Lighting - getting a bigger tank

[AlexT]

Over the next month, I will be upgrading from a Juwel Primo 110L (17.7 inches high) to a Juwel Rio 180L (19.7" high).

My question is about the light unit that comes with the new tank.

Current 110 L tank: x2 tubes (LED) both are 6500K (pretty decent K rating for plants?)

New 180 L tank: x2 tubes (LED), one is 9000K and one is 6500K giving an average of 7750K (too high K rating?)
- But what I could do is either of two options
(a) Replace the 9000K with another 6500K giving an average of 6500K obviously
(b) Replace the 9000K with a 4425K giving an average of 5463K

Thoughts?
Plants are simple ones really (Elodea densa, Vallis, Willow Moss, Amazon Frogbit, Crinum thaianum), no additional CO2, using TNC Lite liquid fertliser and the tank will be fairly heavily stocked fish wise. Water is pH 7.2, KH 4, GH 6, Temp 75F

Current set-up below, I want as fully planted and thriving planted as possible please (with the above plants in mind).

 

[Byron]

My comments are directed solely at the spectrum. I do not know anything about the light units, intensity, etc.

Kelvin is a useful means of assessing spectrum, as is CRI (colour rendering index). K is more common. Plants need light that is high in the red and blue as these two colours drive photosynthesis; red is more important of the two. Adding green to the mix does improve plant response, even though it is not needed to photosynthesize. It is likely because this mix is closest to the sun under which plants evolved. And green light is needed for green plants because the leaf colour is due to that light being reflected. So red and blue allow the plant to grow, and green provides the light necessary for colour. A Kelvin in the 5000K to 6500K range is best here, according to numerous scientific studies (many are cited in Diana Walstad's Ecology of the Planted Aquarium).

Light high in the blue, producing anything above 6500K, is more likely to cause problem algae. Blue light penetrates water better than any other colour, which is why marine corals use and need blue light--and many aquarium light units seem to be intended for marine tanks. Not so with freshwater plant tanks, Years ago I had a dual 4-foot T8 light over my 90g and one tube was 6500K and the second was 9,000K. I had algae increase, and the plants did not really do that well. I replaced the 9000K with a 5000K, along with the 6500K, and plants improved without algae issues.

Red leaf plants reflect red light, and this is why they do not do as well without very intense lighting that has sufficient red. You're not dealing with that, but it is worth keeping in mind should you decide to acquire any red plants. Red is primary for photosynthesis, and when it is getting reflected you need even more of it.

BTW, you cannot average the Kelvin by combining two different lights. The 6500K will help the plants, but the 9000K is all wasted as it is blue and the plants cannot use it out of balance, if that makes sense, so algae does. The 6500K is fine; another 6500K is better than the 9000K, unless you can get a lower K like a 5000K to go with the 6500K. The lower the K the "warmer" the white light, with more red and less blue, while the higher the K the reverse, "cool" white with more blue and less red.

 

[Byron]

Edit, just saw the 4425K option, that with a 6500K would probably be ideal.

 

[AlexT]

BTW, you cannot average the Kelvin by combining two different lights. The 6500K will help the plants, but the 9000K is all wasted as it is blue and the plants cannot use it out of balance, if that makes sense, so algae does. The 6500K is fine; another 6500K is better than the 9000K, unless you can get a lower K like a 5000K to go with the 6500K.

Thanks Byron,
I think I'll go for option (b) then of my original post, what do you think?
(b) Replace the 9000K with a 4425K giving an average of 5463K

Obviously forget the "averages"
or to reframe the question; what's more ideal? x2 6500K tubes or x1 6500K Tube and x1 4425K tube?

Thanks again

 

[AlexT]

Edit, just saw the 4425K option, that with a 6500K would probably be ideal.

you beat me to it, see above

 

[Byron]

Thanks Byron,
I think I'll go for option (b) then of my original post, what do you think?
(b) Replace the 9000K with a 4425K giving an average of 5463K

Obviously forget the "averages"
or to reframe the question; what's more ideal? x2 6500K tubes or x1 6500K Tube and x1 4425K tube?

Thanks again

I found the warm (4425K) and daylight (6500K) a very good match both for colour rendition and plant response/growth. Having said that, I do not know this particular unit, and LED can be different. But I would think this mix better.

 

[AlexT]

I found the warm (4425K) and daylight (6500K) a very good match both for colour rendition and plant response/growth. Having said that, I do not know this particular unit, and LED can be different. But I would think this mix better.

Thanks, that's great, because I find x2 6500K a bit plain, but I wanted a nice planted tank so can't have it all, but I think the 6500 with a 4475 will hit the spot more for me.

 

[AlexT]

Current tank; 110 L, 17.7 inches high, x2 LED total wattage 21
Upgraded tank; 180 L, 19.7 inches high, x2 LED total wattage 38

Having established what a good / ideal Kelvin rating would be, should I be concerned about LED wattage for my upgraded tank in light of my plants? To remind you of the plants and set up;

- Elodea densa, Vallis, Willow Moss, Amazon Frogbit, Crinum thaianum
- No additional CO2, using TNC Lite liquid fertliser
- Fairly heavily stocked fish wise.
- pH 7.2, KH 4, GH 6, Temp 75F

 

[Byron]

Current tank; 110 L, 17.7 inches high, x2 LED total wattage 21
Upgraded tank; 180 L, 19.7 inches high, x2 LED total wattage 38

Having established what a good / ideal Kelvin rating would be, should I be concerned about LED wattage for my upgraded tank in light of my plants? To remind you of the plants and set up;

- Elodea densa, Vallis, Willow Moss, Amazon Frogbit, Crinum thaianum
- No additional CO2, using TNC Lite liquid fertliser
- Fairly heavily stocked fish wise.
- pH 7.2, KH 4, GH 6, Temp 75F

This is difficult to answer because I have no idea how intense this light is. This was for me a huge problem when looking for LED (which I never managed to sort out, another story). Ever since the 1980's I used T8 fluorescent tubes, and the wattage was standard for the length of the tube, so it was consistent, but only for the same type of tube. Wattage is only the amount of energy a tube or LED uses, and it can vary a lot between different tubes/units. Even the T8 tubes became more energy efficient, so in the latter decade a 4-foot T8 6500K was 32 watts, whereas previously it was 40 watts. And, the 32w was/is actually more intense light than the 40w was, because of improvements in manufacturer to save energy.

If other members are familiar with this light, they may be able to provide information.

My thinking though was always to provide less light rather than more, because of the significant impact light has on fish. My tanks were covered in floating plants to further reduce the light. I tried many different plants over the years, and those that worked and thrived I kept, and those that clearly had insufficient light I tossed out and forgot about. In my case, with what I considered moderate light intensity, but some thought it more low light, I had real success with Echinodorus sword plants (the green leaf species, not the red) and Helanthium pygmy chain swords, and crypts did very well until they screwed up my water anyway, and moss and Java Fern and Anubias did well. Floaters obviously did well, being under the light and with their aerial advantage, and I had beautiful red tiger lotus with huge floating leaves that were vurgundy coloured. Stem plants really didn't have enough light, so I forgot them.

Photos below are of the 5-foot 115g Amazon riverscape and the 70g 4-foot Amazon streamscape.

 

[AlexT]

This is difficult to answer because I have no idea how intense this light is. This was for me a huge problem when looking for LED (which I never managed to sort out, another story). Ever since the 1980's I used T8 fluorescent tubes, and the wattage was standard for the length of the tube, so it was consistent, but only for the same type of tube. Wattage is only the amount of energy a tube or LED uses, and it can vary a lot between different tubes/units. Even the T8 tubes became more energy efficient, so in the latter decade a 4-foot T8 6500K was 32 watts, whereas previously it was 40 watts. And, the 32w was/is actually more intense light than the 40w was, because of improvements in manufacturer to save energy.

If other members are familiar with this light, they may be able to provide information.

My thinking though was always to provide less light rather than more, because of the significant impact light has on fish. My tanks were covered in floating plants to further reduce the light. I tried many different plants over the years, and those that worked and thrived I kept, and those that clearly had insufficient light I tossed out and forgot about. In my case, with what I considered moderate light intensity, but some thought it more low light, I had real success with Echinodorus sword plants (the green leaf species, not the red) and Helanthium pygmy chain swords, and crypts did very well until they screwed up my water anyway, and moss and Java Fern and Anubias did well. Floaters obviously did well, being under the light and with their aerial advantage, and I had beautiful red tiger lotus with huge floating leaves that were vurgundy coloured. Stem plants really didn't have enough light, so I forgot them.

Photos below are of the 5-foot 115g Amazon riverscape and the 70g 4-foot Amazon streamscape.

Thanks Byron, I meant to come back to this thread, because I wasn't sure if I might be beating a dead horse with all these specifics for a low tech set up, and wasting people's time.

Obviously, Kelvin is important, because due to shady marketing, someone can easily come away with 9000K or higher marketed as "make your plants flourish".

But you have reminded here of something so very basic that I often forget. It can be trial and error, and that can be part of the fun, and part of the frustration, and you've also reminded me about the fish's needs. As you know, I have a lot of small tetra's. I'm lucky in one regards, as Crinum thaianum is my "go-to" plant and if you've seen any of my latest videos, it doubles up as a floating plant. Those lovely thick leaves straddling the surface.

 

[Uberhoust]

Kelvin is a useful means of assessing spectrum, as is CRI (colour rendering index). K is more common.

Summary (TLDR):

• CRI - How natural the light looks (For you)
• Color Temperature (K) - Frequency distribution of the light (For the plants)
• PAR - How much plant usable light is produced (For the plants)

To clarify these two values are not measuring the same thing and have no equivalencies. With LEDs you kind of need both and then some. The CRI effectively states how well the light matches the light temperature curve (K), over the whole spectrum, but does not imply what the color temperature is.

- CRI measures how well the light replicates all the colors you would have for natural light but at different color temperatures
- Color temperature (K) is a measure of the light spectrum distribution with low temperatures generating more red light and higher temperatures generating more blue light.

You could have a light with a High CRI and but a Low color temperature (K), which would not be good for an aquarium (warm light LEDs). And you could have a light with low CRI and high color temperature (Burple LED lights red and blue only).

For any light, what we are looking for is a light that has frequencies that are useful to the plants, history suggests that for aquariums that is light around 6000k, using the color temperature. If we wanted a near exact match to a 6000k light source with an LED light we need also need one with a high CRI index, otherwise the light might be missing some frequencies necessary for proper photosynthesis. Note that the main chlorophylls mostly use light in the red and blue sides of the spectrum, but accessory pigments use a full selection of light frequencies, and these pigments are necessary to help support photosynthesis.

With the advent of LEDs, and the increase in useful phosphors and florescent materials used in the LEDs the proper frequency distribution of the light being produced is a bit more difficult. Now an LED light could be tuned to a specific plant's requirements. These requirements do not necessary fit the color temperature-based frequency distributions. Additionally, the color temperature and CRI do nothing to determine how much light to use. To address the issue of quality and quantity of light, the PAR rating is starting to be used for some aquarium lights. PAR is a measure of the Photosynthetic Active Radiation. The par rating for a light describes, coarsely, how much radiation that the plant can use that is emitted from the light.

Overall, none of these measurements work well as an individual way of determining the quality and quantity of the light you need for your plants, primarily because many manufacturers of lights can throw up a bunch of numbers that makes their product look good but don't really convey any true meaningful information, they will skip the values that they don't want you to see. Your best bet is to use a higher quality light with high CRI and appropriate color temperature rating, but also has an appropriate PAR rating for your aquarium setup. Most of the good lights now provide the possible CRI, the Color Temperature, and the PAR rating (this does get a bit more complex with adjustable lights). There is still a lot of ambiguity so other people's experience's with their lights is still important.

I personally target CRI of 90 or better, 6000k, with 90 to 140 PAR at 12" from the light. CRI higher means the light looks more natural (important to me), the 6000k means the light is focused on the needs of the plants, and the PAR ensures I have the right amount of light. As far as my plants are concerned my best light is a cheap LED 6500 k, with a low CRI (<70), but higher PAR (120), but I cannot stand the lack of reds and greens with the bluish cast.

 

[AlexT]

Summary (TLDR):

• CRI - How natural the light looks (For you)
• Color Temperature (K) - Frequency distribution of the light (For the plants)
• PAR - How much plant usable light is produced (For the plants)

To clarify these two values are not measuring the same thing and have no equivalencies. With LEDs you kind of need both and then some. The CRI effectively states how well the light matches the light temperature curve (K), over the whole spectrum, but does not imply what the color temperature is.

- CRI measures how well the light replicates all the colors you would have for natural light but at different color temperatures
- Color temperature (K) is a measure of the light spectrum distribution with low temperatures generating more red light and higher temperatures generating more blue light.

You could have a light with a High CRI and but a Low color temperature (K), which would not be good for an aquarium (warm light LEDs). And you could have a light with low CRI and high color temperature (Burple LED lights red and blue only).

For any light, what we are looking for is a light that has frequencies that are useful to the plants, history suggests that for aquariums that is light around 6000k, using the color temperature. If we wanted a near exact match to a 6000k light source with an LED light we need also need one with a high CRI index, otherwise the light might be missing some frequencies necessary for proper photosynthesis. Note that the main chlorophylls mostly use light in the red and blue sides of the spectrum, but accessory pigments use a full selection of light frequencies, and these pigments are necessary to help support photosynthesis.

With the advent of LEDs, and the increase in useful phosphors and florescent materials used in the LEDs the proper frequency distribution of the light being produced is a bit more difficult. Now an LED light could be tuned to a specific plant's requirements. These requirements do not necessary fit the color temperature-based frequency distributions. Additionally, the color temperature and CRI do nothing to determine how much light to use. To address the issue of quality and quantity of light, the PAR rating is starting to be used for some aquarium lights. PAR is a measure of the Photosynthetic Active Radiation. The par rating for a light describes, coarsely, how much radiation that the plant can use that is emitted from the light.

Overall, none of these measurements work well as an individual way of determining the quality and quantity of the light you need for your plants, primarily because many manufacturers of lights can throw up a bunch of numbers that makes their product look good but don't really convey any true meaningful information, they will skip the values that they don't want you to see. Your best bet is to use a higher quality light with high CRI and appropriate color temperature rating, but also has an appropriate PAR rating for your aquarium setup. Most of the good lights now provide the possible CRI, the Color Temperature, and the PAR rating (this does get a bit more complex with adjustable lights). There is still a lot of ambiguity so other people's experience's with their lights is still important.

I personally target CRI of 90 or better, 6000k, with 90 to 140 PAR at 12" from the light. CRI higher means the light looks more natural (important to me), the 6000k means the light is focused on the needs of the plants, and the PAR ensures I have the right amount of light. As far as my plants are concerned my best light is a cheap LED 6500 k, with a low CRI (<70), but higher PAR (120), but I cannot stand the lack of reds and greens with the bluish cast.

Really interesting, thanks for explaining. My tank is a Juwel Rio and I am not sure if Juwel give out that extra information, will take a look, thanks again!

 

[Uberhoust]

As far as the Juwel Rio goes that is a pretty common tank in Europe, you might actually get better info by asking about the lights in those tanks from other members of the group. There are some good lights that only have one or two of the items listed, simply because they haven't either officially tested them or it hasn't made its way into their marketing documents. Fluval lights don't give all the details either but I have heard from others that they are pretty good.

 

[Uberhoust]

No par rating for the Jewel lights but the "Nature" tube of LEDs is at about 6800k, https://www.juwel-aquarium.de/websi...RE_Product_Information_Sheet_EU_2019_2015.pdf. The other bulb might be a warmer light.

 

[Uberhoust]

From my perspective they seem to be a pretty reasonable configuration unless you are an expert and know exactly what you want.