart. This is fine, but I think it works out expensive on fittings - 'coz you need a ballast and tube-fitting per tube.

I hung a single, bog-standard, 6' tube an inch or two above the vegetable seedlings in my windowsill propagator this spring. I've been using that windowsill propagator for 3 years or so, and I don't reckon the tube (running midnight-to-7am) made any difference at all. A more suitable Daylight, or Horticultural, tube might have been different though, and the newer T5 systems are supposed brighter than my old T8 type

OTOH my Tomato plants, brought into utility corridor from conservatory over night (as conservatory falls below 10C in early Spring) and put under my MH light during the night were noticeably more advanced that in previous years.



The "fat" and "very fat" !! CFLs (125W £15.00 and 250W £40.00)

Reflector to go with that are £25 each, although the one I have for my MH is only £15.00, and maybe good enough for CFL as well.



4 tube T5 Lightwave - 4 x 54W = 216W tubes £100.00. These are ideally suited to low plants - such as cuttings or seedlings, as you can get them really close to the plants. Dunno about for mixed-height things - like the over-wintering stuff we all have.

I think I'll ask on a dodgy-substances forum what they think the pros/cons of Fat-CFL vs. Flat-tubes/MH/other types are for their taller plants.

[The Codfather]

here are some usefull lighting reads and allthough alot are linked to fishtanks....they still there to grow things !

http://en.wikipedia.org/wiki/Aquarium_lighting

http://www.fishkeeping.co.uk/articles_2 ... uarium.htm

[Kristen]

Fascinating Coddy, thanks. Until now I never realised you might be into fish - Shows how slow I am ...

" Many aquarists will use metal halide bulbs in conjunction with either power compact fluorescents or T5 fluorescents since halide lighting does not have the overall balanced effect of other light types"

So basically we are a bunch of lightweights, we should be using MH, CFL and T5 fluorescents on our plants in order to keep up with the Fishy Jones !!

[Kristen]

It gets worse ...

" LED lamps of 3/4 to 2 watts can be implemented to come on at night, simulating the glow of the moon over the tank."

Moonlight? Heck! I gotta get myself some artificial Moonlight for my plants ASAP

[The Codfather]

The cheapest option would be T5

[Dave Brown]

Just re-read this. http://www.hardytropicals.co.uk/forum/v ... ilit=Light

[The Codfather]

its funny how thw same questions keeping coming up.......and it always comes back to the same answers.......whether it its lighting, cold, watering etc

as for lighting, as I have always said......T5 cheaper option.....metal halides dear option.....and in some case's and average light bulb......IMO