Light Bulbs To Chew On

[waterdrop]

Now that lljdma06 has sent you guys out to pasture in the PARC and Dave has got the plants doing the cycling for you I thought it only fitting that I, as "beginner who talks too much" should attempt to pose another truly difficult question to draw the experts out of retirement and probably cause a huge sigh with nothing penned...

So here goes: I've read umpteen million articles on having light that's shining down at this or that energy, focused better with this or that reflector and kept on for this or that many hours, adjusted in this or that way to balance plant growth with algae avoidance, but its not good enough, I hunger for more!

What is the nature of the light problem in freshwater planted tanks? I know we all struggle with our own trial and error on this question but... How does the successful planted tankmaster *think* about his/her light? Which tradeoffs are more important than others? I'm just hoping to encourage you to share your insights, things that surprised you perhaps.. but I'll try to start that off by somehow shaping a few of my simple-minded questions.

What got me really thinking about light this time was realizing I'd gone over a year without changing out my fluorescents for new tubes. Lots of posts saying to do this. But then I thought, ok, they're dimming a tiny bit (not that I can see but the time is supposed to do that to them) but... and here is The Question... What is the difference, to plants, between more brightness (more photons per minute I'd guess/say) (in whatever wavelengths, lets leave that out) vs. more or less hours per day?

I found myself thinking about these 3 things, the tube somehow being different from age, the "energy" (for lack of a better term, since none of the light measurment things seem to work out as a useful scale) and the hours. I just can't get this out of my head, wondering about the brighter, fresher new fluorescent bulb vs the older dimmer one.

The hours have some interesting tidbits people mention. There's a statement people make that any photoperiod less than 4 hours won't be "seen" by the plant. That sounds interesting and I've even repeated it to others but I don't pretend to really understand that, any help? There are older statements by Dave and others here I respect who discuss starting out new tanks at maybe only 4 hours and then gradually increasing hours, watching for algae. I'm always interested in hearing peoples thoughts on that. There seem to be lots of people that will just declare that you need at least 9, 10, 11, 12 hours of light for healthy plants.. but that seems to cry out for more discussion.

WD

 

[lljdma06]

Oh boy. Here we go.

I will be completely honest, I do not think much about these matters and I am not especially innovative. While I used to be regular about changing bulbs, now, not so much. I think I have one on its second year. I've had tanks with 12hour photo periods and ones with 5-6hour ones. I have had tanks with a lot of light and now, ones with quite a bit less. I think it depends on the individual situation.

Sorry I don't have much else to contribute at this time. I just do not dwell on these things like others do. I just like keeping planted tanks. You are great to ask these questions, though, it forces people to take a moment and think about what they are doing.

It will be interesting to see others put their two cents worth.

llj

 

[waterdrop]

Don't hold your breath. I went into this figuring it might take a month before Dave and Aaron notice it, so I'll have to be innovative, making up reasons to bump it back up, lol. WD

 

[Dave Spencer]

What is the nature of the light problem in freshwater planted tanks?

The problem is quite simply people thinking that high light is needed, something I was once guilty of. I could still run an algae free tank with no problems using 108W of T5 over 30 USG, but that was because I understood the principle of making other nutrients non limiting. Too many people have too much light and not enough of something else downstream, in the form of carbon (the main culprit), N, P, K or traces.

Provided there is “enough” light, concentrating on ferts will become apparently more important. In truth, plants such as HC benefit more from good ferts, and CO2 in particular, more than from high light.

I know we all struggle with our own trial and error on this question but... How does the successful planted tankmaster *think* about his/her light? Which tradeoffs are more important than others?

There is no trade off. I can use two T8 tubes the length of my tank which will cater for any plant out there. It is that simple.

What got me really thinking about light this time was realizing I'd gone over a year without changing out my fluorescents for new tubes. Lots of posts saying to do this.

Change the tubes when they no longer work. Once a year is something constantly dredged up from the past, with no basis in modern plant keeping circles.

But then I thought, ok, they're dimming a tiny bit (not that I can see but the time is supposed to do that to them) but... and here is The Question... What is the difference, to plants, between more brightness (more photons per minute I'd guess/say) (in whatever wavelengths, lets leave that out) vs. more or less hours per day?

The only two factors regarding light that we need concern ourselves when it comes to plants are intensity and duration. As far as intensity is concerned, most of us are unable to measure PAR, but this isn`t a problem if you run two T8s, as there is enough light available, provided your tank isn`t ridiculously deep. Those who think Amano runs high light tanks are in for a surprise, as the PAR levels in his tanks are low level lighting at the substrate. Tom Barr is the person that has done a fair bit of measuring PAR in planted tanks.

As for duration, I go for eight hours maximum. Personally, I don`t see any real benefit going longer than an eight hour photoperiod. Plus it saves my electricity bill, and I use less ferts and CO2.

Kelvin, Lumens blah blah blah really don`t matter. I was recently banned from a low tech planted tank forum (US based), for daring to question the site guru who insisted that tubes need to be 6500K for plants to grow. My argument was that since when has the light from the Sun always been 6500K when it reaches the plant? Clouds, shadows, depth of water, turbidity, aspect of the Sun and so on…..all affect the spectrum being received at the plant. I am sorely tempted to run a planted tank under marine lighting to prove a point, but I just couldn`t bear the look of a blue tank at the moment.

Plants adapt to the light available to them above their minimum light thresh hold.

I believe that the intensity of light will cause more problems for people, rather than duration, within reason. It is the higher growth rates under more intense light that are going to find out the tanks with poor CO2, rather than slower growth due to lower light, but longer photoperiod tanks.

The hours have some interesting tidbits people mention. There's a statement people make that any photoperiod less than 4 hours won't be "seen" by the plant. That sounds interesting and I've even repeated it to others but I don't pretend to really understand that, any help? There are older statements by Dave and others here I respect who discuss starting out new tanks at maybe only 4 hours and then gradually increasing hours, watching for algae. I'm always interested in hearing peoples thoughts on that. There seem to be lots of people that will just declare that you need at least 9, 10, 11, 12 hours of light for healthy plants.. but that seems to cry out for more discussion.

If I plant a tank heavily with fast growing stems, I go straight for the eight hour period. I do this because I am confident that the growth levels I can achieve from day one will keep the algae suppressed. However, my latest scape is relatively slow growing Crypts and mosses, with a very low plant mass. I have started with a photoperiod of four hours, because I know that despite all the precautions I take to remove ammonia, algae will appear. My recommendation to people starting tanks with higher light and CO2 to hold back to four hours at the start, and slowly increase the photoperiod to match the increased plant mass. It is algae that we are trying to control with the lights.

Spirogyra is my great nemesis, and is appearing after one month. The short photoperiod stops it becoming a runaway train. I will defeat the algae by promoting healthy plant growth as much as I can, using ferts and sky high CO2, but the light is the big engine that needs throttling back for the duration. If the Spiro persists, which it normally does, I will use a black out, or series of black outs to get rid of it, then start to increase the photoperiod to promote more healthy plant growth. I will keep doing this, always creating a hostile environment for the algae via plant health and keeping my foot of the throttle (lights).

So, the bottom line is, what is “enough” light….2 x reflected T8 tubes the length of your tank will grow anything. Just choose the colour (CRI) most appealing to your own tastes.

Once you realise that two T8s will do the job, you can forget everything else. Just ensure all ferts are non limiting, something that gets trickier as we decide to go for more light, particularly where carbon availability is concerned.

The pic below is my former 240l with two T8s the length of the tank. The Crypts are growing in inert fine gravel, which answers another thread on here about root tabs and keeping things simple. Dose the water column adequately, and you can grow any rooted plant.

Two reflected T8s the length of the tank, reduced EI, pressurised CO2 and inert gravel.

Dave.

 

[lljdma06]

If you post it...they will come.

Seriously, it is great that Dave has posted. Having used less light for a while now, I like how effective and simpler it is, though I really do not dwell much on the "whys" of it all. My first tank was 3+ WPG 15g and while it was pretty and plants grew fast, it was a hassle with regard to ferts and maintenance. Now, I rarely go above 2WPG and this is only when the tank is much smaller and only because the bulbs used for smaller tanks I have found less efficient.

llj

 

[Bobtastic]

At the moment I am running two tanks, both of them have live plants in them and both of them are extremely different in their lighting, high tech/low tech setup.

My first is a Juwel 800 Rekord, which is running 2 T8 tubes at, I think, 9-10hrs duration. Tho is has fairly "simple" plants in it they grow happily with no additional Co2 or ferts in the water column. There is also, not a massive amount of algae growth.

My second take is a 240litre tall tank that has 2 T5 39w lighting, again I think, running at 7-8hrs. Unfortunately I underestimated the need for balance in light, fert and Co2. So in the inset of the tank I had a lot of algae problems (which unfortunately are still lingering around now). With the addition of pressurised Co2 and recently the switch to homemade TPN+ (meaning that I can double dose without fear of my wallet having a heart attack!) Things seem to be getting on track!

I think my current problem is to ensure the ferts/Co2 get all around the tanks and some trials of powerhead positioning and possible extra powerhead it needed.

My point is that lower intensity at a longer duration seems to have delivered a tank with fewer demands and less complications!

 

[waterdrop]

OK, time for the OP to check in and give some feedback! My heartfelt thanks to the 3 of you for responding! I have just spent an enjoyable hour buried in the plant physiology text I found so that I could attempt to get up to speed on photosynthetically active radiation (PAR) and boy was it a reminder of just how difficult light really is to measure!

I had actually dashed off to read it hoping to find a reminder within the realm of physics about -why- photons can carry different energies (measured by their wavelength) but of course I didn't quite find that but instead ended up emersed in plant physiology, which was just as interesting.

Anyway, this hello is just to let you know that I'm here and reading and enjoying even if I now better realize the large size of the bite I attempted to chew in my question. It is clear from Dave's response that I will have to break this down for my further questions. Some of the "why" is all mixed in with the practical "doing" and I already regard his statement "so the bottom line is.. What is -enough- light?" as being right at the heart of what I was trying to get at - it has already "shaped my thinking" for the better.

WD

 

[atuin]

Wave length of light IS important for plant growth as photosynthesis speed changes depending on wave length of light. Most important parts of spectrum are orange and blue/violet. Low level of "orange" part of spectrum with high blue/violet can cause plants to grow "flat" - stops growth towards surface and promotes spreading to sides.
Fortunately amount of light have much higher impact on plants than quality of it

As for length of "day" - it has in some cases influence on plants look as some plants develop differently depending on length of day. Results can be similar to difference between emersed and submerged forms, probably due to plants in wild form going through emersed and submerged forms during change of seasons.

in some cases plant produce flowers only when length of "day" goes below or above 12h
Limnophila aquatica - in longer days grows faster but produces flowers only when under short day conditions

Sagittaria platyphylla - in opposite to above that one likes longer days - to get it flower it needs preferably +16h "day"

 

[lljdma06]

What is -enough- light?" as being right at the heart of what I was trying to get at - it has already "shaped my thinking" for the better.

WD

Hi WD,

I am trying to determine this question with a specific situation, so you can get an idea of the process I sort of go through when considering an aquarium I want to setup. Again, I am no expert in this at all, I just sort of plow through, and this reasoning has worked for me in the past. I've been reading this thread (yes, I am linking to another forum) from The planted tank about the new fluval Edge.

http/www.plantedtank.net/forums/planted-nano-tanks/95967-official-edge-thread.html

It is a very cool-looking tank and I am considering it possibly because the price has been marked down significantly. Somebody here recently got one for a present, I hope he sees this thread. The members in the above post have made many modifications to it to "make" the tank suitable for growing plants. Yet, there seems to be not a single member in that group who is willing to try the Edge with just its stock lighting. Is it really that bad? I've had crypts, mosses, and anubias grow perfectly well in almost complete shade in just stock-lit tanks. If one injected CO2 into the Edge, seemingly easy enough to do (I've seen the tank), could you perhaps just keep the stock lighting? I'm not a huge DIY person, and I think the modifications they are making tend to be overblown, especially since many of them are not growing extremely demanding plants in the first place (anubias, java fern, mosses, swords, crypts). There is a blind rush to make these modifications because someone told them to do it. So, "What is enough light" is a good question for this situation. From what I've seen of the tank, light distribution may be an issue, with most of the lighting concentration toward the center, but that suits an "island" scape quite well. They are also hallides, from what I understand, so things may get a bit toasty? I do not know, I have never worked with this lighting before. But salties seem to get on with hallides quite nicely. I have seen simpler modifications involving side lamps that I like better (doesn't increase intensity, but helps with distribution, involves no rewiring, and is not permanent), but if I purchased one, I would be tempted to try it "as is." Honestly, it can't be any worse than the lower levels of my 36g tank with only .77WPG. And that situation grows plants just fine.

Funny, when I first saw the Edge, besides going "Ooooooo cooool", my biggest concern was not the lighting, but the filtration. I tend to really over-filter my tanks. The filtration would be the turn-off for me regarding the Edge, not the lighting especially, and IMO, not worth it enough to purchase it and then make modifications to get better filtration. I do not know how the filtration is yet, I've heard good things about Fluval.

I apologize for my musings, but you get a sense of how I tackle "What is enough light?" when I consider a new setup. "What is enough light" for me is the light that I have to work with at that time. I then pick the plant species that I think will work based on my past experiences, some literature, and the experiences of others, though if I listened to others more in the beginning, I would probably have had more high-light tanks in my past scapes. I make some guesses and will try new plants just to see. When I first came here, A. reineckii and R. macrandra were typically considered high-light plants because they were "red". I grew A. reineckii in a low-light tank and SuperColey1 grew R. macrandra with less than 1WPG, and now a plant being "red" isn't such a determining factor.

llj

 

[Dave Spencer]

Wave length of light IS important for plant growth as photosynthesis speed changes depending on wave length of light. Most important parts of spectrum are orange and blue/violet. Low level of "orange" part of spectrum with high blue/violet can cause plants to grow "flat" - stops growth towards surface and promotes spreading to sides.

The problem is that anybody wanting to start planted tanks that are reading threads like this are instantly turned off planted tanks. Nobody needs to consider how much blue, violet or orange their plants will get. Go to a place like Lampspecs if you are in the UK, and buy a few tubes for the price of an aquarium specific Grolux, and see which look the best to your eye. None of the top aquascapers on planted tank specific forums are talking about spectrum etc.


I just don`t accept that the majority of hobbyists need to look beyond their stock lighting to grow most plants. Wavelength is largely irrelevant to planted tank hobbyists. It is how the tank looks to our eyes that is important. Keeping clear of pointless, so called "plant specific" tubes means we can buy more cheaper ones and experiment to achieve the desired look.


Like I said earlier, light and all its properties change throughout the day, so plants are not looking for a specific type of light. They adapt to what nature or the hobbyist (within reason) throws at them.

"Enough light" is simply the amount needed to achieve your goal. Stock lighting gets most jobs done, but I tend to go higher for faster growth rates. For me this hobby is 99% aquascaping, and 1% science.

If people really want to get in to the various aspects of light, then a new thread should be started in the science forum. I have resisted posting graphs relating spectrum to photosynthesis, because I think this forum should keep the emphasis on how easy planted tanks should be. Planted tanks are easy because all we need is stock lighting and TPN+ (or alternative). Further observations of the tank will determine whether a carbon supplement is necessary.

 

[lljdma06]

"Enough light" is simply the amount needed to achieve your goal. Stock lighting gets most jobs done, but I tend to go higher for faster growth rates. For me this hobby is 99% aquascaping, and 1% science.

Well said! I agree.

 

[waterdrop]

Yes, was certainly not my intent to go off on anything particularly technical.

Dave, what about Bobtastic's last sentence up there, that he feels longer duration at lower intensity has delivered a tank with fewer demands and less complications.

Let's take the case of so many of our newcomers over in the beginners section who might have a stock tank with 0.7w/g and a not very heavy planting of slow-growth plants. Is it likely that staying with that low an intensity but running it for 8 hours would work better than adding more light? And what about ferts? Is it overkill to suggest a small amount of dosing to people running an above type of light but who are not going to be running any CO2? Or in such a restricted situation is the tank better off simply with the waste of the fish? Or perhaps there's a different flaw in these types of questions in that for people experienced with plants there would be a pre-cursor in more detailed choosing of plants - perhaps its second nature to already know more about which species can take this sort of situation better?

I guess part of what I'm asking is how do you match the photoperiod to the plant mass in tanks such as these? What signs should they look for the dictate whether the photoperiod is too long or too short?

lljdma, we've had 2 or 3 threads in recent months on Edge tanks over in beginners and one of the most recent fellows gave up on his after 4 or so failures (impeller, tank cracks, I don't know what all.) There do seem to be a fair number of people trying various mods to see if they can make the things work to their satisfaction.

WD

 

[lljdma06]

I guess part of what I'm asking is how do you match the photoperiod to the plant mass in tanks such as these?

For newbies and newly scaped or setup tanks with the lighting your describe, I would usually start beginners at between 4-6 and see where that takes them. To be honest, when light levels are that low, things (including algae) happen quite slowly. Everything slows down. Most of these tanks are also not so densly planted and I like the shorter photo-periods on those tanks. I can personally go to 8 hours, but my tank is established and for a low-light, quite densely planted. It hurts nothing to be initially conservative. They got to watch their own tanks, though, different situations call for different measures. I can only give advice based on what I've personally observed, done, and read, but each Newbie can have a different situation.

Many of the newbies will not keep tanks as highly stocked as the established planted people. They tend stick to the inch per gallon rule (silly rule, IMO), so I do recommend some dosing. I know Walstad method advocates light stocking? Kind of a strange contrast. Does she advocate dosing? I'm not up to snuff on all of the methodology.

What signs should they look for the dictate whether the photoperiod is too long or too short?

Algae. Poor growth.

The biggest thing in the beginning for newbies are the ammonia spikes and the diatoms. They think the levels can be measured with the test kit. It is too small to be measured that way. In new setups, like you are describing, the ammonia is the major algae causer in the beginning and more waterchanges should be done to curtail the ammonia. This gets kind of weird later. When that hurdle is crossed, then, it is over-maintenance, IMO. These low-techers, unless grossly overstocked, do not require the weekly or 2x weekly maintenance that fish-only tanks or high-tech planted tanks. Hearing that you can go a couple of months without a water change (with only top-offs) is weird to process and not what they are hearing from other parts of the forum. While these low-techers with inert substrate cannot do the same as those practicing Walstad, they can go quite a bit of time between the waterchanges. In the low-tech world, excessive waterchanges make the limited CO2 unstable, which also triggers the algae. But they have to strike a balance. Right now, I am at 1 month approximately. Two months and the tank is far too tannic, even for me. Any more frequent than that and I do start seeing some more algae. All this goes out the window, though when I have done a heavy rescape. Then, you have to do more, otherwise the ammonia will cause more trouble than the unstable CO2. Again, all about balance.

Newbies also forget about ripples. You need lots of little, smooth ripples in the surface. Not breaking waves, but ripples. Good filtration and circulation is a must. Many opt to upgrade lighting first. I say, keep the stock lighting, upgrade the filter.

lljdma, we've had 2 or 3 threads in recent months on Edge tanks over in beginners and one of the most recent fellows gave up on his after 4 or so failures (impeller, tank cracks, I don't know what all.) There do seem to be a fair number of people trying various mods to see if they can make the things work to their satisfaction.

Yes, I saw that thread. IMO, the Edge is not a beginner tank. I would tell a beginner to get a 20g. I am still considering it. I'll read the thread again, though to see if the filtration is adaquate. If it don't have 10x turnover, than forget it, as cool as it may be.

I, of course, am probably all wrong, but again, I can only offer my opinion based on what I've observed and read.

 

[OohFeeshy]

I think the Edge filter does up to about 100GPH (well, it says it does), presumably to compensate somewhat for the reduced surface area with lots of agitation. It it adjustable though. Or if you wanted at a later date, it should be easy enough to fit a small external in the space left behind.

 

[waterdrop]

For newbies and newly scaped or setup tanks with the lighting your describe, I would usually start beginners at between 4-6 and see where that takes them.

OK, good, this seems to agree with what I feel I've heard from other planted tank members in the past and re-confirms that my advice to beginners in that direction is not way off base. I've been suggesting 4 hours and gradual increases if no algae is seen. I feel that many of these beginners with classic community tanks that don't plan to have heavy plantings should be sent over here later on to receive some advice on their -individual- situation and I'll probably try to be more regular about advocating that.

Many of the newbies will not keep tanks as highly stocked as the established planted people. They tend stick to the inch per gallon rule (silly rule, IMO), so I do recommend some dosing. I know Walstad method advocates light stocking? Kind of a strange contrast. Does she advocate dosing? I'm not up to snuff on all of the methodology.

About a year ago I participated in at least one thread where a lot of us agreed we would like to try and reduce the number of instances on the forum where the word "rule" is used with the inch guideline. As experienced fishkeepers (at least hopefully many of us have somewhat more experience than many newbies coming in) we usually understand the huge numbers of exceptions and problems with that guideline (and to planted folks running 10x or greater the problems might seem even more remote.) Nonetheless, the rough inch guideline can serve as a painted trail marker for beginners struggling with their stocking plan and I feel that getting a first year under their belt without all the troubles that overstocking can bring to the inexperienced is helpful. We still get newcomers with enormous fish overstockings in small tanks with pitiful little filters. In some cases these newbies are unable to even cycle the tank - its just a totally different situation than the serious hobbyists that permeate the planted section.

I think bringing Walstad method in to the discussion broadens it too much, but I will say that she usually relishes it when her tanks need no dosing, although I believe she will do some small dosing for particular problems on occasion. I believe part of her advocation of light stocking is related to her desire to do almost no water changes. I am unsure of the soil reactions which provide carbon to Walstad method tanks without looking it up but that's a crucial aspect of that method. Another strong contrast that I continually notice between Walstad and traditional mainstream aquascaping is a complete style contrast, the typical Walstad practicioners often enjoying a "jungle" which is to some extent non-scaped as contrasted with "scaped" being often "the point" of the hobby for much of mainstream aquascaping. The area where Walstad and mainstream (I'm using that simply as a shorthand to lump lowlight and hightech together) do share a lot is in the health and beauty of the plants themselves - this is a goal in all 3 methods as far as I can tell. Note that it would not be fair for me to speak for Diana and I hope I don't sound like I'm doing that.

...excessive waterchanges make the limited CO2 unstable, which also triggers the algae...

lljdma06, do you think unstable CO2 (in tanks with no pressurized or DIY) has any effect on diatoms? My own observations completely support the advice that BBA is promoted by it, but I wonder about diatoms. Dave has indicated that low carbon is probably the major factor that keeps diatoms going assuming there's been trace ammonia to get it started. But maybe some think that fluctuating CO2 from large, frequent water changes is an additional factor?

WD