jason

Sorry but i would have to not agree with t5 having the same output as metal halides,,the t5 bulbs have a much lower PAR than the metal halides bulbs do,,metal halides emmit a much more intense and brighter light spectrum than t5 bulbs do,,,I just know alot about this subject due to having saltwater coral tanks for almost 21 years now..and as we all know saltwater people always know their crap when it comes to lights!! Take care-Jason. and the metal halides really dont per say tapper off that much their kelvin changes over time with the age of the bulb,,so lets say you bought a 6500 kelvin bulb and burnt it for one year ,,after that one year that kelvin drops,,and the light emmits more of the red spectrum,,so it could be like 4700-5200 kelvin now that its been used for so long,,after about 9 months I notice the bulbs spectrum is alot different than when i first had the bulb when new,,plus I always know when to change the bulbs cause i start getting in my tank alot of undesirable algae!!

JCDerrick

A lot of the Fluorescent lighting I've seen causes plants to stretch. My halides don't cause any reaching/stretching for the light and they lights are 4-6' above the plants - a lot of them. I still think Halides, while expensive, are the best way to keep plants alive and happy indoors. I would only use Fluorescent if I had another light source to supplement the fixture.

In layman's terms, and correct me if I'm wrong:
The K value is how close the light is to natural sunlight. I think 6000K is close to normal sunlight (judging by the chart on the previous page). So it's like the quality of the light.

I think the Wattage and PAR sort of go hand in hand. Wattage is like the "power" of the light. The output of the light is always a good deal less than what it actually uses to run the light.

The PAR value is the "fuel" of the light; at least in terms of being a plant. Like food.

Again, this page is good at explaining it in detail:
PAR Watts, Spectral Distribution & Kelvin Temp.

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Malama 'Aina



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jason

[quote=JCDerrick;57413]A lot of the Fluorescent lighting I've seen causes plants to stretch. My halides don't cause any reaching/stretching for the light and they lights are 4-6' above the plants - a lot of them. I still think Halides, while expensive, are the best way to keep plants alive and happy indoors. I would only use Fluorescent if I had another light source to supplement the fixture.

In layman's terms, and correct me if I'm wrong:
The K value is how close the light is to natural sunlight. I think 6000K is close to normal sunlight (judging by the chart on the previous page). So it's like the quality of the light.

I think the Wattage and PAR sort of go hand in hand. Wattage is like the "power" of the light. The output of the light is always a good deal less than what it actually uses to run the light.

The PAR value is the "fuel" of the light; at least in terms of being a plant. Like food.


The higher the CRI is of the bulb the closer it is to the suns natural spectrum Cri stands for color rendering index with 100 percent being the sun and the K stands for kevin ,,like a bulb that says 2100 wich would be like you normal srew in incandescent bulbs that you put in your home fixtures the higher the number in kelvin the more blue spectrum a bulb emmits and the suns kelvin rating in summer is in the 5500-6400 kelvin depending on air polution cloudy day..... certain things in the air will filter out but not completley degrees of kelvin their for changing the kelvin out put of the sun.. and what are eyes perceive as bright enough light for plants,,plants see alot different than we do,,so for instants your eyes see that the light in your house is bright enough for you plants ,when infact your plants are seeing it as being in heavy shade,,lights and lighting are sometimes very confusing..

Chironex

I bought the 6500k compact fluorescent bulbs from the guy on eBay for $12.98 apiece. Works well enough for me.

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JFK

Switchable ballasts are a great option too if you decide to go the HID route. You can switch between metal halide and high pressure sodium with the flick of a switch and a different bulb. For keeping you plants happy and green, a halide cannot be beaten by anything. If they are large and start to fruit, you would be better off switching to high pressure sodium as the different spectrum promotes fruiting far better than a halide. Sodium lamps also give off more lumens per watt. I have a switchable 400 watt, and when I change from halide to sodium bulbs the light instantly becomes more intense.

Also, I read someone mention having a sheild with halides....this is very important to have, but they only shatter if they are splashed with water.