The results are in

[StirCrazy]

Well I went to Safari's today and took some PAR measurments on various lighting setups. The PC and T5's had pretty much brand new bulbs and the MH were well used bulbs. Sence I could not rearange the lighting setups on the tanks in the store the MH readings were taken over a greater distance which means that they would have had an even higher output if all the distances were equal.

the first was a 55watt PC, at a distance of 6.5" from the meter (1.5" air 5" water) its reading was 139 units of PAR (rounded up to next whole number).

the next was a HO T5 running two 24 watt bulbs, at a distance of 6.5" from the meter (1.5" air 5" water) (same size as PC unit) it's reading was 216 units of PAR (rounded up to next whole number).

then a 250 watt mogal set up at a distance of 12.5" from the meter (7.5" air 5" water) with old bulbs, its reading was 363 units of PAR (rounded up to next whole number).

and finaly was a 250 watt hqi combo fixture which was a distance of 11.5 (6.5" air, 5" water) it had a reading of 524 units of PAR rounded down to whole number.

so what does this tell us, when chosing between VHO/PC and T5, the T5's are the way to go, as it gives you 64% more PAR output

but if you want the higher intensity and punch, you still want to use MH as your main lights and suplement for color with T5's.

So there it is in black and white, T5's are and exelent upgrade for vho and PC tanks but a down grade for MH tanks.



On a Side note I did buy a T5 unit for my fresh water tank today sence I wanted to pugrade from the T8 setup I was using. as well as 3 bags of florite, but thats another thread.

Steve

[Doug]

So why not measure the T-5 par on 4ft. 54w bulbs, instead of the smallest they make?

[Jason McK]

What are you measureing with?

Just worndering the actual instrument as I might be interested in getting one

j


BTW: Doug great to finally put a face to the name

[Samw]

What were the color temps of the PC and T5 bulbs? Could make a big difference.

[StirCrazy]

Originally Posted by Doug

So why not measure the T-5 par on 4ft. 54w bulbs, instead of the smallest they make?

cuz thats the sizes they had set up in the store, and with floressent bulbs the wattage is a function of length so the intensity at any point along the bulb should be the same no matter what the length is. the difference is in the area they cover.

Steve

[StirCrazy]

Originally Posted by Jason McK

What are you measureing with?

Just worndering the actual instrument as I might be interested in getting one

j


BTW: Doug great to finally put a face to the name

It is a PAR sensor from apogee.

Steve

[fkshiu]

Originally Posted by Doug

So why not measure the T-5 par on 4ft. 54w bulbs, instead of the smallest they make?

That's a very valid point. A fair comparison would be to compare 48" 54w T5-HOs with 250W MH. Or 24-36" T5-HOs with 150-175W MH.

Why? The majority of people who use 250MH setups have 4-ft+ tanks. The vast majority of tanks of shorter lengths do not have the depth requiring 250W MH (let's just say more than 20"). Shallower tanks running MH are mostly 150W.

Secondly, nobody who is also considering MH runs just 2 T5-HO bulbs. Teks, Aquactinics etc all use a minimum of four T5-HO bulbs for their units. In fact, someone with a 48" long tank wanting to keep SPS/clams is in the market for for a 6x54w T5-HO system.

This is not even counting the variables of reflectors/bulbs/ballasts that can greatly affect PAR readings.

So in other words it should be a fair fight. For example, testing high-end versus high-end systems that an experienced reefer wanting a crisp white look would consider purchasing for his/her display tank:

An fan-cooled 6x54W T5-HO system using individual Icecap SLR reflectors and a 660 ballast with 4 German aqua-blue and 2 UVL actinic bulbs

versus

2x250w MH on M80 HQI ballasts, SLS lumenmax pendants and SE 14K Aquaconnect bulbs.

(Oh, and the measurements should be taken underwater as well).

[StirCrazy]

Originally Posted by Samw

What were the color temps of the PC and T5 bulbs? Could make a big difference.

they were both 10000K bulbs, the T5 was a dual bulb fixture but that won't affect the intensity.

the MH were 14K bulbs (didn't have any 10K for me to try, but they would have been a higher reading if they were 10K.

Steve

[skylord]

Correct me if I'm wrong but it wouldn't matter if your testing 2 3 or 4ft bulbs against the MH. Your not reading the par for the entire tank, just the area below the bulb.

Wouldn't testing an area between the two MH bulbs show something quite different for par? It wont change with the T5 over the length of the fixture.

My concern for a test like this is color temp and reflectors.

Scott

[StirCrazy]

Originally Posted by skylord

Correct me if I'm wrong but it wouldn't matter if your testing 2 3 or 4ft bulbs against the MH. Your not reading the par for the entire tank, just the area below the bulb.

Wouldn't testing an area between the two MH bulbs show something quite different for par? It wont change with the T5 over the length of the fixture.

My concern for a test like this is color temp and reflectors.

Scott

yup your right, although we did find the DE250 MH did have an increadably large area of full intensity.

but heres the thing, a MH will effectivly light a 2ftX2ft area (just to pick a size). in this area you will have a center of about 1ftX1ft (At a specific depth) that will be brighter than the other area but only slightly and the dimmer area (if you can call it dimmer) will still have more intensity than a T5 output.

the main think to look at is on deeper tanks, as you go deaper the socalled hot spot of a MH increases in size so you get a wider coverage that is even. where I do think the T5's would be perfect for is shallower coral tanks with lower light types (I am not saying you can grow high light corals under them as we have seen them grow under a NO bulb befor) or I think they would be a very smart purchase for a FOWLR where you just want the color to make the fish pop as it would be even everywhere. I am not claiming that MH is a nice even lighting, but rather people seam to think if you are not right under the bulb there is no output, where in reality you can't be more wrong about that. My old tank (1/2 of a 180) hade over 350 units of par in the corner on the bottom (24" +6" of air and offset 4" behind the bulb and 12" to the side) with the lighting I had then, the T5's didn't make that directly under the bulb at 6.5"

Steve