T5HO does not degrade as much as we thought?
This is quite an interesting page I found on the subject of lighting very high ceilings but the interesting point is way down on the page.
It suggests that unlike all other fluorescents T5HO uses a 'programmed start' electronic ballast and will only degrade (lumenwise 5-6%) over its lifetime!!!
The others are on 'instant start' electronic ballasts or magnetic 'flicker' ballasts which as we know do reduce lifetime.
It also suggests that MH lights degrade a lot quicker too!!!
Any thoughts? Please note we are talking T5HO here and not T5.
White Paper - Fluorescent Vs. Metal Halide in Hi-Low Bay Applications
Very good article, and it highlights, by omission, why our T5HO lights are so much more efficient than T8 lights - the reflectors. It looks like most of the gain in efficiency is not from the bulb itself, but from the great individual reflectors collecting and directing more of the light to the tank. Also, I wasn't aware of the operating temperature advantage of T5HO. An all around better bulb for our use.
Interesting article. I've become a big fan of T5HO over the last 2 years.
I was just thinking on another vain to do with lighting. Why does a Nano tank need more 'WPG' than an average tank?
Yes it is smaller in surface area but does this mean anything?
For example if a 7USG Nano is 10" deep then surely it can use the same WPG as a standard 20-40USG tank that is 12-14" deep.
Wouldn't the closer proximity to the light yield higher PAR and therefore negate the argument of lesser surface area?
No, simply measure the cheap crappy tiny bulbs.
That, not so much the watt/gal rule, it the issue.
Folks think all bulbs are the same.
A well made 96W PC or a 54W T5 will put out a lot more PAR per watt than say a smaller cheapo PC/T5.
the other issue is the ends where the electrodes are is much closer, that's where you have the poorest performance.
Take a look at a neon sign or any FL bulb, T5 etc.
Measure there and the then measure the center(block off the other hlaf so you do not measure 1+1 ends, and only measure one end).
It's about 1/2 as much.
That + cheap little junk bulbs, which are for the most part, all that nano folks have available, poor reflectors as well etc, it more likely why. Note, these are all things I have and anyone can measure with a PAR meter.
The ADA relationship likely has to do with some of this plus their fixtures look nice but have low output(seems to be on purpose to out think folks, or a vestiage from old days, it worked them, they did not need to re work and make something new, why bother?)
I would not mind going to ADA and measuring all those lights on multiple tanks.
As well as a CO2 meter.
Bet there's a very very strong correlation between
The light intensity at the substrate is roughly proportional to one over the square of the distance up to the bulbs/reflector. That is the most significant geometric factor in light intensity in the tank. The watts per inch of bulb length is about the same for all T5 bulbs, or T5HO bulbs, or T8 bulbs, etc. So a tank that has a full length fluorescent bulb over it will have half the watts when it is half the length, etc. So, the length of the tank is a factor in how much total light is over the tank. (As Tom pointed out, about 2-4 inches of fluorescent bulbs produces no light or very little light, so as the bulb gets shorter, the length available to produce light is drops faster than the length drops. A 4 inch long bulb would produce almost no light.)
Originally Posted by SuperColey1
But the depth, the front to back dimension of the tank, has nothing to do with the intensity of light at the substrate, other than that the front and back glass do reflect some light to the substrate - around 15-20% max, in my 10 gallon tank. This means the light intensity at the substrate cannot be a function of tank volume - two otherwise identical tanks with one tank twice the depth will have the same intensity, but the bigger one will have half the watts per gallon. The bigger tank will also, of course, have much less uniformity of intensity over the entire substrate.
The only reason watts per gallon has been reasonably useful is because most tanks have about the same geometric proportions, but once you deviate from that geometric shape, watts per gallon mean absolutely nothing. And, as soon as you use short fluorescent tubes, like on nano tanks, watts per gallon means nothing for fluorescent bulbs.
Last edited by VaughnH; 02-15-2009 at 06:12 PM.
Assuming I had a 13" long tank and a 30" long tank both the same depth and height. I then use the same light which was longer than both tanks with a screen at the ends of the tank to only use the proportion directly over each of the tanks so 30" of the tube over the 30" long tank and 13" of the tube over the 13" long tank.
Would this mean the same light intensity at the substrate of both?
Not trying to say the above is wrong at all. I am trying to get my head straight on the statements of needing higher light on Nano tanks.
Is it just the factor of the smaller tubes or much more of a mathematical quandry?
Yes, both would have the same intensity. But, the 13 inch long tank would only have 13/30 of the wattage of light over it, and 13/30 of the tank volume, so, the same watts per gallon.
Originally Posted by SuperColey1
The more interesting question to me is if the two tanks are the same except that one is 13 depth (front to back) and the other is 26 inches depth (front to back). If you could somehow get the light spread out over the 26 inch tank to get reasonably even intensity from front to back, without losing intensity in the middle, both of those would have the same intensity too.
Clearly these are just rough estimates, not precise calculations, but I'm betting they are close to being correct. So, the question about which light to use on a given tank is really more about tank depth and length, and not at all about tank volume.
I measured my 13 W Pc lights vs the 55 W PC's.
I measured a measly 60 micromol at 12" for the 13w
I measured 180 micromol for the 55w.
If I added the 13 w on a nano tank, say 3 gallons = 4.3 w/gal
For the 55w, on a 20 gallon tank = 2.75 w/gal
Which has more PAR along the bottom?
Even though the distance was about 10" farther for the 55 watt bulb..............and the w/gal ratio was much lower................
Those larger ratio of length to ends reduce the amount of light and the cheap made mass produced junky little bulbs stink. Just use a PAR meter instead of using W/gal ratios for nano's, they are really not any different, you just waste more electric.
I hate nanos anyway, PITA to keep water levels the same, things evaporate rapidly Cheap, easy to set up, stock etc, can have many replicated etc.
The 13 watt bulb on a 3 gallon cube tank should give about 30 micromols (9" deep tank). The 55 watt bulb on a 20 tall tank should give about 90 micromols, less if you raise it enough to get more nearly even light distribution at the ends of the tank.
If you put the 55 watt bulb over the 3 gallon nano you should get about 9/18 x 55 watts over the tank, or 28 watts, and about (12/9)^2 times 180 or 320 micromols. (Same intensity per inch, but higher because it would be closer to the substrate.) And, it would look so nice, with the overhanging bulb at both ends!