This thread is covering a lot of things these days? Most plants today are genetically grown and why farmers no longer uses pesticides. And why I am now seeing tree lizards, have multiple other lizards in my yard today which starting happening when my wifes family stopped spraying many years ago.
After 48 pages I don't remember seeing someone post they switched from MH to leds and their corals growth increased over what they saw using MH? If there is that person please post here. And please watt for watt Leds put out plenty of heat, they just use less watts, so less heat than a MH.
We were talking about a intentionally nondescript house plant as a parallel to describing coral density, not lizards outside or pest control from 50 years ago. You are within that eco-system and just a small part of it.
Growth would not increase with LED if you are using the same output wattage in the same fashion. (Easier said then done, nonetheless) The thread was not called "switched to LED and got more growth"?
Using heat for an LED is a straw man argument, they aren't nearly as hot as a MH. If hot MH is not a problem for you, why to you do want to believe LED are so hot?
The comment was made that LEDs don't have "heaters" in them like T5 and MH bulbs do, you are free to interpret the information and apply it as it suits you. I don't care what you use for your aquarium.
The lack of "heaters" is what gives LED a bit of an edge on efficiency.
All light is heat, so if you want to say LED produce more LIGHT/HEAT output per 1000watt, that would be accurate.
To get the same 1000w light output with T5 or MH, you are going to drawing say 1200 watts from the wall. That 200watt difference is pure heat and significant. It's wasted energy dissipated at the bulb, never converted to light most of it heating the room.
With a LED photons are released from electrons changing orbit around the nucleus of an atom. There is no heater, this is a fact not opinion.
Any heat generated at the diode is due to light being absorbed into the diode it's self, just as your car heats up when the sunlight hits the windows and gets converted to heat. Because all light is heat.
If you had theoretical perfect materials that had 100% reflection or 100% transparent lenses there wouldn't be any heat to speak of. Just like if you take the windows out of your car it would be cooler.
If touch the diffuser surface of a XR-15 LED running @ 50watt it's very warm, some would say uncomfortably hot.
I wouldn't recommend touching a the lens on a 50MH bulb as that would result in a burn.
With T5 bulbs the heaters are less intense and spread out on both ends of as many bulbs as you have in your fixture. That is why 1000w of T5 is a friendlier fixture then 1000W of MH. IMO. (The heaters in T5 directly effect PAR output which is why ATI cools their fixtures)
In the context of the thread, "would i MH it again?" Yes.
I've just replaced a MH for LED on a small tank, not because I didn't like the MH, the MH was too much wattage, I just needed less light for that particular tank. Led is nicer to work with and install.
If I was building a large system of tanks that needed affordable and easy lighting I would be using MH. You can't buy 1000watt of LED for $250 You can't buy 1000w of T5 for $250 either, just the bulbs would cost more.
I would probably use as big of bulbs as possible, assuming that one large heater in the 1000w is better then 4 separate heaters in 4 250w lights. (I'm speculating on that, though the inefficiency of 4 ballasts would probably be worse then one large ballast) Sure it's going to make a bit of heat, electric heat is expensive but being in Canada it's not actually "wasted" for most of the year. So the answer is yes, I would use MH again and whole heartily recommend it. I certainly wouldn't want to purchase 10,000w of LED fixtures, ouch. I would consider building them though if I can source the bare diode panels that had appropriate reef colors. Even still I'm sure the MH is still the most practical choice.
On a small tank LED. On a medium size tank LED/T5 hybrid. On a large tank T5/LED possibly MH with LED. LED gets to at least play a role in all scenarios because we like to that narrow band florescence that makes coral pop. When used with another light source it is not doing the heavy lifting, just a visual thing.
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