Hygrophila polysperma alternative?

[Quetzalcoatl]

from experience the cheaper tubes are less powerful and used for more domestic purposes (i.e. used as a kitchen light).

Not true mate. Like you, I was dubious when introduced to the option of cheap tubes! It`s a total travesty that manufactures can get away with fleecing the unknowing hobbyist of their hard earned cash. £20 you say for the Hagen tubes? WTF... I was using Arcadia Tropical for a while until someone pointed me in the right direction. I made the change, my plants and my bank account loved me for it.

Check out the links below.

http://www.theplantedtank.co.uk/lighting.htm

http://www.lampspecs.co.uk/Light-Bulbs-Tubes/Skywhite Bear in mind they are a bit more expensive than I pay, but I`m lucky, I have a freind who runs a Electrical Suppliers.

 

[dw1305]

Hi all,
I like Amazon Frogbit/Salvinia and/or Pistia as a light diffuser, it allows you to create light and dark areas, diffuse the light, is a nutrient "sponge" and has great roots for fry etc. I can't imagine I'll ever have a tank without them.

....... the cheaper tubes are less powerful and used for more domestic purposes (i.e. used as a kitchen light).

Liam is definitely right, in fact if you look at George F's recent post in this thread <http://www.ukaps.org/forum/viewtopic.php?f=50&t=19691>.

The client had 4 x T8 fluorescents over their Juwel Trigon 350. I believe the Juwel ballasts are electronic, even the old T8 type. The bulbs were old, at least 18 months. 2 x Hagen Power-Glo, 2 x Life-Glo. I tested the PAR at the substrate using an Apogee meter. With the old tubes it was less that 10umol in the corner. With the new tubes it was over 20umol. Same brand and model type.

The figures from the PAR meter strongly suggest that the Hagen tubes have halophosphate phosphors, which are much less efficient than the triphosphor phosphors used in nearly all recent T5/T8 tubes.

Based on this I would expect any off the shelf "daylight" fluorescent tube to produce more PAR than the Hagen equivalent.

cheers Darrel

 

[mark4785]

The tubes from Lampspecs have a lesser kelvin level compared to the Hagen tubes that I use and there is no mention of the kinds of photosynthetically active radiation (PAR) that emit from them, i.e. the colours of the light being emitted such as reds and blues.

When you consider that the Hygrophila polysperma are growing small under 2 x 24w 10,000 Kelvin Hagen lights (with floating Frogbit blocking some of it out), switching to a Lampspecs light which only emits 8,000 Kelvin (with no mention of PAR) will cause growth to become even smaller, right?

 

[Quetzalcoatl]

Hi mate. I`ll have a go at answering your question, but bear in mind I`m no Guru, and am still learning myself.

As I understand it, plant chlorophyll absorbs light most efficiently when exposed to a colour temperature of around 6500K. This best imitates natural daylight. An 865 Daylight Triphosphur tube like the one I linked for you will emmit the full spectrum of light Red, Green, and Blue but will spike more in the red hue.
Tubes with lower K ratings (3000) tend to spike more around yellow, which aint great for photosynthesis, where as higher rated tubes like your 10,000K will be peak more in the blue. Great for corals, not so great for plants?

Whilst I was doing my own research a while back regarding lighting I found this extremely comprehensive, all be it long winded article. It was extremly helpfull. Have a read, hopefully it will better explain the science than I can?
http://www.americanaquariumproducts.com/Aquarium_Lighting.html

Honestly though. From first hand experience, after swapping tubes to the 865 TRIphosphur Daylight tubes, I have had great results. I have a 500mm deep tank and the light has no problem punching through to the substrate. I have had HC, and Glosso pearling using them!

 

[ceg4048]

...As I understand it, plant chlorophyll absorbs light most efficiently when exposed to a colour temperature of around 6500K.

No, this is not true. Chlorophyll does not care about Kelvin. The response curves are based on the specific wavelengths of light as shown on the absorption spectra below. You can see that the two major Chlorophyll molecules resonate at the blue end of the spectrum (with their peak response at 453 and 430 nanometers) and at the red end of the spectrum (with their peak response at 642 and 662 nanometers). These two pigment molecules do not respond very well at all to wavelengths between about 500 to 600 nanometers.

However, there are a lot of other pigments produced, such as Carotenoids, Phycocyanins, Phycocrythrins and so forth which fill that gap. These are called auxiliary pigments, and although nobody ever talks about these, they are the pigments responsible for the various colors (other than green) that we see in plants. The plant will produce just the right amount of each pigment to make use of the wavelengths of light that are available. Below you can see the absorption spectra of several other types of pigments in comparison to Chlorophyll.

That's why it is folly to think about Kelvin ratings of bulbs, which in fact are a complete scam anyway because no bulb actually produces light at their stated Kelvin temperatures. These are all just marketing ploys and are at best, general guidelines as to how a bulb looks. If all bulbs at a given Kelvin rating were put side by side then they should look indistinguishable from each other, but of course, that doesn't happen. This renders all kelvin ratings more or less an illusion. NO BULB can imitate daylight. At best, based on their combination of phosphors, they emit peaks and valleys of energy at various wavelengths that you brain simply interprets as this color or that color.

As a result, any bulb is good for plant growth because it simply does not matter to the plant what the bulb spectrum looks like. The plant simply assess the radiation present and produces a potpourri of pigments that maximizes the response to the wavelengths available and reflects wavelengths that have energies which are too strong (or which are harmful, such as some types of UV.)

This is why Kelvin ratings and other illusions are completely irrelevant and why you can grow plants with any bulb as long as PAR is above LCP and is not too high as to cause too much photo-inhibition.

Cheers,

 

[dw1305]

Hi all,
This should now say "read the post above", but as I've typed it all out I'll leave it up.

The tubes from Lampspecs have a lesser kelvin level compared to the Hagen tubes that I use and there is no mention of the kinds of photosynthetically active radiation (PAR) that emit from them, i.e. the colours of the light being emitted such as reds and blues.

Unfortunately without a PAR/PUR meter it is difficult to compare tubes directly, but you can use the specs. of the tube/ballast unit to give you an idea.

For the ballasts, electronic ballasts are more efficient than magnetic ones, and all newer T8 and T5 fittings will be electronically ballasted.

Thin diameter tubes are more efficient, so a T5 tube will produce more light than a T8 tube of equivalent wattage. Linear tubes are more efficient than compact fluorescent (CFL) fittings and the more turns in the tube the less efficient it is. Fluorescent tubes are "discharge lamps" which produce UV, this is then converted to visible light by phosphors on the inside of the tube, modern lamps are all "tri-phosphor" and produce a wider spectrum of wave lengths than single phosphate tubes. Lamp lumen maintenance is how well light intensity is maintained over lamp life and it is above 90% for electronically ballasted tri-phosphor T5 tubes.

Wattage is a measure of the energy used by the fitting and it can't be compared across tubes and fittings in terms of light produced. Lamps are now quoted in lux values, this is how bright a light is compared to a "standard candle". Lux values are of very limited value, but as a very general rule of thumb you need about 500lux to support any plant growth (this will be LCP (light compensation point) for mosses etc, most higher plants will need more than 1000lux). Lux vales decline as the square of the distance from a point source (the light spreads in a cone, therefore more coverage = less intensity).

Kelvin (K values) is the light colour compared with a the irradiation of a "black body" (an idealised radiating object) heated to that temperature in degrees Kelvin (degrees centigrade + 273). The higher the colour temperature, the bluer the light. These are the colour temperatures of some light sources: Open sky - approx 20,000 K, Overcast sky - 6,500 K, Direct sunlight - 5,400 K, 100 Watt tungsten bulb - 2,865 K & the "standard candle" flame - 1,930 K.

The other value often quoted is the CRI (Colour Rendering Index) , this is how closely the light mirrors daylight, high CRI values mean that colours will appear similar to under daylight to the human eye.

None of these measures are directly relevant to plants, they are all measures of human visual perception. Plants have evolved to use light from the sun, which is why "daylights" have a colour temperature of 5000 - 7000K. You also have to take into account the wavelengths utilised by chlorophyll.

There are accessory pigments that mop up some of the light not utilised by chlorophyll a and chlorophyll b as well.

What does this all mean? it means that you can use any lamp from 2000K up to 20000K, those about 5000- 7000K are likely to chuck out more PAR, but we can't measure this directly without a PAR meter.

Based upon some experiments with Cabomba and various grow-lights <http://www.saps.org.uk/secondary/te...n-evolution-in-the-process-of-photosynthesis->, the "best" light I have is a mixed Red & Blue 13.8w "300mm x 300mm 225 LED Tile" bought for £20 from Amazon.

cheers Darrel

 

[Quetzalcoatl]

No, this is not true. Chlorophyll does not care about Kelvin.

So I failed my exam then? Thanks for clearing that up. like I say, I`m still learning!

 

[mark4785]

As a result, any bulb is good for plant growth because it simply does not matter to the plant what the bulb spectrum looks like. The plant simply assess the radiation present and produces a potpourri of pigments that maximizes the response to the wavelengths available and reflects wavelengths that have energies which are too strong (or which are harmful, such as some types of UV.)

This is why Kelvin ratings and other illusions are completely irrelevant and why you can grow plants with any bulb as long as PAR is above LCP and is not too high as to cause too much photo-inhibition.

Cheers,

So the colour spectrum of a given bulb only serves an aesthetic purpose with regards to what the light looks like to the eye?

What does LCP mean and why does PAR need to be above it?

 

[mark4785]

Hi mate. I`ll have a go at answering your question, but bear in mind I`m no Guru, and am still learning myself.

As I understand it, plant chlorophyll absorbs light most efficiently when exposed to a colour temperature of around 6500K. This best imitates natural daylight. An 865 Daylight Triphosphur tube like the one I linked for you will emmit the full spectrum of light Red, Green, and Blue but will spike more in the red hue.
Tubes with lower K ratings (3000) tend to spike more around yellow, which aint great for photosynthesis, where as higher rated tubes like your 10,000K will be peak more in the blue. Great for corals, not so great for plants?

The bulb I use emits a range of colours which apparently are configured best for plant or marine use. It would appear that the colours emitted by a bulb is not important according to what is being discussed here.

 

[dw1305]

Hi all,

What does LCP mean and why does PAR need to be above it?

It does say somewhere in the above posts, but LCP is "light compensation point", this is the value at which the net production from photosynthesis becomes positive. This is why you can't compensate for low light levels with a longer lighting period, if the PAR doesn't reach LCP the plant will die.

Plants that are adapted to low light conditions have a low LCP value, and combine very slow growth with a lot of chlorophyll, and for higher plants/ green algae are inevitably dark green. The slow growth is caused by a combination of factors, amongst them the low energy input, the cost of producing all that chlorophyll (a protein) and of producing secondary metabolites to make the leaf unpalatable (you have to protect your chlorophyll). They also will have low "light saturation point", meaning that they can't utilise high light levels, which may also cause damage (all that "spare" energy).

Bryophytes should grow at lower LCP values than higher plants, see <http://www.bryoecol.mtu.edu/chapters/11-3PhotoLimits.pdf> & <http://www.bryoecol.mtu.edu/chapters/9-1LightShade.pdf>, both well worth a read.

Most bryophytes are adapted to capture of low light intensities due to their one-cell-thick leaves and lack of well-developed cuticle. Responses of bryophytes to low light are similar to those of tracheophytes, with increased chlorophylls and antenna pigments, depressed light saturation and compensation points, and deeper
green color. However, some bryophytes at least do not have a lower chlorophyll a:b ratio in low light compared to high light, as would the typical tracheophyte. Rather, bryophytes in general have a lower chlorophyll a:b ratio in all light conditions than do tracheophytes. This suggests that the bryophyte, with its chlorophyll a concentrations maintaining
proportionality to chlorophyll b concentrations, would be ready for brief opportunities when bright light becomes available. Liverworts seem to be better adapted to shade than mosses, with a lower chlorophyll a:b ratio, higher concentration of total chlorophyll, and lower PPFD.

The Red Algae (Rhodophyta, like BBA) will grow at light levels below the LCP for all plants containing just chlorophylls, due to their phycoerythrin accessory pigments. You would need to be able to measure PUR rather than PAR for these, PPFD is photosynthetic photon flux density, so another measure of PAR (light is composed of photons).

Have a look at this post: <http://www.ukaps.org/forum/viewtopic.php?f=50&t=11971>.

cheers Darrel

 

[ceg4048]

...So the colour spectrum of a given bulb only serves an aesthetic purpose with regards to what the light looks like to the eye?

CORRECT!!

Cheers,

 

[scottward]

I have heaps of experience with hydro polysperma melting. It is very very fussy with co2 stability. Ceg is correct, co2 distribution is the culprit, not light.

 

[scottward]

P.s. Even though everything else seems fine and flow and co2 injection looks good.

Ceg, perhaps reg quality, surging, temp fluctuation?

 

[ceg4048]

Ummm...well, these can be contributory factors but fundamentally, there is either too much light or not enough CO2 - whether that's by virtue of poor flow/distribution or by inadequate injection rate. The problem we have in identifying root cause is that we have fish in the tank which makes it difficult for use to use radical approaches to problem solving. That's why it's worth having a fish free tank so that we can really go to town. I've seen amazing H. polysperma tanks grown non-CO2 - but of course the light energy reaching the plants is very low. Yet, the plants still grow nicely and still have their beautiful pink veining.

Once you add a lot of light though the plant needs much more CO2 to keep up the demanded growth rate. In my tank this plant is a nuisance because it's capable of outgrowing any other submerged plant. I mean, the speed of growth is alarming. It's like a virus, and so it easily takes over the tank, covering everything in it's path like a pestilent cloud of red locusts. This plant is on my banned list. So if you have melting leaves on this plant then you have a serious CO2 deficiency mate. Of that there can be very little doubt. You now have to question both your light intensity as well as your CO2 diffusion and/or injection technique(s).

Cheers,

 

[Ady34]

Hi,
i have hygrophila polysperma rosanervig, its a weed, but isnt giving the pink colouration, any ideas on that?

 

[scottward]

So if you have melting leaves on this plant then you have a serious CO2 deficiency mate.

I think deficieny is the wrong word - I think you really mean a stability problem here Ceg?

The stuff will grow pretty good without CO2 supplementation, as long as the light is low. I grew it for years just like this and it did well.

It was only when I started supplementing CO2 that I started having problems with it.

The CO2 has to be rock solid stable. Any fluctuation in the CO2 level around the leaves of the plant, as a result of inadequate circulation, or some technical problem, will see this plant failing.

I have my tank set up with a horizontal gyre (spelling?) stye flow, and I can see particles circulating nicely about the tank. All plants did well except this one.......really bloody fussy!

Scott.

 

[ceg4048]

Hi,
i have hygrophila polysperma rosanervig, its a weed, but isnt giving the pink colouration, any ideas on that?

There's a variety called "sunset" and another from Tropica called 'Rosanervig" that has the pink veining. The regular just has the white veining.

So if you have melting leaves on this plant then you have a serious CO2 deficiency mate.

I think deficieny is the wrong word - I think you really mean a stability problem here Ceg?

The stuff will grow pretty good without CO2 supplementation, as long as the light is low. I grew it for years just like this and it did well.

It was only when I started supplementing CO2 that I started having problems with it.

The CO2 has to be rock solid stable. Any fluctuation in the CO2 level around the leaves of the plant, as a result of inadequate circulation, or some technical problem, will see this plant failing.

I have my tank set up with a horizontal gyre (spelling?) stye flow, and I can see particles circulating nicely about the tank. All plants did well except this one.......really bloody fussy!

Scott.

No, I really do mean deficiency. H. polysperma has to be the least fussy of all plants, but because of the intense growth rate it often runs out of CO2 before the other plants do. If you had a stability issue then the problem would most likely show up as BBA, not melting/falling. Melting and falling leaves in any plant is due to poor CO2 at the location where the leaves are falling or melting.

People say all the time that a particular plant grew fine until they added CO2, but it is unlikely that the only thing that changed was the addition of CO2. Normally they added more light or did some other things that changes the distribution of CO2. In any case, even if all you did was to add CO2, once a plant becomes accustomed to a certain CO2 level then you have to maintain that level or higher, otherwise it suffers. AS it grows, it needs more CO2. More growth in the tank normally causes more blockage, so there are a few different things going on when you add CO2.

Cheers,

 

[scottward]

No, I really do mean deficiency. H. polysperma has to be the least fussy of all plants, but because of the intense growth rate it often runs out of CO2 before the other plants do. If you had a stability issue then the problem would most likely show up as BBA, not melting/falling. Melting and falling leaves in any plant is due to poor CO2 at the location where the leaves are falling or melting.

Hi Ceg,

Not trying to be argumentative, but I actually think differently.

If the level of CO2 was lower than the plants demand, i.e. not 'non-limiting', but was nevertheless stable, I think the plant would stunt, but I don't think it would melt.

On the other hand, if the level of CO2 isn't stable, this is going to cause serious problems; the plant will be trying to 'adapt' to the level of CO2, but because it keeps changing, the plant keeps expending energy trying to 'tune in' to a moving target. The OP mentioned that the cuttings are disentegrating - this will be because the cuttings are trying to adapt to CO2 fluctuations and establish roots; the plant 'gives up'.

I'm pretty sure Tom Barr will agree with me on this one.

I think because H.Polysperma is such a fast growing glutton of a plant, it's more sensitive to the fluctuations, where other plants, less glutonous plants, can somewhat wear the bumpy ride....

Just my thoughts. Discussion welcome..........

Scott.

 

[Mr P]

Hi folks, i have hygrophila polysperma in my 175 ltr tank,i have 2x24watt T5phillips865 bulbs,the plant grows like crazy,i trim it every 2 weeks by which stage it is usally blocking the light for other plants,i have noticed that where the water flow misses the plant i get deformed growth,i have my diffuser under the filter inlet it has been the best method for co2 distribution ihave used.i cut handfulls of this plant out of my tank.,all the best ,skankypup