Lighting: T5 vs Metal Halide???

[StirCrazy]

Originally Posted by Myka

You make some very good points. When you take away all the variables, and actually compare them on fair grounds T5s just won't keep up to MH - especially when you get a bit of depth to the water.

Why do actinics give a false high reading on PAR meters?

PAR meters are calabrated for either sun light or electric light, and at a base spectrum. the longer wave lenght of the blue light in an actinic bulb is way out of perportion for either calabration as they are done based on 5500K(if I remember corectly). so when it recives a higher level of actinic than the calabration set had it thinks it is more powerfull and reads acordingly. the same holds true for say 3000k, it will report less PAR than there actualy is.

they pick the middle for the calabration and then it is only out a bit on the ends so you get a happy medium. I think at 400nm mine is 2.7% higher than actual ouput. so it isn't a lot, some meters are scewed by as much as 10%.

this is why I don't like to compare different colors of lights with out a disclamer, for an example, my AB 10K 250watt SE driven by a M80 ballast and my special home made reflector, would put about 550 to 600 units of PAR on the bottom of my 24" deep tank, so that is through 22" of water and 7" of air (I don't run the water 2" below the top, only 1 but my sensor is 1" tall also) for a total distance of 29" A tek unit with a 10K bulb load (4 bulbs) placed directly on the top of the tank for a distance of 24" from the sensor (22"water 2" air) got a max reading of 295 units of PAR. Still a respectable amount of light. now as for the disclamer, a 10K ab is actualy 12600ishK so a bit more actinic than the 10K T5s. so lets use the 10% which is the worst I have heard of and take that off my ABs it would still come to 495 to 540 Units, but seeing as there is only a 2000K difference in the bulbs I would guess it would be a lot close to the actual reading, as it takes some good actinic, as in 20K bulbs or pure actinic bulbs to get the meter to over estamate.

Steve

[Myka]

Thanks for the explanation Steve!! =]

[Dolf]

Wow- I was going to ask for a reference link as I don't like to just be told that basically actinic produce a false reading without knowing why. I always like sources- but in this case that explanation was good enough that I could easily quote it as a source. Thanks for the post.

[TheMikey]

That makes a lot of sense. I was doing some PAR readings on my tank last night and was getting about 680 PAR on the bottom of my 15G (about 16" from bottom of light to bottom of tank) with a 4x24W T5 setup. I'm using 1 x 15K, 2 x 22K (all aquascience), and a stock Actinic. I thought that was WAY too high.

Regardless, though, all I really care about is if my SPS has nice polyp extention (and they do!) and good colour.

[StirCrazy]

Originally Posted by TheMikey

That makes a lot of sense. I was doing some PAR readings on my tank last night and was getting about 680 PAR on the bottom of my 15G (about 16" from bottom of light to bottom of tank) with a 4x24W T5 setup. I'm using 1 x 15K, 2 x 22K (all aquascience), and a stock Actinic. I thought that was WAY too high.

Regardless, though, all I really care about is if my SPS has nice polyp extention (and they do!) and good colour.

yup and like I have stated in other posts, I now believe that given the right water flow and water quality you can grow SPS under a 60 watt bulb, but the growth will be slow and the color not the greatest.

when I first started out I had 10K PC's and overdriven NO actinics, and I grew SPS, they were close to the top, and only had ok color and slow growth. I added a 175 watt 10K bulb and I got sa little more color and a little more growth. then I changed out the NO actinics for VHO actinics, a little lore of each again. so I decided to take the plung. got two 250 watt AB bulbs for a steal (1 month use on them) found a source for two advance M80 ballasts, bought a full sheet of spectral aluminum and made reflectors and or sold 1/2 the board at that time material to make there own, and I came up with a nice design that pumped out the light.

with this set up I couldn't add Kalk fast enough so I added fans for more evaporation, and kicked the Ca reactor into high gear.

from testing T5's I found out they put out about 1.5X the light that a same lenght PC does (a lot better than I expected) and a PC puts out about 10% more light than a VHO of the same lenght and color, unless you running and IceCap ballast on your VHO then it is way less but thats another story)

I do believe there is good use for T5's. I use them on my FW planted tank and am very happy, if heat is a concern then ys use them, but I think the cost is prohibitive personaly

just to put out my thoughs, lets pick a 48" sunlight supply 8 bulb unit. so the fixture is 494.00 and bulbs are 25-35 so we'll say an average of 30 each X 8 = 240. so for 1 year you need 480 worth of bulbs for a total of 970.00 for the first year of operation.

If we go MH we can get a 48" sunlight supply Maristar metal halide fixture which come with the two 250 watt MH HQI bulbs and two T5 actinic bulbs for 814. sence the T5's are only being used for color suplementation I would run them at least a year and from testing my MH bulbs over a few years I can say I have no problem running them for 16 to 18 months, but I will say for the pourpose of this compararason 12 months.

so initial year the MH is 150ish cheaper., now ongoing bulb replacment every year for the T5 will be 480.00ish and the MH will be 260.00 using 100 buck MH bulbs. power consumption wise, just in bulb rating the MH will use 612 Watts plus about 3% for the power factor of the ballast so say 494ish watts.

The t5 will run 440ish with the power factor. so for power savings it is not as much as people think.

anyways it is supper time..

Later

Steve

[Canadian]

I'll go on record stating that I think MH is the best simple option for reef aquarium lighting.

With that said, I'll play devil's advocate and post a link where the exact opposite consensus about this topic was reached elsewhere:

http://reefcentral.com/forums/showth...readid=1609217

Every time this topic is discussed the recommendations become so dogmatic and obstinate it's painful (and I mean from both camps).

[Canadian]

Originally Posted by StirCrazy

PAR meters are calabrated for either sun light or electric light, and at a base spectrum. the longer wave lenght of the blue light in an actinic bulb is way out of perportion for either calabration as they are done based on 5500K(if I remember corectly). so when it recives a higher level of actinic than the calabration set had it thinks it is more powerfull and reads acordingly. the same holds true for say 3000k, it will report less PAR than there actualy is.

they pick the middle for the calabration and then it is only out a bit on the ends so you get a happy medium. I think at 400nm mine is 2.7% higher than actual ouput. so it isn't a lot, some meters are scewed by as much as 10%.

this is why I don't like to compare different colors of lights with out a disclamer, for an example, my AB 10K 250watt SE driven by a M80 ballast and my special home made reflector, would put about 550 to 600 units of PAR on the bottom of my 24" deep tank, so that is through 22" of water and 7" of air (I don't run the water 2" below the top, only 1 but my sensor is 1" tall also) for a total distance of 29" A tek unit with a 10K bulb load (4 bulbs) placed directly on the top of the tank for a distance of 24" from the sensor (22"water 2" air) got a max reading of 295 units of PAR. Still a respectable amount of light. now as for the disclamer, a 10K ab is actualy 12600ishK so a bit more actinic than the 10K T5s. so lets use the 10% which is the worst I have heard of and take that off my ABs it would still come to 495 to 540 Units, but seeing as there is only a 2000K difference in the bulbs I would guess it would be a lot close to the actual reading, as it takes some good actinic, as in 20K bulbs or pure actinic bulbs to get the meter to over estamate.

Steve

If that was the case wouldn't you expect an actinic T5 lamp to produce greater PAR values than a "whiter" lamp - given that you're suggesting 420nm wavelength is some how misinterpreted as being more "powerful"?

Here are measured PAR values for various T5 lamps:

http://tfivetesting.googlepages.com/par

[Canadian]

Steve,

Can you please explain how actinics produce "false high" PAR readings despite the fact that measured PAR values for actinic T5HO lamps are considerably lower than whiter lights?

For example:

ATI
Sun Pro 357
Aquablue 336
Blue Plus 311
Actinic 137

How does that actinic lamp running at 137 PAR some how artificially create "false high" PAR readings when the measured PAR is less than other lamps surrounding it?

[StirCrazy]

Originally Posted by Canadian

Steve,

Can you please explain how actinics produce "false high" PAR readings despite the fact that measured PAR values for actinic T5HO lamps are considerably lower than whiter lights?

For example:

ATI
Sun Pro 357
Aquablue 336
Blue Plus 311
Actinic 137

How does that actinic lamp running at 137 PAR some how artificially create "false high" PAR readings when the measured PAR is less than other lamps surrounding it?

dimmer bulb, who knows how they are made. anyways I am trying to get my house painted so I can sell it so I don't have time to explain it again.. Go to APogee's site they tell you what there corection factors are and such. wanna buy a house?

Steve

[StirCrazy]

Ok, re read my stuff, between painting rooms.. I made a mistake, yes I know.. imigian that, not that it happens a lot but yes even I can make a mistake.

the meters do not over estamate actinic, the under estimate actinic and overestimate the higher end. in a rounded out bulb this will all work out in the pudding (6500K ish) but in a actinic bulb it will give you a lower reeding than you should have and in a 3000K bulb it will give you a higher reeding than you should have.

reasons are due to the spectral responce of the meters to the wave lengths, and to get a unit that reeds good all over you need to spend over 1000.00 bucks.

anyways sorry if there was any confusion Mr Canadian.

Steve