Lighting: T5 vs Metal Halide???

[StirCrazy]

Originally Posted by lorenz0

imo if your comparing a TEK or powermodual they are basically the same as MH. I did a par test comparing the 2 and they both put out similar numbers.

weird, I have never found a T5 that puts out anywhere near at 250 watt MH, but I am doing testing through water at a distance of 18".

and yes I have tested a Tek. problem is if you are testing a 10K MH then you need to have 10K bulbs only in the T5. actinic give a false high reading pn PAR meters.

Steve

[lorenz0]

Originally Posted by StirCrazy

weird, I have never found a T5 that puts out anywhere near at 250 watt MH, but I am doing testing through water at a distance of 18".

well the fact that in our house we have a strictly T5 tank and (during the tests) a 2x250watt MH set up. The t5's were slightly lower in par but comparable. Personally, i prefer the look of t5's. And imo, t5's bring out the color of sps. I could care less about growth in my tank as long as the color's produced are amazing.

but this isn't another t5 vs MH thread. let the OP say what they want for lighting

[lobsterboy]

i found that when using MH, i had deeper and shimmering colors on the corals.
with t5;s the corals have great color, but are more pastel, so it depends on what colors you are looking for.
myself i wouldnt mind trying the combo of t5s and MH, but for now i just have t5;s, and....THEY RULE THE DINOSAURS, YEAH!

[hslee]

*disclaimer - I've never tested numbers personally and am basing my entire post on the countless threads on this topic that I've read recently as I'm setting up my first SW setup... take what I say with a grain of salt*

It really does depend on preference - depending on what your particular needs are, one may be more suitable than the other.

MH definitely is better for depth, T5's for length (MH sort of has a spotlight effect, where as T5 spreads light more evenly). You can still get around this using T5's with good aquascaping and planning, if you place more light loving corals closer to the top.

As Myka said, for a deeper corner tank MH might be more appropriate just because of the shape of the tank.

I don't really buy into the cost savings idea with either fixture, since this'll depend on how often you actually change the bulbs (some change T5 bulbs every 6 months religiously, some let them go for over a year) and how many bulbs you decide to use (T5 fixtures go up to 8 bulbs, so changing them every 6 months makes it hard to have any savings)

As for power savings, yes T5 fixtures generally use less power, but this isn't a concern to everyone and I really don't know how noticeable of a difference it would be on your bill.

More choices in bulbs for T5 could be a blessing or a curse - there's a chance what you end up with after many different combinations (and $ out your pocket) could be the same or close to what you would've gotten with MH. With so many options, there's also the risk that you're running a combination that isn't ideal for your stock, and never knowing what you're missing out on.

As fkshiu said, it's hard to argue against using both, you can get the best of both worlds. If you weigh out pros/cons in your situation and decide you can't choose which one, choose both!

After all that... I could've summed it up with - either/or works, it's your choice and there are plenty of people happy on both sides

[loveless]

I am currently in the process of building a 330gal tank in wall. Atm I have a 180gal lit with 2x400w MH. and plan on using these same lights with better reflectors and light movers to light a 90x30 tank. If this works well enough then I am thinking on going to 250watt lights and seeing what those can do. This will give me MH lighting for less consumption than an LED setup, but not the initial cost of thousands of dollars. Will see if it works but this is and has been used for years in the hydroponic grow industry with great success.

[Myka]

Originally Posted by StirCrazy

weird, I have never found a T5 that puts out anywhere near at 250 watt MH, but I am doing testing through water at a distance of 18".

and yes I have tested a Tek. problem is if you are testing a 10K MH then you need to have 10K bulbs only in the T5. actinic give a false high reading pn PAR meters.

Steve

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?

[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.