Lighting Wattage Question

[Adamc1303]

I currently run MH & T5's. My setup is 2 x 400 W Mogul MH and 6 x 39W t5's. All together thats 1,034 watts of lighting. I see on my apex that the MH pull about 368W of power. Is it accurate to use 1,034 watts as the amount of power the fixture draws when comparing to other setups? Meaning if I were to go with a 10 x 80W T5 fixture would it be 1,034 Vs. 800 watts or is it more complicated then that? I ask because I do see that the MH pull less power when I look at my apex and I would think that volts and other factors effect this as well.


Thanks,

Adam

[Ron Reefman]

I'm no electrical expert, but I think it's going to depend on the power supply/ballast/driver and the bulbs. They are all a bit different so exact numbers should be taken with a grain of salt.

And lighting wattage is good info if you are concerned with electricity usage. But if you are using it to compare how much light is being delivered to the water, it's a VERY old school approach and almost useless when comparing between MH to t5 or leds. They are all very different.

You can get a much better comparison by getting PAR readings. Light photons are light photons whether they are produced by MH, t5 or leds and that's what a PAR meter counts.

[Adamc1303]

Thanks! I am more concerned with energy consumption.

[Ron Reefman]

Glad to hear it. Good luck.

[jda]

There is overhead on each ballast or driver. Factor in 10% for magnetic ballasts a rough estimate, IME Electronic are usually more at spec, but still have overhead of a bit and usually put less power to the bulb. LED and T5 power supplies, drivers and ballasts have overhead too. There is a +/- threshold that any electronic device can operate at - lights are no different, so 368W is probably in range, especially if on electronic ballasts.

I think that it is reasonable to expect a 10x80w to have 10% ballast overhead and fans and run at about 880-900W. If you are thinking about saving electricity, then look at HQI (DE) or 20K Radiums (SE) on M80 ballasts. They spec out a bit less than 280W with the overhead and usually output more than a 400W MH. They are also so good looking that you don't really need T5 anymore except for dusk/dawn in which case you could have half as many. You could reuse your current reflectors and canopy/hood/fixture too. I use a pair of HQI over my 4' tank, have par around 750 par at the top and 450 par at the bottom, can grow high light SPS anywhere in the tank - 560 watts on/off with a light timer and I change the 14K phoenix bulbs every two years for $55 each. 20K Radium would be the same wattage, but the bulbs only last a year. I don't care about dusk/dawn since the coral do not care, so I use no other lights.

A Kill-A-Watt does not lie. They are inexpensive if you want to double check your apex.

PAR can be OK, but it will only measure in the visible range from about 430 to about 650 (they list 410 to 655, but then the graphs show very little detection under about 430 or over 650) nm - the sensor is hobby grade and not all-encompassing, but is probably quite excellent for the price point. The new meters go down to 380ish but the output is skewed a bit below 400-410 - I don't think that most folks have many of these yet. Both the T5 and MH light source will output light below and above this that most coral will use - more below than above, but still more. A best of breed MH light like a 20K radium and 14K phoenix will put out nearly half again as much output below a PAR sensor limit that it does in the range, so they are underestimated by a LOT. Even most modern LEDs (the multi-colored ones with more than blue/white) will output a bit below a PAR sensor bottom limit, but not nearly to the extent of T5 or MH. If you use Super Actinic VHO, it is more like 3/4 below the PAR meter reading. However, output in the range should still be steady if you want to use it as rough guide. PAR meter is kinda like horsepower - fun to talk and post about, but torque is where it is at... but you need an integrated sphere to get torque of a light which and tens of thousands of dollars and not a few hundred bucks. ...so not really all that easy to get torque on a reef light so nobody still knows how much light is getting to a tank, only that light sources with high output below 420-440 are severely underrated. There is a guy who posted some numbers from an integrated sphere a while back.

[Adamc1303]

Thanks! I am running 400W SE Radiums but not on the M80 ballasts. I'm using galaxy ballasts which I believe are electronic.

[mcgyvr]

Watts = Volts x Amps

Apex measures at the source of the power (upstream of ballasts)..
Stated/List wattage is supposed to be "worst case" of the operating ranges..