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We can go 2 ways in regards to your question.

PAR could be used to the describe parabolic surface of the reflected light. I think A PAR38 bulb has a wider parabolic diameter (or thicker?) than a PAR 20. A wider bulb reflects more focused light.

PAR could also be used to describe the Photosynthetic Active Radiation which is the blueness and redness wavelengths of the visible light spectrum plants produce glucose for chloroplasts->growth, etc

Both are important for plants, but you also need to factor temperature, water, and CO2 for the overall health of a tank's flora & fauna.

Hope this helps
 

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Tank Lighting

Does "low PAR" by necessity mean "dimly lit?" If not, what is the solution?

Hello Sluggo...

Here's an alternative: With the right fixture and T8 or T12 bulbs from the local hardware store, usually no more than 8 to 12 dollars a piece, and they last a year or more, you can easily grow most aquatic plants on the market. You just do your plant & lighting research. With low tech bulbs, you can easily have 160 watts of 6500K light for your planted tank and not have to go through the "brain damage" of figuring PAR, Lumens, etc. You can use the old "watts per gallon" rule. Pretty simple.

Just a thought.

B
 

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BBradbury: You can't use the watts per gallon "rule" all the time. Why do you continue to repeat that misinformation? It only serves to confuse people who are new to the hobby.

A T8 bulb on a tank that's 18 inches deep may be low light. But on a tank that's 6 inches deep? That'd be overkill and would likely require pressurized CO2, EI dosing and such.

Sluggo: An easier route to take would be to tell us the tank you've got, its dimensions, the plants you keep or want to keep and the lighting you have or are considering. Many people on the forum can tell you if it's low, medium, high etc. Easier than determining PAR if your particular fixture isn't part of the PAR thread.
 

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Discussion Starter · #5 ·
Let me re-phrase: Is there a way to have a brightly-lit tank without the risk of creating an algae farm? I will be growing swords, c. wendtii, a. nana, pennywort, h. corymbosa in a 38-gal. I don't want it to be dim, but I want CO2 to be optional rather than mandatory. Can it be done?
 

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Yes Sluggo, this can be done very easy. I have a 38G and have been running it for two years now, without algea issues.
I purchased a dual bulb T5 High output, and ran both bulbs with a diy co2. That worked good and got my plant population up quick. But trimming became overwhelming so I removed the co2 and now only use one bulb @6500K for 9 hours a day.
Plant growth is still evident, but can go a month or two without having to trim.

I also allow salvinia to grow at the surface. This removes nitratres and regulates the amount of light in the tank.

Even thought I only use one of the two bulbs in the set, I glad I have it. Two bulbs are great to show off the tank when guests come, during photo shoots of the tank, and will be there in the future if I ever want to go high tech again.
 

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Discussion Starter · #7 ·
Yes Sluggo, this can be done very easy. I have a 38G and have been running it for two years now, without algea issues.
I purchased a dual bulb T5 High output, and ran both bulbs with a diy co2. That worked good and got my plant population up quick. But trimming became overwhelming so I removed the co2 and now only use one bulb @6500K for 9 hours a day.
Plant growth is still evident, but can go a month or two without having to trim.

I also allow salvinia to grow at the surface. This removes nitratres and regulates the amount of light in the tank.

Even thought I only use one of the two bulbs in the set, I glad I have it. Two bulbs are great to show off the tank when guests come, during photo shoots of the tank, and will be there in the future if I ever want to go high tech again.
I was going to go the T5 route, but couldn't sort out all the PAR data between 1 bulb, 2 bulb, and quality of reflectors. I went with the FugeRay because the PAR chart was straightforward. It looks a little dim to me, but I'm hoping that's because the tank is currently saltwater, and I am used to seeing the tank with the 192W PC fixture that is on there now.
 

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Watts per Gallon Rule

BBradbury: You can't use the watts per gallon "rule" all the time. Why do you continue to repeat that misinformation? It only serves to confuse people who are new to the hobby.

A T8 bulb on a tank that's 18 inches deep may be low light. But on a tank that's 6 inches deep? That'd be overkill and would likely require pressurized CO2, EI dosing and such.

Sluggo: An easier route to take would be to tell us the tank you've got, its dimensions, the plants you keep or want to keep and the lighting you have or are considering. Many people on the forum can tell you if it's low, medium, high etc. Easier than determining PAR if your particular fixture isn't part of the PAR thread.
Hello some...

The old "watts per gallon" rule has been a very helpful starting point for figuring basic lighting for my planted tanks, provided it's not used with high end lighting. I've used it for more than 10 years in my planted tanks of all sizes. I use the rule only with the T8 and T12 bulbs, but it works.

Just letting the newcomers know, you don't need a lot of knowledge of PARs, Lumens, etc. or buy expensive lighting to have a nicely planted tank. All you need are a couple of T8 or T12, 6500K bulbs to grow a long list of aquatic plants.

B
 

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BBradbury: Watts Per Gallon is only useful for tanks with standard dimensions and with old T8 bulbs. Unfortunately, it is not useful today for anyone who actually aquascapes or wants to know what light levels they've got.

Yes, you can grow all kinds of plants with T8 bulbs. But it's not a good idea to confuse people by giving them bad advice about Watts Per Gallon, which may or may not even apply.

Sluggo: I find my Finnex fixtures on freshwater seem much more bright than on salt. Primarily because there's less blue in the freshwater fixtures.
 

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Let me re-phrase: Is there a way to have a brightly-lit tank without the risk of creating an algae farm? I will be growing swords, c. wendtii, a. nana, pennywort, h. corymbosa in a 38-gal. I don't want it to be dim, but I want CO2 to be optional rather than mandatory. Can it be done?
That's a simple question. Here's the answer. More green light. The closer you get to 555nm the greater the apparent brightness. It known as photopic response
 

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Hello some...

The old "watts per gallon" rule has been a very helpful starting point for figuring basic lighting for my planted tanks, provided it's not used with high end lighting. I've used it for more than 10 years in my planted tanks of all sizes. I use the rule only with the T8 and T12 bulbs, but it works.

Just letting the newcomers know, you don't need a lot of knowledge of PARs, Lumens, etc. or buy expensive lighting to have a nicely planted tank. All you need are a couple of T8 or T12, 6500K bulbs to grow a long list of aquatic plants.

B
I think the watts/gallon bit causes more false confidence and problems then it solves. I did my first planted aquarium back in the mid 90's, and even then, the watts/gallon bit was coming under fire. Especially now that not only T-8 (which were not impossible to come by, but a lot more difficult for the DIYer a couple decades ago), but T-5, T-2, LED, as well as various configurations in regards to NO, HO, VHO, over/under driven, etc.

even within the realm of NO fluorescent tubes, T8 are more efficient than T12, and from what I've heard, T5 are more efficient than T8, and T2 are more efficient then T5. plus, a narrower tube diameter tends to make reflectors easier to build/more effective, etc.

All wattage measures is the amount of energy used. It only roughly correlates to PAR, which is what really matters in terms of what the plants need.

I don't even really like the watts/gallon rule for heaters, and there is much less variation amongst heaters then lighting methods.


Back to the original topic, I would think that any light sufficient to maintain a healthy planted tank would be more than adequate for observation. It may seem counter-intuitive, but I've found that a dark background and dark substrate seem to really help bring out the color (both plants and fish). Also, I generally like the aesthetics.

I'd be hesitant to just go adding a bunch of light in other spectra/wavelengths. I'm a bit out of my element here, but I wouldn't be surprised if some (not very well liked) variety of algae could make use of green light. But, yeah, human eyes tend to be pretty sensitive to green light, and it's also what plants are worst at using (why they look green- they absorb red/blue for photosynthesis, and reflect green, so we see plants as green (a bit over-simplified))
 

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Discussion Starter · #13 ·
Back to the original topic, I would think that any light sufficient to maintain a healthy planted tank would be more than adequate for observation. It may seem counter-intuitive, but I've found that a dark background and dark substrate seem to really help bring out the color (both plants and fish). Also, I generally like the aesthetics.
I'm hoping that once I upgrade my saltwater tank, my eyes will get used to the FugeRay on the 38, and it will look better when I am not comparing it to all that reef lighting. It's just that my initial impression was a little underwhelming. I will be using a dark substrate. Hopefully I am worried over nothing.
 
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