watters vs lumens

[slim]

I have a 40 gal planted discus tank. I have 2 of the standard 36" fixtures that can support up to 40 watters each. All the 36" flourecents tubes I see are only 30 watters. I would like to find some 40 watter tubes so that I would have the recommended 2-watters per gal. Also, I see many of the lights market them self as being low-energy high-output, so I am wondering if I should be more concerned about the lumens then the watters. Any info would be great.

Also, of the 2-tubes I currently have. 1 is a blue spectrum (aqua-grow I believe) and the other is more of a white (flora grow I believe). What is better?

TGIF!

slim

[ChloroPhil]

Hey slim,

I'm still looking into the whole technical aspects of lighting, but I'll be happy to venture an answer for you.

If I've got my technical brain plugged in right a Lumen is the measure of a lights output. The higher the lumen rating the more intense output you're getting from that particular light.

A Watt is the measure of the power a particular light uses. The whole watt per gallon/liter rule of thumb applies as the higher watt bulbs tend to have higher lumen ratings.

[NickK]

Biotypical,
You are correct.

Nick

[slim]

Thus, lumens are the critical factor. Thanks for the tech support.

Also, any input on light spectrums would be appreciated. Blue vs White etc....

Gracias-
slim

[ChloroPhil]

Spectrum isn't as important as lumens/wattage. However, most people feel that the range between 5300 and 6700 *K gives the most pleasing look.

The lower in the *K spectrum a bulb is the yellower/redder it is. Conversely, the higher in the *K spectrum the bluer/whiter the light is. Some people find 10,000*K to give a pleasing look, though it's very white light.

To give you an idea of what I'm talking about, most reef tanks use 10,000*K lights.

[ronrca]

:thumbsup: Bio!

Just as a matter of interest, sunlight at noon is around 5000K! Therefore color spectrum should be around that value. K's too high or too low will not produce great plant growth.

[ChloroPhil]

ronrca,

I've got a pair of 13w PC fluorescents over my 5.5g and I think they're in the high 3000K-5000K range. They're much more yellow than my 6700K over the 90g. I find that it's a pleasing look in the small tank, but it comes across badly in photos.

[ronrca]

My lights are at 4300K I believe. Looks really nice giving the tank more of a shall I say 'natural' look perhaps similar to sunlight instead of white light.

[Ralph]

I need to learn more about lighting. Is there a good website that explains it?

None of my tubes tell what lumens are involved, is that because I buy cheap lighting?

[joelfish]

I've done some research on lighting in the past.

Your lightbulb won't have lumens listed on it. That's because at 2" from the bulb you get one reading and at 3 feet from the bulb you get another (lower) reading. Lumens is the measure of the amount of light that falls on a surface.

Flourescent tubes come in standard wattages by size. Your fixture may be able to technically support 40w, but the 40w tubes are 48".

I would not worry about 10,000k vs 5,000k. Most people use something in the 5,000k range for asthetics and price, but 10,000k creates a brighter look and grows plants like crazy if you match the nutrients to the higher light. I use 10,000K compact flourescents and I like the look.

If you want more light, look in to compact flourescents, or look into retrofitting your fixture with a electronic ballast.

Joel Fish

[joelfish]

Also, lower spectrum blues like in the actinic lights will promote compact, bushy growth while the higher red spectrums will produce longer, leggy growth.

I belong to an planted aquarium club in my town and we have used actinic lights on freshwater tanks to grow some neat looking plants. They also really highlight the blue in your fish ;).

Joel Fish

[joelfish]

The discus aren't hiding - they're just not there......

[Ralph]

Hi Joel,
Nice tank! It doesn't seem overly bright to me, though it's hard to tell from a photo.

I've never even heard of actinic lights, what are they?

[ChloroPhil]

Ralph,

Actinic lights are the really blue bulbs used primarily in Reef tanks. They're used to suppliment the blue spectrum found at depths a lot of our corals are found in.

Since plants aren't found at those depths actinic bulbs are an overdose of the blue spectrum. Plants need full spectrum or close to it more than any particular red/yellow/blue colors.

[ronrca]

You are on the right track Joel! However a small correction. Your definition of lumens is actually called lux (lux is the amount of light falling on a surface). Lumens is the amount of light that a source emits or could also be referred to as intenisty. You are correct though that at different distances you will get different lumens.

Lux is the ideal measurement for calculating light levels in planted tanks however unless you have a light meter, its nearly impossible (many calcs require and info about the light source). Lux is dependant on color/texture/reflection of the surface, distance from the light and so on.

Therefore it is not practical for lights to have rating of lux or lumens (although I have seen some energy saving fluorescents with lumen ratings). It is the easiest to use the watt per gallon guideline.

[Ralph]

You two are great.
Just to clarify though, is there a relationship between lumens and the light spectrum that the tube gives off? Also should I look for full spectrum lights or is there certain colors that are better for the plants and to make the fish look better? My background is from nonaquatic plants and there, each color range does different things for the plants.

[joelfish]

ronrca, Thanks for the correction. That's what I get for trying to recite this stuff from my feeble memory! :)

Ralph, I don't think that there's any direct relationship between lux/lumens and spectrum. However, the higher K ratings will look more white but actually contain more of the blue spectrum.

The reason that I don't like the watts/gal rule is that the cheapest flourescent in any given size uses the same watts as say a Coralife High Intensity 20,000K (not that you would use that for freshwater). Go ahead and do your own experiment and place both of these bulbs above your tank. The light from each doesn't even remotely resemble each other, yet watts is the same.

In our planted aquarium club, someone actually got ahold of a waterproof light meter. When we tried it out, we of course got quite different readings at different points in the tank. We weren't really sure what to do with that info, but it was interesting. It make sense that measuring the lux is the way to go, but so few aquarists do it that no one really talks in those terms.

I go for at least 5,000K lights, with good coverage, meaning multiple bulbs. I've found that this gives me the ability to grow a wider variety of plants and they do better. You can definitely use cheaper flourescents (these tend not to have a K rating), but the growth is slower.

In the end, we still must balance light, co2 and nutrients. Brighter light will dictate more co2 and more nutrients, otherwise, we're algae farmers!

thanks for letting me rant on this! :D
Joel Fish

[ronrca]

A very good question Ralph! One that I had not thought of so I asked our in house lighting expert.

The answer is yes! There is a direct relationship between lumens and color sprectrum. Why? In order to produce different k's, different phosphors are used. Different phosphors will use and give off different values therefore the lumens will be effected. This is what Joel is explaining in the regular tubes compared to high k tubes.

To get even more into detail, when talking about lumens, the output of a light, the wave lenghts of colors become an important factor. Red is one of the shortest wavelenghts, followed by yellow! Blue is the longest (This is why reefers use high k tubes). So, a higher k (more blue) will have a higher lumen output.

Finding the correct k factor for plants is rather difficult because there is no light source that can copy the sun. Full sprectrum lamps are not really 'full sprectrum'. What they do is add a little of red, yellow and blue plus some UV however looking at a color sprectrum graph, it is not the 'full sprectrum' (lumens will decrease compared to a high k tube). Unfortunately, thats the best one can do for now.

Plants do not use or need 'full sprectrum' though. There are only certain colors that plants actually use therefore why bother. The best one can do is provide the nesseccary lux levels. In the end, te k you choose is more preferance (appearance) than an actual substantial improvement in growth.

So far, I have been happy with using cool whites (I overdrive my fluorescents though using electronic ballasts to increase the output, same concept used in PC). In the past I have tried plant gro, full sprectrums, etc and was not impressed (plus the hole in my pocket they burned). Imo, I will not pay over $10 for a tube. I can not see that much of an improvement using more expensive tubes.

Im almost done! I agree with Joel. Mixing up the k is probably the best and would stay around the 5000K mark adding some 6500K and maybe 4000K tubes! Interestingly, the color of the plants is the color that the plants reflected and do not use (ie. green plants reflect green light therefore do not use green light).

PS - Joel, do you have those results from the light meter! I am interested in the results.

[Ralph]

Wow!
I'm going to have to reread this thread a couple times I think. It's a lot of info for a lighting novice.
It sounds like the general rules-of-thumb that I have been going by are actually valid and have scientific backup.
1) That regular fluorescent tubes are sufficient for most tanks (standard LFS plants and tank not too deep). The expensive alternatives (compacts,etc) are nice but not required for good plant growth (and may actually be too bright for discus).
2)Full spectrum may add to fish highlights but are not justified pricewise for good plant growth.
3) Mixing of tube types or brands is a good idea in that they are likely to compliment each other's shortcomings.

Are those correct conclusions?
Isn't the internet great, it has it's problems but being able to ask questions like this and get such knowledgeable answers in real time (and for free), it's great.
Thanks Joel, Phil, and Ronrca

[Smokey]

Just a side note: first- a very good insight into the need and type of lighting for an aquarium/plants/showing fish colours.
Second- my very expensive lighting engeeniering project consists of one (1) - 100 watt el-cheapo light bulb; mounted in a standard light vase, mounted (sitting) directly on top of the aquarium glass cover. Mind you; the front of the tank is facing (10 feet away) from a floor to ceiling picture window.

Just had to stand up and defend bare bottom- no plant tanks.

Smokey
(no green thumbs)

[ChloroPhil]

Ralph,

1. Yes, regular fluorescent lights are usually sufficient for plants if the tank isn't too high. I'm planning on using regular 48-72" shoplights from Home Depot for my rack room/nursery. The highest tank I'll be using will be 18". When you get into deeper tanks Power Compact fluorescents are better simply because they have the power to get sufficient light to the substrate.

2. Full Spectrum bulbs such as you can buy in the store aren't needed, true. However, neither are special spectrum bulbs. Thinking about it, the vast majority of the plants we keep aren't true aquatic, and spend a great deal of their lives above the surface or in very shallow water. Bulbs which have a good balance between the red, yellow, and blue spectrums are most useful as that's the kind of light these plants have evolved to use.

3. Many experts will say a bulb's a bulb. I mix *K ratings to get the look I enjoy the most but aside from that if a bulb is strong enough for my needs I don't really look at brand etc. Ironically, many of the bulbs marketed for aquarium use are the exact same thing as the bulbs you can find at your local hardware store or garden center, only they cost a lot more. :)

4. What really matters most, next to intensity, is the reflector. You can have a killer light fixture and a bulb to blind the sun, but if the reflector is poor you're going to lose a lot of light.

[ronrca]

On the right track guys, except for smokey who still seems to be in the dark! ;D

Im glad that there are more people that tend to agree rather than disagree. Most people strongly believe that full sprectrum, gro lights, etc are a must however by doing a little research, one will find out that this is not the case (open minded often helps too). What really urks me is that lfs prices. Not only will the tank/filter/substrate/heater/fish cost a lot, lighting will cost even more using PC plus 'special' tubes. What a better way to discourage new hobbiyests that can not drop thousands of dollars just to start.

Ralph's Conclusions: :thumbsup:

Like mentioned before, I use Home Depot cool whites that cost me $3-$4 each (I have 3' fixtures therefore slightly more than 4'). K value of 4100-4300K (Little low but I compensate by using the proper plants. I'm looking into finding some 6500K wholesale). I have 6 tubes so replacing them costs me $18-$24. Thats reasonable. Compare that to lfs tubes running $15-$25 (thats even low end tubes), total would be $90-$150. Ouch! I save $72-$126 every time Im replacing my tubes.

Which route do you want to take? I'll take the cheaper one and be able to spend more on discus and plants instead.

For more info, re-read Biotypical post again. :thumbsup:
I especially like point #3. How true and not only with lighting. Also, pumps, filters, ferts and most hardware/equipment.

;)

[Smokey]

Hey---RON--- I resemble that remark !!!!!! http://smilies.sofrayt.com/1/t/splat.gif...

[ronrca]

LOL! Sorry! :computer2: :wasntme: :scared:

[Ralph]

Smokey, we're going to sneak into your house tonight and put plants in all your tanks, with lots of gravel!

I want to see a picture of your tank with the lamp sitting on top. You did bring up a great point though, you reminded me of a tank I saw once that had sunlight coming into the front of the tank. The fish and the plants looked absolutely amazing. I saw colors in the fish that I didn't know existed. I think it had to do with the full spectrum of the sunlight along with the direction that it was coming from (it was reflected back off the fish at around 0 degrees). I couldn't set my tanks up like that because of logistics, but someday.....

Ron, Joel, and Phil, I'm going to sticky this thread so it stays up at the top of the section for awhile. Excellent information and a learning experience for me. Thanks

[slim]

Wow! I was out of town for work the last few days. It is great to see all of this valuable information. Much more than I am quite ready to digest. Though I am going to re-evaluate my lighting scheme, and make some adjustments. I need to look into the K value of my lights, and am going to try and be in the 5000 range. I think that will include getting rid of one of the blue lights I currently have. Thanks again. This site is amazing.

PS- I was gone for three days and I had an auto-feeder set. But mysteriously 2 of my rummynose have disappeared. I guess my Discus were hungry.

slim

[Smokey]

http://smilies.sofrayt.com/1/950/hides.gifhttp://smilies.sofrayt.com/1/g/bluegrab.gifI"ll be waiting for ya... lol

[joelfish]

ronrca,

I've been trying to get the light meter numbers you were asking about. It was a couple of years ago, so I don't think anyone saved them - but in talking to some folks about this, we all remembered that we were getting such varied readings all over the tank that it didn't seem that meaningful. If I were to have my hands on one again, I would just try it in an unplanted aquarium to get an idea of the effect of the water column and then go from there.

Do you have any pictures of your tank with the cool whites?

thanks,
Joel Fish

[ronrca]

My hypothesis for the 'weird' values are the tubes do not emit uniformly (meaning more phosphors in one area than other) and the water itself reflecting/refracting/dispersing the light. You remember any values like 200 or 600?

About my pics, you just click on the littlw world icon and you will be taken to my yahoo pics. I have not updated for quite some time but if you look at the most recent pics (pics close to the bottom), you kind of get on idea of the lighting!

[ChloroPhil]

*GASP*

Are those SILK plants? For Shame! :o ;D

[ronrca]

LOL!

When I first started my 90G (april), I went silkies! I could not afford plants at the time, neither did I have a clue (you mean there are underwater plants!!!)! That changed after 8 months (around Christmas) when someone in eastern Canada had a 90G full of plants for $60Cdn! Thats when it started! Boy am I glad I changed! :-\