lduncan

I think you're confused.

The model is virtually the same as the one I came up with, with the inclusion of a few variable which I had accumulated into the "efficiency factor", and a model of diffusion, which only changes time scales, not the trends and end results. Really the only difference is that the transients are shown a bit better. But the trends and end results are the only things you can take from these models.

Well if you remember, someone claimed that extra volume reduces nutrients by dilution? Which is wrong, it doesn't. Comes back to doing something for valid reasons. If you add more water volume in an attempt to lower nutrients, you're going to be disappointed. If you add more water volume in an attempt to reduce fluctuations in resources like Ca, Mg, HCO3 etc, then you will be happy. Making broad sweeping statements like "big is good" isn't always useful. In this case big isn't necessarily good in terms of nutrient concentrations, it's no change.

Exactly.

Wasp, what you're trying to do is bring in "other factors" which are totally unrelated to increasing water volume. Then attribute any effects from these unrelated changes to the added water volume, when in reality it has nothing to do with water volume. Then in your mind you see the fact that I haven't considered these completely unrelated factors, as the model being narrow. When in reality it's the model modelling exactly what it's suppose to. Layton

So, how does adding water volume, make the amount of rock in a system increase? Better for water quality, or better for livestock health? There is a difference. The confines aren't narrow at all, and it seems I'm not the only one with this opinion. The guy in that link obviously thinks so too. Of course I'm biased because... well by the looks of it, because I don't agree with wasp :-?

Hmm, I should have checked out the web, it would have saved me a lot of typing. The link that Jeroen found pretty much covers what i've been saying: http://www.reefs.org/library/talklog/d_ ... 12499.html Namely, that increasing water volume doesn't change nutrient concentrations. Layton

concentrations stay the same pool totals increase proportionally to the volume of water added

Well when you look at these types of systems there are two analysis you can look at, depending on what's important to you. Either transients, or steady state. Think of it like this, you have a spring with one end fixed to a table, then you give the top of it a flick (this is called an "impulse"), it starts to vibrate. The transient response is what happens throughout the whole time after it has been flicked ie: the motion of the vibration. The steady state, is the state the system tends to after the transients have been and done (the long term effects resulting from the "impulse"). In the example of the spring, the steady state response is that the spring stays in the same position as it was before the impulse ( the flick ). For example in my specific field, transient analysis is important so that components don't overheat and explode, or control systems don't become unstable. But for this discussion here, we're only really interested in the permanent effects of changes, hence the term "steady state". What more do you want? It's kind of self explanatory, isn't it? Adding water doesn't change the levels of these parameters in the steady state. Layton

What's the response of to nitrate / phosphate levels increase system water volume? In the steady state, nothing, they stay at the same level. And trust me, i'm no genius, misunderstood or otherwise. Some people I know, know more about a lot wider variety of things than I do.

Ok, So now we take the same system as before, but increase the waste input 5% to 1,050 g/hr System 2 Skimmer Flow: 1,000 L/hr Waste Input: 1,050 g/hr So doing the same as before, for the concentration of waste to be stable (at equilibrium point, steady state), then the skimmer outpur per hour has to be equal to the waste input per hour: skimmer output = 1,050 g/hr As you can see, the skimmer ouput has increased by 5% in response the the increase in waste input. Now what about the concentration of waste? Has it increase? Well as before, the skimmer output is equal to the flow rate through the skimmer times the concentration of waste in the water: 1,050 g/hr = 1,000 L/hr * Concentration of waste g/L Concentration of waste = 1050/1000 = 1.05 g/L So not only does the skimmer output increase in response to increase in waste input, the concentration of waste in the water also increases proportionally. So now what happens to waste concentrations when you add more water volume to a system? Well, in the stready state, absolutely nothing. Athough intitally there will be a drop in waste concentrations, there is also a corresponding drop in skimmer output, but eventually the concentrations come back to what they were at the beginning, before the extra water was added. The skimmer output and concentration of waste is independant from the total system volume.

Yes, way too high. It needs to be undetectable for optimum long term health of sps, and to keep algae and cyano at bay.

Clown tangs need a lot of food to stay healthy and survive long term. So I would not recommend cutting down feeding. Best to concentrate on exporting more. Also, the nitrate itself isn't too much of a worry, the phosphate will cause more problems.

http://www.advancedaquarist.com/issues/ ... eature.htm The next one isn't directly relevant, as it is talking about temperate anemones, but it briefly mentions some differences between tropical species. And it also references another study of 105 different corals which looks at whether they inherit, or are infected after spawning. http://www.biolbull.org/cgi/content/full/205/1/66#R1

Googled it and found some specifics, and some generalisations. Some common anemones come with starter cultures: And it looks like that in general most tropic corals aquire them after spawing: Either way, it looks like they are all capable of being "re-infected" by suitable clades during their lifetime. Layton

One thing i've been thinking about is why would anemones and corals voluntarily expel one of their major sources of food, zooxanthellae, in times of stress? Surely that's when they need them most. I think it's the zoxanthellae which decide that the grass is greener elsewhere and grow their flagellate parts and go swimming. And the coral / anemone has no choice in it.

I've always read that most corals and anemones inherit zooxanthellae starters from their parents during sexual spawning.

You can't force it to do it. It must be a mutual "agreement" between the host and the zooxanthellae. The host must allow the type of clade you are introducing, and the zooxanthellae must decide whether it want's to live there. The one thing the host has no control over is whether they stay put or not. Coral don't "expel" zoxanthellae, the zooxanthellae decide to get up and leave. Clam propagation is one of the area where zoxanthellae transfer is known to occur. Small clams don't start life with a "starter culture" of zoxanthellae like most corals/anemones, so they must always get it from the water. Clam propagators intentionally kill pretty clams to release those specific clades in an attempt to get the baby clams to host those types, and carry through those colours. So it can work. But just remember if it doesn't want to happen it won't.

Well first things, the anemone doesn't really have a choice in what symbiots it houses. That decision is made by the zooxanthellae. They choose which hosts they "infect". So feeding it zooxanthellae from another anemone is no guarantee that it will transfer them, it may, or may not. There will still be zooxanthellae in the anemone. They will come back given time. However in the mean time, it would be a good idea to feed it meaty foods, so that it doesn't wither away. Layton

Too hard? No. Harder? Yes. There's a difference wasp. Why make life harder than it has to be?

A bumper sticker comes to mind here:

Well it comes back to this post: Which I said was wrong and not a valid point. Then it went from there people saying I was wrong, that water volume diluted nutrients so your tank would be cleaner. Which is all clearly wrong. And a point which some people still can't see. Hence the continuing debate. Simply adding water volume does nothing for lowering nutrients in the steady state. If you can follow what i've been saying, then you'll have a good idea on how to, and how not to, lower nutrient concentrations permanently. Layton

The reasons they are called models is because they ARE based on reality. They model reality. Models can never be hypothetical. Not narrow at all. And yes you will find that this happens in a real tank. So I giving you a chance to say what those variables are. All i'm talking about is adding extra volume to the tank. So what other variables are there? I think you are getting so bogged down with unnecessary detail, that you can't see the forest from the trees. At it's simplest, a tank has a certain input of waste, and a certain output of waste. You don't need to get into the details of how the waste is created etc. Layton

But that doesn't mean waste concentrations have changed. The one think which added volume is good for is there is a larger pool of resources for animals, (think alk, mag, calcium etc), the large pool means that the relative levels change more slowly, and if resource limitation was an issue in the smaller tank, sure, going to a large tank is going to make a difference. BUT what going to a larger system volume does NOT change is the concentration of waste in the water. Sure but it still won't change the concentration of waste in the water. The animals may suffer and die from resource limitation. As parameters like calcium, magnesium, dissolved oxygen etc may drop rapidly, if the aquarist doesn't make sure they are as stable as they were in the larger volume tank. So, again, the concentration of waste in a system is NOT dependant on the volume of water it holds, just the flow through the skimmer, the efficiency, and the input of waste Where is all this going? Well if you understand this, you understand from a skimmer point of view, how to lower the concentration of nutrients in your tank and sustain it. (And just to recap, it can't be done by simply adding water volume) Layton

Wasp i'll try and explain this In engineering, which is REAL WORLD science, when figuring out how something works and how to control it, we use things called "models". Depending on what you're wanting to find out, the model can be detailed and complicated or relatively simple, but you always try to use the simplest model possible which gets the job done. What i've tried to do here is to remove the details of efficiency, and bundle it into a factor called the "efficiency factor" Then because suphew brought it up, we looked at the efficiency factor and found that it is NOT dependant on the total system volume. So then the efficiency doesn't change the outcome i'm trying to show here. The final result is going to be the same, the efficiency may alter how long it takes to get there, but that's it, it doesn't change the final result. That's the reason why I haven't complicated things by including efficiency, and made the assumption, for the sake of simplicity, that it is 100%. Wasp you are dragging in other factors which don't have anything to do with adding water volume. What I'm talking about, is the claim that adding water volume can lower nutrient concentrations in the system on a sustained basis by dilution. It doesn't. In terms of waste concentrations, doubling the volume of water in the system will have no steady state effect on them. Layton