A Little Atempt At Myth Busting

[Dave Spencer]

“Crypts and Amazon swords are heavy root feeders, requiring a nutrient rich substrate, or root tabs”.

All rooted plants can take nutrients from the water column via their leaves, as well as from the substrate via their roots. Whilst a nutrient rich substrate allows for some slack in water column dosing, Crypts etc can easily be grown in an inert substrate, provided there are adequate nutrients in the water column.

“You can tell when plants are non aquatic because they cannot support their own weight out of water”.

Virtually all the plants we use in the hobby can support their own weight out of water. Anybody that buys Tropica plants, or any emersed growth plants for that matter, will know this. I grow plants emersed in a propagator, and they all stand upright.

“Plants outcompete algae for nutrients”.

This cannot possibly be true. EI tanks such as my two are run with excess nutrients 24/7. I have nitrates at 25ppm and phosphates at 4ppm, which means there is plenty left for any algae that may be around, yet the algae doesn`t appear. Virtually all tanks have nutrients at levels far in excess of what algae requires, yet they don`t all have algae.

“Lamps need replacing annually”.

Says who? Lamps need replacing when they don`t work anymore. I have some two year old T8s on a tank and the plants are doing just fine. Light output degradation is not as bad as people appear to make out, and plants will adjust to any changes in the output without any problems. Lamps started by electronic ballasts in particular, as opposed to magnetic ballasts which give a flickered start will have even greater longevity.

“Plants need lamps designed for specific plant growth”.

I wonder what it is that these expensive lamps provide for our plants that others don`t. Light spectrum varies throughout the day due to the aspect of the sun, depth of water, colour of the water, shadows move during the day. There are a myriad of circumstances which alter the spectrum of light received by plants throughout their day, and they adapt with no problems, so just what is the correct type of light for our plants? The type that looks best to our own personal tastes.

Feel free to add your own.

Dave.

 

[baron von bubba]

“Plants outcompete algae for nutrients”.

This cannot possibly be true. EI tanks such as my two are run with excess nutrients 24/7. I have nitrates at 25ppm and phosphates at 4ppm, which means there is plenty left for any algae that may be around, yet the algae doesn`t appear. Virtually all tanks have nutrients at levels far in excess of what algae requires, yet they don`t all have algae.

Feel free to add your own.

Dave.

nice post!

still read very regularly on here that ferts cause algae! :0(
it doesn't help that even the manufactures of plant food say "wont cause algae as contains no phosphates and nitrates" etc

i'm with you tho, my nitrates are probably above 40ppm and phosphates 5ppm + with 3wpg+ and no algae problems.....

one more
PH change is very bad for fish
not true, if the ph change is due to co2 being added/removed
true, if the ph change is caused to a kh change (altho i guess technically the KH change is the bad thing and the accompanying PH change is just a effect of this)

 

[nmonks]

The danger with "myth busting" is replacing one set of myths with another set of myths. The problem lies in the aim of non-scientists to apply universal rules to things. Anyone trained in the sciences will be aware that this is very dangerous, especially with biology.

For example, virtually all aquatic plants contain less lignin and fewer xylem (the cells that provide support) than terrestrial plants. They also have thinner or absent waxy cuticles on the leaves, since water loss isn't an issue. This is something you'd predict. Structures with less value tend to be lost as evolution progresses. So if you take a true aquatic plant, like Vallisneria, that cannot live on land and is never found above the waterline, you will find it doesn't "bust" your "myth" number 3, at all. In fact it fits very nicely at one end of a continuum from terrestrial plants at one end to fully aquatic plants at the other.

But then you'll have things like Cryptocoryne species that are bog or swamp plants through much of their range, and while they certainly have thinner waxy cuticles than plants found in drier habitats, they do at least have enough vascular tissue to support their leaves and stems. So they're somewhere in the middle of the continuum mentioned above.

So, the more fully adapted a plant is to life underwater, then the less able it will be to support its leaves and stems above the waterline. It's not an either/or thing, it's a general trend.

Let's look at your "myth" about root feeders. If you think about that statement for more than a few seconds, you'll understand that this is again a continuum rather than an either/or situation. Floating plants, like Lemna for example, clearly take all their nutrients from the water. Then at the other extreme you have terrestrial plants that get all their nutrients from their roots, their root hairs in particular being the cells capable of active uptake (i.e., the necessary expenditure of energy to pump nutrients from low concentrations outside their cells towards the high concentration of them inside their cells).

Many aquatic plants will be somewhere on this spectrum. Woody aquatic plants, such as Hygrophila corymbosa, will not be able to absorb nutrients through their woody stems, leaving just their leaves. Compared to their roots, their leaves have a thicker waxy cuticle since they're adapted to function above the waterline as well as below it, and so any ability to absorb nutrients will be limited. Such plants will get most of their nutrients via their roots. Non-woody plants though, like Ceratopteris, which have leaves specially adapted to working below the waterline will be able to absorb nutrients from the water column more readily.

How "heavy" they are in terms of mineral nutrient demands will depend on growth rates, what pigments are in the leaves, and so on. Again, this is a spectrum. Slow growing plants like Anubias will obviously use less than fast growing things such as Vallisneria.

There's nothing wrong in arguing against misconceptions. But you have to be very careful about replacing what may well be an outdated misconception with a new but overly broad generalisation.

Cheers, Neale

 

[Dave Spencer]

So, the more fully adapted a plant is to life underwater, then the less able it will be to support its leaves and stems above the waterline. It's not an either/or thing, it's a general trend.

But with so few true aquatic plants, and with barely less than 100% of plants available to us hobbyists being truly aquatic, it is less than a general trend. Barring Vallisneria sp and one or two others, the plants we use in our aquariums can, and do, support their weight out of water. All the Rotala sp, Ludwigia arcuata, Hemianthus micranthemoides, Staurogyne sp I propogate stand upright. Their physiology obviously changes in the propogator, but they are the same species, and they stand upright. The physiology of stem plants in particular changes when emersed, but many of us buy our plants in this state.

Fair enough Neale, true aquatic plants can`t support their own weight out of water, but outside Vallisneria sp their is, arguably, nothing else generally available to the hobbyist to refute what I have said. You are a scientist Neale (I think), but this is not a science forum, and the semantics of one mainstream species of plant refuting my attempt to rid the planted tank of the "aquatic plants can`t support their own weight out of water" statement hardly means that the scales could swing either way on this. The plants available to us are overwhelmingly semi aquatic, with the ability to support their own weight out of water.

Let's look at your "myth" about root feeders.......

Many aquatic plants will be somewhere on this spectrum. Woody aquatic plants, such as Hygrophila corymbosa, will not be able to absorb nutrients through their woody stems, leaving just their leaves. Compared to their roots, their leaves have a thicker waxy cuticle since they're adapted to function above the waterline as well as below it, and so any ability to absorb nutrients will be limited. Such plants will get most of their nutrients via their roots. Non-woody plants though, like Ceratopteris, which have leaves specially adapted to working below the waterline will be able to absorb nutrients from the water column more readily.

This was generally aimed at people who insist that Crypts must either have a nutrient rich substrate, or root tabs for them to thrive. I, and many other hobbyists have proved this to be totally incorrect by growing healthy Crypts in an inert substrate, but provide sufficient nutrients in the water column. Moving on to Hygrophila corymbosis, I would be tempted to agree with what you are saying, but after initially struggling with Hygrophila corymbosa "Siamensis" 53B in inert gravel with an EI dosed water column, it`s current growth would refute what you are saying. Personally, I have proven to myself that I no longer need to spend money on a nutrient rich or high CEC substrate, irrespective of what plants I buy or propogate.

There's nothing wrong in arguing against misconceptions. But you have to be very careful about replacing what may well be an outdated misconception with a new but overly broad generalisation.

Cheers, Neale

I could have mentioned the exception of Vallisneria sp, but I feel there are no generalisations in this thread. We can all prove anything on this thread to ourselves via empirical means, independently of what any science may wish to say. Other than saying "virtually all...." regarding aquatic plants, instead of semi or true aquatic, there are no generalisations.

Dave.

 

[nmonks]

But with so few true aquatic plants, and with barely less than 100% of plants available to us hobbyists being truly aquatic, it is less than a general trend.

There are plenty of other true aquatics in the trade. Elodea, Cabomba, Potamogeton to name but three genera.

You are a scientist Neale (I think), but this is not a science forum, and the semantics of one mainstream species of plant refuting my attempt to rid the planted tank of the "aquatic plants can`t support their own weight out of water" statement hardly means that the scales could swing either way on this. The plants available to us are overwhelmingly semi aquatic, with the ability to support their own weight out of water.

I think you're missing my point. I'm not saying some aquarium plants can't support their weight out of water, but rather than the degree to which they can reflects how well adapted they are to the aquatic lifestyle.

Moving on to Hygrophila corymbosis, I would be tempted to agree with what you are saying, but after initially struggling with Hygrophila corymbosa "Siamensis" 53B in inert gravel with an EI dosed water column, it`s current growth would refute what you are saying. Personally, I have proven to myself that I no longer need to spend money on a nutrient rich or high CEC substrate, irrespective of what plants I buy or propogate.

You see, this isn't science. Your explanation is merely one of multiple possible hypotheses. Let's raise an alternative. Initially, the plants didn't grow because the gravel was inert and nutrient free, but over time, organic decay and mineral nutrients accumulated in the gravel, until a threshold was reached where the plants were able to grow. There's ample evidence that plant roots need do culture microbes around their roots for nutrient uptake to occur properly. So it can take transplanted plants a while to become established. I'm not saying that's what happened, but rather what you're saying happened isn't an explanation that meets scientific ideas of rigour.

The point with growing plants is that there are clearly lots of different ways to do it. Each method has its pros and cons, and I dare-say each method has its advocates and critics. I've seen fantastic low-tech planted aquaria, and rubbish Amano-style high-tech ones. Aquarists would do well to read around the topic, experiment themselves, and read a little botany if they want to appreciate what's going on.

Cheers, Neale

 

[Dave Spencer]

You see, this isn't science.

I didn`t say it was, Neale. It is observation.

Your explanation is merely one of multiple possible hypotheses. Let's raise an alternative. Initially, the plants didn't grow because the gravel was inert and nutrient free, but over time, organic decay and mineral nutrients accumulated in the gravel, until a threshold was reached where the plants were able to grow.

You see, this isn`t science.....but then you never said it was.

Running planted tanks is an empirical process that most people can carry out. This hobby is not a science, so let us not try to make it so.

Hopefully, people will read this thread and realise they do not have to fork out on ADA Aqua Soil, or expensive plant specific lamps.

Dave.

 

[nmonks]

I didn`t say it was, Neale. It is observation.

Fair enough. Observations are good. Science is based on observations. But when extrapolating outwards, you need to be careful how you present your *interpretation* of those observations.

Hopefully, people will read this thread and realise they do not have to fork out on ADA Aqua Soil, or expensive plant specific lamps.

Now that I do agree with. I'm very low-tech, and yet my plants tend to do rather well. My aquaria are messy-looking, yes, but the plants are happy!

Cheers, Neale

 

[SuperColey1]

I agree with Dave and I guess in a way I agree with Neale

However I've given up myth busting at least for a while because too many people seem to want to believe the myths and/or believe they are truth

The truth is always out there but far too many are too blind or stubborn to find the truth.

Light is the main bane in my eyes. Certain forums including one of the biggest 'planted' ones still bang on about spectrums, high light, Lumens etc. they don't want to listen so let them spend fortunes on equipment, electricity and then on all the extras they need to manage their turbo system. Most of them start to beg for answers pretty soon afterwards which lets me chuckle and say 'read my post on page 1'

AC

 

[Truck]

no plant needs more than 2WPG, although some are insistent on this! 1.5WPG of T8 will grow anything IME as long as CO2 and fertilization is good.

Silicates do not cause brown algae ammonia does. i know these are basic, but i thought i would add me tuppence.

 

[jonp]

Regarding the lamp changing - Annually may be excessive, but the gases in all tube/energy saving type lights change over time and after two years will be using more than 30% extra energy than when new. I did some research(well OK googling) on this recently and as such my employers have just replaced every bulb in our office spaces.

 

[aaronnorth]

“Plants outcompete algae for nutrients”.

This cannot possibly be true. EI tanks such as my two are run with excess nutrients 24/7. I have nitrates at 25ppm and phosphates at 4ppm, which means there is plenty left for any algae that may be around, yet the algae doesn`t appear. Virtually all tanks have nutrients at levels far in excess of what algae requires, yet they don`t all have algae.

Someone linked a paper to me the other day claiming N&P cause algae, and those levels were something daft like 0.2micrograms lol, so it shows limiting nutrients so algae doesnt get a chance is impossible.


substrate heaters help with plant growth

If they do then the improvements must be extremely small. Take a look at all the beautiful planted tanks you see out there, and i can almost gurantee only about 5% will use one

 

[Nick16]

with regard to the specific plant growth tubes. i was talking to the guy who works at lampspecs and he said that he used to work for GE, and said they used to supply companies like interpet with tubes that they sold for around £4, interpet were selling them as special plant growth ones at £12-£15, so there is some truth there that you can buy a non plant growth tube and it might actually be the same thing. For me its all about getting the colour right, i like a mix of sylvania's grolux and osram's lumilux tubes.

 

[nmonks]

You see, this isn't science either.

If I go for a walk by the beach and fail to see any sea lions, it doesn't mean sea lions don't exist. Likewise, if you see planted aquarium that work, and they don't contain substrate heaters, that doesn't mean substrate heaters aren't helpful.

For your argument here to be scientific, you'd need to set up a bunch of identical tanks with the same species of plants (ideally, cuttings from the same parent plant to zero out genetic variation). You'd run the tanks, and then compare plant growth. So far as I know, that hasn't been done, though the proponents of substrate heaters (like the authors of The Optimal Aquarium) may well have done such experiments.

I'm perhaps labouring the point that there's a difference between science and opinion, but that's the A-level biology teacher in me coming out. I'm all for informed opinions, and voice lots of them myself! But if we're going to talk about "myth busting", then the idea is to replace ideas that are demonstrably wrong with reliable, verified facts.

For what it's worth, I used substrate heaters from the 80s to early 90s in my planted tanks, and they seemed to work perfectly well. Whether they were better than other types of heater in terms of plant growth I cannot say, but they do have other advantages besides that.

Cheers, Neale

substrate heaters help with plant growth
If they do then the improvements must be extremely small. Take a look at all the beautiful planted tanks you see out there, and i can almost gurantee only about 5% will use one

 

[Dave Spencer]

For your argument here to be scientific, you'd need to set up a bunch of identical tanks with the same species of plants (ideally, cuttings from the same parent plant to zero out genetic variation). You'd run the tanks, and then compare plant growth. So far as I know, that hasn't been done, though the proponents of substrate heaters (like the authors of The Optimal Aquarium) may well have done such experiments.

How about running a tank with a cable heater for six months, then switching it off? I have, and there was no difference in growth. I have never used one in a tank since, and never will again. It comes in handy in my propogator for keeping the humidity up, so it wasn`t a total waste of money.

For what it's worth, I used substrate heaters from the 80s to early 90s in my planted tanks, and they seemed to work perfectly well. Whether they were better than other types of heater in terms of plant growth I cannot say, but they do have other advantages besides that.

What benefits did you see, Neale?

I believe you will soon be carving a very lonely furrow in the planted tank world, Neale. Times are moving, people are watching developments in their tanks more closely. Scientific proof is irrelevant among the deluge of empirical evidence. The tired old nutrient/algae arguments, plus many others are dead amongst the upper echelons of planted tanks (with the notable exception of Amano).

Dave.

 

[aaronnorth]

Likewise, if you see planted aquarium that work, and they don't contain substrate heaters, that doesn't mean substrate heaters aren't helpful.

I never said they werent helpful, i just said they dont help as much as some people make out. Some people are adimant to run a succesful planted tank you need a heater cable when it isnt true. So if you dont need one, then i dont see the point in buying one, it is extra cost that is unecassary for the small improvements they bring...

For your argument here to be scientific, you'd need to set up a bunch of identical tanks with the same species of plants (ideally, cuttings from the same parent plant to zero out genetic variation). You'd run the tanks, and then compare plant growth. So far as I know, that hasn't been done, though the proponents of substrate heaters (like the authors of The Optimal Aquarium) may well have done such experiments.

....ok that isnt scientific i agree, but i can show lots of examples of good, healthy plant growth without the use if substrate heaters, if i compared a plant out of a non-substrate heated plant tank with a substrate-heated planted tank, i bet you wouldnt be able to see any difference at all. And that is my point, they simply cant improve plant health when it is already optimum,

i can give you an example if you like lol.

Whether they were better than other types of heater in terms of plant growth I cannot say, but they do have other advantages besides that.

I do realise they have other advantages, but i thought i would stick to plant health here.

Thanks, Aaron