Low tech lighting levels

[Andy Thurston]

Look at my step by step in my signature. there are photos of hc that were in the propagator before i restarted it and i believe that the yellowing of the lower parts of the plant was caused by the shade from the top half of the plant there were no other factors that it could have been. Each plant has different minimum light requirements so potentially not enough light could be a problem.

 

[foxfish]

However that was an interesting post that George put on the London aquarium thread!

 

[Guest]

Crypts truly are amazing plants...they always seem to do well. Mine thrive in low light, soil, and hard water. Anyway, I think that part of the problem - in general - and to the point, regarding plant growth and lighting levels, is that so much of our experience is anecdotal and unquantifiable, and whilst this is often OK it's sometimes easy to overlook or exaggerate certain factors to fit perceived outcomes...And I think it's something we are all guilty of at sometime or other...and ultimately it can be confusing or lead to the wrong conclusions - philosophically speaking😵

 

[sciencefiction]

However that was an interesting post that George put on the London aquarium thread!

Is that about the crypt that grew in his garage in 99% unlit and unpowered tank? This only goes to show that a particular species of crypt can grow in very low light. One may claim crypts don't need CO2 either in that case. ....But how about the overall health of the plant and it's leaf structure? I literary planted two aponogeton bulbs at the same time, under the same spraybar inside the same tank but two different light levels, one is looking like it's fighting for its life, the other is healthy and growing as it should. Ceg is claiming that the poor unhealthy growth of one of them is because it has less CO2 in there, compared to it's brother about 30 cm apart who is under the same spraybar(working fine and not blocked) but has more light. It's worth saying that neither is melting and has holes or any other damage indicating CO2 issues and the tank hasn't had any algae issues since setup, besides diatoms at the start. The water level is down due to the tank leaking but I just took a couple of picture of the leaves of the two aponogetons outside the water.

Low light aponogeton:



These were the two longest leaves I could take out of the water. Please excuse the fingers.



Higher light aponogeton:

 

[Michael W]

I have a question regarding the growth of my ludwigia repens in my low tech tank. It's situation is fairly similar to this topic so I won't most a new thread. I had trimmed one of the stems down since switching substrates. The stem I replanted was around 10cm tall and the left over stem had only two leaves on it which are the emersed form. Since I thought the two leaves were pretty healthy, I decided to leave it in the tank until it fully degrades hoping in the mean time it will send new growth in the form of submerged leaves. This surprisingly worked out quite well. Now the strange thing is both the stems were planted in different locations, the emersed was right next to the spray bar having a lot of flow and the other was at an area with little to no flow, the stem next to the spray bar has since shown around 5cm worth of growth and yet the other around 2cm. I found this quite strange since the replanted stem had so many leaves yet it grew slower than the other stem which still has its emersed leaves along with the new growth. What does this tell me? Does it mean really mean flow is THAT important? I have knowledge from reading posts and offer what I have gained from the posts but lack first hand experience to back it up. So the answer to this will give me a bigger confidence boost to my knowledge or improve it and give me an example which i can share.

 

[sciencefiction]

By the way, here is a picture of the tank from a few months ago. It was soon after I put the emersed plants on that side. You can see on the picture the aponogeton on the left has not grown one bit since if you compare the before and after pictures. That's the advantage of taking a lot of pictures. Compare to the aponogeton behind the amazon swords and ludwiga on which you can see the tips only at that stage. So they were still the same size at that point. However shading one of them has made the difference in appearance and size.

 

[Michael W]

I found this article on tropica's website which may help in this discussion too. Hope it will be of use as a reference.

Tropica Aquarium Plants - Rådgivning - Tekniske artikler - Vandplanters biologi - Interaktioner mellem lys og CO2

 

[sciencefiction]

And I am sorry to hijack the thread so much but I found a video too and dug up my dates. I've put the emersed plants on the 19th of May. The video below is from just over two weeks after that. You can see the growth of the two aponogetons up to that point. They are shown between 0:10 and 0:30 seconds at the start of the video. Bothe are the same size at that stage. There's been no change in flow setup at all and if anything was overgrown since that could have blocked flow and CO2(in a non-CO2 tank by the way), then it would have been the healthy aponogeton in the middle because the amazon swords, vallis and ludwiga took off.

watch between 0:10 and 0:30sec.

 

[Ady34]

I found this article on tropica's website which may help in this discussion too. Hope it will be of use as a reference.

Tropica Aquarium Plants - Rådgivning - Tekniske artikler - Vandplanters biologi - Interaktioner mellem lys og CO2

was just about to post that very same article 🙂 Tom Barr presented it here not long back and it was very interesting.
Low light and low c02 is the worst case scenario yielding little growth. High light and low c02 yields more growth (plant mass), but low light and high c02 yields double the mass gained (both high light and high c02 obviously create the biggest gains). Light definitely plays a role, and is the accelerator, but c02 is the go go juice without which you wouldnt be able to grow fast without conking out!! The article is much more detailed regards the plants growth mechanisms which is worth understanding before too many conclusions are drawn.....too much light obviously negates the positive effects and leads to melt. What is meant by high light is also slightly vague in this instance, perhaps it is just a little more than the lcp? I imagine that the effects, tolerances and success levels vary from species to species also.
Taken from that article:
"Table 1 shows the results of these experiments expressing the growth rate of Riccia fluitans in percent per day, while assuming exponential growth over the period (1). We see that at low light and low CO2 Riccia fluitans is barely able to maintain a positive growth rate whereas at low CO2 and high light the growth rate is almost 6 fold higher. More importantly, at low light levels the addition of CO2 is able to stimulate the growth by a factor of almost 4!
Maybe a stimulation of the growth rate by a factor of 4 to 6 does not seem much but because of the exponential nature of the growth rate it really makes a difference over a period of, for example, two weeks. Figure 3 shows how 1gram of Riccia fluitans develops over two weeks with four different growth rates. Low light and low CO2 barely result in positive growth over the two weeks, whereas the treatment with high CO2 and low light translate into almost a doubling of the tissue weight. For comparison, the high light and low CO2 result in 2.5 gram of tissue after two weeks. It is needless to say, that the benefit from increasing both light and CO2 surpass the effect of raising only one parameter. At the highest light and CO2 availability, 1 gram of Riccia grows into astonishing 6.9 gram after two weeks. Surprisingly, the stimulation observed on the growth rate when both light and CO2 are increased is larger than the additive contribution from each individual parameter. Example: The growth rate at low light and low CO2 is 1.1% per day. By increasing light, the plant grows 3.3% per day or an additional 2.2% compared to the starting condition. Similarly, by increasing CO2 the growth rate is now 3.8% per day or an additional 2.7%. An additive relationship would then translate into 6.0% per day (1.1 + 2.2 + 2.7) but the resulting growth rate from combining light and CO2 is 9.2% per day, which is significantly larger. This tendency also holds when moving even higher up in light and CO2"

In a low tech tank it can be expected that c02 levels are low, in the same tank in the shade, both light and c02 will be low so growth will be much reduced which is likely what you are experiencing sciencefiction. Clive isnt wrong as more c02/ferts will yield better growth, but i suspect in your particular low tech tank that light may be the limiting factor.
Cheerio,
Ady.

 

[hotweldfire]

I found this article on tropica's website which may help in this discussion too. Hope it will be of use as a reference.

Tropica Aquarium Plants - Rådgivning - Tekniske artikler - Vandplanters biologi - Interaktioner mellem lys og CO2

This is a really useful page. Effectively what the tropica experiment shows is that both light and co2 affect plant growth. So it is not the case that you cannot underlight an aquarium. For example they state

Both fluorescent light and highpressure-quicksilver lamps may produce sufficient light if supplied with effective reflectors but in deep aquaria (more than 50 cm) is very difficult to offer enough light to small light demanding foreground plants.

At the same time they state

Based on our experiments, we suggest commencing CO2 addition before any other action is taken!

Crucially light and co2 interact to affect plant growth. I remember a1matt once writing on this forum that in his low light tanks he used to run a tiny amount of injected co2 and found the plants did better than without it. At the time I thought "what's the point of that"? The answer is that a bit of co2 allows the plants to use the light more efficiently. What's interesting is that the opposite also appears to be true:

High light availability may also allow aquatic plants to lower the CO2 compensation point (Maberly 1983, Maberly 1985). This may be particular advantageous for mat-forming photoautotrophs in shallow water. In such systems, the light is often abundant whereas concentrations of CO2 inside the mat are low due to low intra-mat water exchange. Here, the interactions between light and CO2 may allow the photosynthesising organisms to extract CO2 more efficiently as a result of a lowered CO2 compensation point.

I.e. higher light levels allow plants to better take advantage of existing co2. It may be that this is specific to certain species or it is possible that I'm misinterpreting this. If not though, this would seem to run counter to the prevailing EI orthodoxy. I.e. higher light is bad. On the basis of this Tropica article, higher light allows for more efficient use of co2 so higher light is good. Certainly it was the case in the Tropica experiment that plants in high light and low co2 grew faster than in low light and high co2. What's not reported is the health of the plants.

 

[sciencefiction]

In a low tech tank it can be expected that c02 levels are low, in the same tank in the shade, both light and c02 will be low so growth will be much reduced which is likely what you are experiencing sciencefiction. Clive isnt wrong as more c02/ferts will yield better growth, but i suspect in your particular low tech tank that light may be the limiting factor.
Cheerio,
Ady.

Yes Ady, seems that no one is wrong. However, it seems poor growth is not just down to CO2 but light too in particular scenarios like mine when there's no CO2 supplement, and one can compensate light with co2 and vice versa to an extent to get healthy growth. That's how I read it and my tank is an example of what's happening to the shadow corner in my tank.

We see that at low light and low CO2 Riccia fluitans is barely able to maintain a positive growth rate whereas at low CO2 and high light the growth rate is almost 6 fold higher. More importantly, at low light levels the addition of CO2 is able to stimulate the growth by a factor of almost 4!

And see their reasoning why providing CO2 is more desirable than light.....because they think one can still have inadequate light for particular species of plants in aquarium with the light we currently use if the tank is too deep. So adding CO2 instead is about compensating the plants for the lack of light down there. Hence why it's accepted that carpeting plants need lots of CO2 instead. But in my low tech the glosso is growing without CO2, so it must be getting adequate light to an extent. My tank is only 50cm so that's possible the reason it grows as I have high power LEDs over the tank. (forgot to say the glosso is carpeting and not leggy at all)

It is often a much more difficult and expensive task to provide adequate light over the plant aquarium. Both fluorescent light and highpressure-quicksilver lamps may produce sufficient light if supplied with effective reflectors but in deep aquaria (more than 50 cm) is very difficult to offer enough light to small light demanding foreground plants. Based on our experiments, we suggest commencing CO2 addition before any other action is taken

 

[Ady34]

It would be useful to know what "high lighting" levels are though. I suspect it is actually a lot lower than the kinds of light we choose to put over our tanks which is why we end up melting our plants even with co2 addition. Science fiction seems to have hit the right balance in that their plants are healthy and growing in the most part, if their tank were a high tech system with good flow/distribution of the co2 the difference between growth of the aponogeton a would be less obvious I suspect.
It seems plants can adapt strategy to light or co2 collection depending upon availability...they are not so good when both are limiting.

 

[Ady34]

And see their reasoning why providing CO2 is more desirable than light.....because they think one can still have inadequate light for particular species of plants in aquarium with the light we currently use if the tank is too deep. So adding CO2 instead is about compensating the plants for the lack of light down there. Hence why it's accepted that carpeting plants need lots of CO2 instead. But in my low tech the glosso is growing without CO2.

Well, not entirely as the article shows that co2 grows more plant mass, light dictates the speed at which they try to grow. Small foreground plants need more light to grow faster to fill in the space faster, we are impatient in the most part so it is desirable to have high light to speed up the process and get a 'carpet'.....however without matching the co2 to the light we end up in trouble. In your instance without co2 addition the plant will require less light to succeed but will grow at a much slower rate.
It is safer (plant health wise) to add more co2 and less light as that way you run into fewer issues either algae or melt.

 

[sciencefiction]

Yes, the rate of growth is affected but not the health of the plant unless one goes extreme I guess. But at least now I understand why I have no problem with carpeting plants growing fine in a low tech enviroment without CO2. I might as well take a lot of pictures as the tank is coming down soon. But here is my glosso and bacopa australis carpeting in that same tank. Some of you may have seen it already. I don't have even one strand of glosso growing upwards, starving for CO2 as what's normally pointed out as a main reason. So regarding of theories, I either have very high CO2 in my tank or that article is right that light can compensate to an extent if fertilization is right. Yes, they are not growing very fast but they are growing.

That's after planting the glosso.




That's it today.

 

[Ady34]

The article I'm sure is right, but we don't know the levels of lighting used. Light can compensate to a degree, but not entirely.
In your tank I'm sure the lighting and available co2 are well balanced which is why your experiencing good healthy growth, albeit a little slower 🙂 Maybe glosso is a species particularly good at converting water carbonates into useable carbon like vallis which is also doing well in your tank. There can be more variables and pieces to the puzzle which we may never know.
If you had longer time available you could increase lighting intensity and see what happened, I would suspect structural failure as the plant could not feed itself fast enough without co2 and fertiliser addition. You could also swap the two aponogetons positions and see what happened to them without altering any other variables (like I say it may well be light in this instance which has created the difference)...but as you say you have to take the tank down, and I'm sure even if you didnt have to you wouldn't want to potentially ruin the balance as its going so well. I'm sorry to hear about the leak, hope you get it resolved as the tank is doing really nicely now, 'from the Disaster to Success' may be a better title for it now 😉
Cheerio,
Ady.

 

[sciencefiction]

That's what it says about the light and CO2 levels in the article without specifying much:

High light corresponds to light levels found in nature near the water surface or in an extremely well illuminated aquaria with high-pressure mercury lamps or halogen lamps. In fact, the medium light intensity in this study corresponds to a standard well illuminated plant aquarium. Low CO2 corresponds to the CO2 concentration found in many lakes or in an aquarium without CO2 fertilisation - but with an aerating pump running. High CO2 is 40 mg/l, which can be found in many small groundwater feed streams and it is also the maximum level recommended by most experienced plant aquarium keepers.

At very low light intensities, the incident light is insufficient to sustain a positive photosynthesis and the net oxygen budget of the plant is negative. In other words, the respiration processes exceed the photosynthesis. At a certain light level, however, the two processes equal each other and we have then defined the light compensation point of the plant. By illuminating the plant with still higher light intensities the photosynthesis is also positively stimulated in linear way. At high light, the resulting outcome from the photosynthesis becomes less until it finally levels out at a point where we have the maximum photosynthesis. From this point on, more light will not translate into a greater photosynthesis.QUOTE]

 

[sciencefiction]

Maybe glosso is a species particularly good at converting water carbonates into useable carbon like vallis which is also doing well in your tank.

I didn't even know glosso can do that. I know about valis, hence it grows better in harder water and almost anyone can grow vallis. But in my case it took quite a while for it to take off and it wasn't the first plant to recover so I don't think it's indication of anything but who knows.

Vallis on the 30th June 2.5 months after planting(a few strands visible halfway the height of the tank out the back.




Vallis on the 4th August finally taking off, but the same did the rest of the plants.

You could also swap the two aponogetons positions and see what happened to them without altering any other variables (like I say it may well be light in this instance which has created the difference)

I could just remove the emersed plant pots and the light will be unblocked again to that aponogeton and the surrounding plants. I just can't do that right now but I would have and even before posting today here I've been thinking for a few weeks where to move the emersed plants without compromising other plants like that. If it comes to taking the tank apart completely, I'll switch the aponogetons around or just plant both in the middle back somewhere and keep the corner to anubias and crypts only and hopefully vallis or whatever else I can find that can deal with that shadow.

 

[Guest]

I read this article well over a year ago and it's apparently become something of a Bible...in that it seems to be grossly misunderstood or open to interpretation depending on your religion...or rather preconceived ideas and/or dogmatic devotion to certain paradigms. For instance, take the opening quote...

'Poor growth in plant aquaria has usually been attributed to insufficient light over the tank and when asking the experts, the advice has always been to increase the light availability before any other action is taken. New research shows that this may be poor advice, in particular, for an aquarium without CO2 fertilisation'

This is very true and I'm not going to argue against this at all...however the key phrase is "the advice has always been to increase the light availability before any other action is taken"...this does not mean that in - some, a lot, or even most cases light and not CO2 is the main limiting factor to growth...it just means that we should ensure other variables - CO2, fertz, and flow and distribution - are sufficient first.

I can't be bothered to read the article again but from what I remember the results of the research actually indicated that high light and low CO2 provide better growing conditions than high CO2 and low light, but together high light and high CO2 can provide optimum growth rates (whatever the authors definition of high and low light/CO2 are, but I imagine you don't have to look any further than their plant catalogue to find out). In fact, the overall assumption of the paper is that light is indeed often the limiting factor to growth, but it nevertheless advocates the use of CO2 to further increase plant growth.

So in conclusion perhaps blaming all our tank woes on low CO2 is not always right or particularly helpful...it could actually be that in many cases the "experts" are right to advise increasing light availability...but just as long as all the other parameters are adequate too...certainly my own experience corroborates this.

Just one more point on plant LCP - yes you can grow plants at PAR levels just above it but they ain't gona be very happy nor are they gona float anyone's boat aesthetically...

 

[Ady34]

Troi, the article shows that high co2 and low light yields much greater plant mass gain than high light and low co2. Low co2 is a greater inhibitor than low light hence the advice to keep light low and try to optimise co2, especially given how notoriously tricky it is to keep the darn gas in the tank and put it where we need it. Co2 is the daddy, especially in our high tech tanks. Good proportions of co2, ferts and light are the most productive scenario, but that's harder to hit the sweet spot.....infact I've never hit it yet 🙂
Cheerio
Ady

 

[sciencefiction]

Troi, the article shows that high co2 and low light yields much greater plant mass gain than high light and low co2. Low co2 is a greater inhibitor than low light hence the advice to keep light low and try to optimise co2, especially given how notoriously tricky it is to keep the darn gas in the tank and put it where we need it. Co2 is the daddy, especially in our high tech tanks. Good proportions of co2, ferts and light are the most productive scenario, but that's harder to hit the sweet spot.....infact I've never hit it yet 🙂
Cheerio
Ady

I think Troi is right. See figure 3 to the right side of the article and here is the explanation from it:

The figure shows how 1 gram of Riccia develops over two weeks under the given light and CO2 levels. At low light and low CO2, Riccia is barely able to maintain the biomass and 1 gram turns into 1.16 gram after two weeks (the white line). At low light and high CO2, 1 gram turns into 1.75 (the green line) and at high light but low CO2, 1 gram turns into 2.41 gram. The combination, however, paramounts the effect from the individual resources and at high light and high CO2, 1 gram turns into 6.90 gram.