Philosophos

Spore germination signaling is definitely still a possibility; it's something with less information on it that I haven't read in-depth quite so much. It's Tom Barr's favored hypothesis right now that I believe he plans on testing it.

If you've been paying attention to what I've said, the cuticle is a waxy compound that often contains allelopathic chemicals; no need to suspend into the water. Even if it does end up in the water, there's something called the barrier zone on leaves that creates a dead water zone, and it takes some decent current to defeat it meaning that the allelochemicals wouldn't be distributed into the rest of the column at the same rate.

-Philosophos

Dustymac

I can't wait!

Oh yeah, I saw the book neither of us read. Wasn't it about terrestrial plants? And weren't the microorganisms they referred to in Chapters 11 and 12 aerial bacteria and fungi? Unlike bacteria and fungi, algae don't interact with the plant leaf. They aren't trying to invade the plant or use it as a food source. Algae simply want something to anchor to and grow.

And how exactly does this work? Leaf surfaces can be pretty bumpy, creating lots of turbulence. Are you saying the chemicals are prevented from diffusing? Now, if some allelochemicals weren't easily water soluble and/or a tad viscous, perhaps that would explain why some plant species seem immune to some algae. Their allelochemicals could ooze to the leaf surface and lay there, inhibiting spore adhesion. Hmmmm...

Or it could be simply a matter of texture and have nothing to do with toxins on the leaf. Some plant leaves could be craggier, snagging the floating spore long enough for the algae glue to be secreted and harden on the plant surface. And other surfaces could be so smooth the algae spores just slide right off. Hmmmmm....

I still like my nutrient depletion theory better and unlike yours, mine is ridiculously easy to test. The procedure is simple: set up two identical NPTs - same substrate, same plants, same lighting, same circulation,˙ same fauna, etc - and hope they both host a mostly simultaneous algae outbreak. Add CO2 to one of the tanks and see what happens. If the algae disappears faster in the CO2 infused tank than in the non-CO2 tank, my theory is correct. It's the only conclusion. If both tanks clear up at the same time, then adding CO2 to inhibit algae is pointless. The only way adding CO2 would be recommended is if the non-CO2 tank didn't clear up and maintained a significant algae presence long after the CO2 tank has cleared.

But do we really need to test my theory? Aren't it's conclusions born out with every new NPT which experiences an algae phase and survives without pumping CO2? And it can't be cuticle allelopathy when algae disappears from rocks, substrate and glass where no cuticle can be found. The only explanations for such algal disappearances are either a tank-wide buildup of allelochemicals, which you deny, or the depletion of an essential nutrient (my theory), which you also deny. How do you explain why algae stops growing on non-plant surfaces?

Jim

DVS

How do you explain why EI, PPS tanks are so successful? If you can resurrect the nutrient limitation hypothesis from the dead, kudos.

Philosophos

Actually I've read large chunks of it; it's been very educational.

Yes, but the same applies to aquatics despite the reduced cuticle

Yes, and this brings it right into contact with the cuticle which brings everything I've been talking to into effect from the barrier zone to allelopathy.

Suspension into a solution may be slowed, but it's the distribution that's reduced as well. As I've said before, many species of plant secrete allelochemicals as a constituent of the cuticle its self.

On the scale we're talking about, I'm not sure it'd matter given the cuticle.

Are you saying it's more likely because it's easier to test?

Why an NPT? Why not control the variables by dosing the column with one species of plant at a time? Why not introduce cultures of algae rather than just hoping for the best?

It's definitely not the only conclusion... I'm not sure how you could think that it would be. What about indirect influences through indirect means related to better plant growth because of limiting CO2 levels? Algae have a far lower requirement for carbon to create the equivalent biomass. What about spore germination signaling? Is the level of CO2 limiting without CO2 given the level of light and other nutrients?

Well yes, then you'd have a balanced tank; one with low light. Unfortunately, getting necessary spread to do everything you want within a planted tank may require more than low lighting levels throughout its entirety.

What about plants with higher CO2 demands? What about the aesthetic of higher light levels, and the CO2 demands they create? What about increased plant growth due to lowered demands for chemicals related to the carbon uptake and fixation process?

You're now creating a straw man out of my statements. I distinctly said earlier that adding CO2 is not necessary for a healthy tank. What I did say is that the light levels correlating with it may not allow for good distribution, and that plants with higher CO2 demands will not be successful features of this tank.

I'd love to see where algae suddenly disappears from substrates without running through its life cycle, under stable conditions. We already know that increasing PO4 will slow the growth of GSA greatly, and this is exactly the opposite of your nutrient depletion theory. Also once again, this is something that spore germination signaling may contribute to.

But that's just it; there are no well studied cases in which allelochemicals have been proven to build up to high enough levels within the aquarium to prevent algae that I am aware of. It's one thing to introduce these chemicals artificially, but where does the release occur? How would it occur if I pull 50% water changes weekly? What about 50% every other day? I've done this, and every point inbetween letting a tank sit for months, so has a vast portion of the hobby. Some how algae doesn't just happen immediately anywhere along the line.

Algae can be limited simply by creating non-advantageous conditions for it, and this does not necessarily mean nutrient limitation. If anything, nutrient limitation has been beaten into the ground repeatedly throughout the hobby as a method of algae limitation. How is it that so many of us have thrown gobs of micro and macronutrients at our tanks without ever seeing algae? How is it that Tom Barr has worked through trying to induce algae through nonlimiting nutrient levels and never done it? Why is it that every test on a macrophyte involving a modified Hogueland solution doesn't run rampant with algae immediately from nonlimiting nutrients being maintained for sometimes months at a time? There is a vast body of evidence contradicting your theory that you aren't addressing.

-Philosophos

Dustymac

Any tank, hi-tech or low can exist without algae problems if an essential limiting nutrient has been exhausted. In "Ecology of the Planted Aquarium", Diana Walstad makes a strong argument that limiting nutrient is commonly Iron. Since algae get all their nutrition from the water, and successful planted tanks are setup with an Iron-rich substrate, it's easy to see how keeping Iron from the water column is all you need do to have an algae-free tank. The plants get their Iron from the substrate and the algae is out of luck.

You can add all the other nutrients you want and it won't encourage algae growth if just one essential nutrient is missing from the water; the algae cannot grow. Voilà!

Jim

DVS

But with EI, and PPS all nutrients macro and minor are being dosed regularly to excess. And properly managed EI and PPS tanks are successful with inert substrates such as sand.

Dustymac

Phil,
I'm back on my iPhone for the next few days so most of your response will have to wait. But you're right about the experiment; it can be improved. How about we start with one tank? We plant both sides so they're mirrors of the other. A couple Swords, a few sprigs of Ludwigia Repens, some Vals. They can even be weighed before planting so neither side has an advantage. Since it's one tank with the same light source, same substrate and same water; there's no chance of having more than one independent variable. Then, after the algae gets a solid foothold, a divider is inserted to break the tank into two identical ecosystems. One side gets CO2 and the other doesn't.

Of course, it has to be an NPT as the whole point of this discussion is to demonstrate how unnecessary CO2 injection is for a well-balanced, naturally planted tank. Just so everyone knows, CO2 injection is absolutely necessary for a hi-tech tank to increase the metabolic rate where plants can utilize all that extra light and nutrition. Without CO2, the hi-tech tank is an algae accident waiting to happen.

Jim

Philosophos

I'll keep thing short so you don't have to come back to a series of nasty text walls. We can get more in-depth with things later.

I'm definitely not saying CO2 is a requirement of all healthy tanks, and I'm sure I never said that it was. I run more tanks without CO2 than with right now, and I'm getting healthy growth with the appropriate species. What I am finding is that you can't keep any species you want under low tech conditions; NPT or otherwise. You can't keep certain fish as well; NPT discus isn't such a great idea. From an aesthetic standpoint, you can't go high light with low CO2 and expect the same results either; some of us want lots of plant growth, or a certain aesthetic to our tanks.

-Philosophos

Dustymac

Phil,
Thanks for the kind tolerance. It's the dang quote brackets; they're three layers deep on the keyboard and you can't scroll in text boxes....sigh.

My problem is I've been doing this for a long time. Back when I was a kid, I used to breed Angels for the lfs. Whenever making a delivery I used to drool over the owner's Blue Discus. When asked about trying them, the owner always told me, "You don't want to do Discus, Discus are hard." That was nearly forty years ago.

I have books on aquarium keeping that go back fifty years. Each and every one of them is replete with false information. I call these tidbits of errata "myths". My favorite one surrounds water changing. With the exception of Diana's book, they all recommend changing 20% of your tank water every week. It's like the hobby's sacred ritual and the water bucket is it's Holy Grail. For want of someone with half a brain taking two minutes to really think about it, literally millions of gallons of water have been wasted.

To illustrate what I mean, let's suppose we have an aquarium which produces a given amount of unwanted waste every week. For kicks, let's quantify this waste by calling it 100 pollution units. This can be anything: excess ammonia, hydroxyl ions or flagelating algae spores. We just want it out of our tank. When the weekend comes we change 20% of the water leaving us with 80 PUs (pollution units) behind. This would be good except after another week of PU production, when we go to change the water again, there's 180 PUs in the tank and a 20% water change only reduces it to 144. After the third water change we're left with 195.2 PUs, the fourth leaves us with 236, etc. Eventually the water averages 450 PUs, 150 PUs if you change half the water every week, but no one does that.

Fortunately we have filtration - bioballs and activated charcoal - and hopefully they take up the slack. We also learn in "Ecology of the Planted Aquarium how plants and dissolved organic carbon clean tank water. It's not too hard to imagine these filter/cleaners working 20% better, obviating the need for water changing altogether.

So, when someone says Discus don't do well in an NPT, is it true? Forty years of imprinting tells me it is but my gut says it might be another myth. Even if it is true, given the nascent nature of NPTs and the amazing buffer formed by the soil/plant relationship, I can't help but think with a little tweaking NPTs could be a great home for the more exotic plant and fish species.

Jim

Philosophos

20% weekly water changes actually aren't too bad if the fish you're keeping aren't too picky, and the quantities aren't so bad. It becomes about a 50% WC every 3 weeks as an equivalent, so waste can never be higher than twice what 3 weeks will provide.

Estimative Index is based off 50% weekly water changes in its foundations, though that level is meant to be flexible. I keep one tank at 50% weekly, and two others at "when it happens" which means once every month or so. This both keeps organic waste and fertilizer quantities in certain ranges. A unique algorithm can be created for any tank to deal with waste and fertilizer levels in the column.

Now if you want to talk waste, the average US citizen goes through something like 80-100 gallons of water per day. Even on original EI water changing, that's 160-200 gallons worth of high light, high tech tank. A good portion of that waste in my case goes to watering the lawn, the garden, my emersed growth tray, and plants around the house. I also step water down; high tech waste water is just fine for low tech tanks to use for a while.

In terms of time and effort, I can maintain my tanks in perhaps 2-4 hours outside of dosing/feeding time. How much time do we cumulatively spend just typing about tanks in a week?

Juvenile discus require abnormally heavy feeding; the waste builds up far faster than in other tanks. I'd discount juveniles purely because of their unique sensitivity and the bioload that they create.

Now as for adults, that depends:
http://www.aquaticplantcentral.com/f...tml#post502226

I tend to agree with Diana's line of thought here; some discus have hypersensitivities to dissolved organic compounds because of their breeding. Any number of organic soils will provide these dissolved organic compounds, and certain fish will stress in them. Try O. mykiss out in a cold water NPT if you want to push the bounds of keeping sensitive fish.

The observation within the entire hobby of discus keeping indicates that water with less organic waste leads to healthier fish, but the very introduction of the substrate is contrary to this concept. So often people start out with discus and throw a pair into a typical tank, or even a planted tank, and have trouble with them from toxicity. I've seen it happen repeatedly, and I've seen increased water changes fix the problem.

Now as for spawning and hatching out eggs (my goal with most species that I keep) I would say that an NPT isn't going to provide the conditions required for many species of fish to spawn. It's rapid water changes that specifically trigger many species of fish best, and in the case of south american fish it's often clean, acidic water that aids in hatching. I can do this in my EI tanks, but the low techs don't tend to induce spawns very well.

I honestly think it's up to NPT keepers to show an exception or good antithesis at this point; the topic has been tested, and it doesn't seem to work very well in practice. If there were evidence to the contrary, it would definitely have to be examined.

I do have one question; why doesn't NPT win any major aquascaping awards? I have yet to see it happen once, and I think it's as fair a criticism as asking anyone into high light and CO2 why they have to put so much work into their tanks.

-Philosophos