lduncan

Bacteria don't rely on sand for anything. They may go on to lead perfectly normal lives without it. But basically bacteria are very efficient. You don't need anywhere near as much as you think to get the job done. Anymore is just more bioload. They coat every surface in the tank, every crevice in every rock. There is no shortage of places for them to live. The fact that you nuke a few in the water is completely insignificant, they could just as easily get skimmed anyway. There was a study done which showed that while using UV reduces populations of water borne bacteria, it can actually boost the total population by increasing other types by providing more efficient food sources which result from the chemical bonds the UV breaks in larger organic molecules. From memory they were actually looking at some of the same bacteria (P. denitrificans) which perform de-nitrification in our tanks. Pretty interesting. Layton

I don't live here cracker Got more productive things to do. Absolutely, it's the whole point. A bit of debate, to get people thinking, and reading, hopefully from a variety of different sources. Even the DSB advocates agree with that. It's just plain fact. Common knowledge. Chitin is not digestible by most animals, including coral polyps. If you want to do some searching on corals in particular, you should have access to all the papers you want through the university library website. Search for work by Sorokin, he's done a fair bit on coral feeding, metabolic rates and related stuff from the late 70's through to early 90's. I only have access to abstracts, now I'm no longer enrolled. Well apart from the whole subduction and plate tectonics aspects they are surprisingly similar in tanks as they are in nature. It's just that some people think that when you put them in tanks, only the desirable aspects come, and the undesirable ones magically don't happen. Or that you can stop all those undesirable things happening by using critters. A lot of hobby writing doesn't explain how they really work in nature. It was a couple of inches of fine river sand in a remote type setup it was using it to reduce nitrates to zero (They had been around 5 for several months after I moved the tank). It served it's purpose as far as the nitrates went. But it's started to turn bad, I had a couple of rocks embedded in the sand, and could tell that as soon as they started to grow a little hair algae, the bed had gone from a storage cycle to a release cycle. So I just dumped it. Then I found that UV is actually a far more effective solution to reducing nitrate and boosting useful bacterial populations. Without the side-effects of other methods. Layton

It's not garbage at all. It's fundamental. If you don't agree with that, then you're not looking at things logically. 1. Do you need sand to decay the detritus? No. Were does this detritus come from initially. The food YOU put into the tank. The sand bed isn't putting any additional food into the tank. 2. Do corals require critters to live? No. Are critters the most nutritious form of food, considering they eat more nutritious coral food? No. Do you need sand for bacteria to decay detritus? No. Doesn't a lot of this food just accumulate in the sand bed, with only a portion even getting anywhere near a coral polyp? Yes. 3. Do you need sand release the nutrients from the food you feed? No. Still don't see anything which supports the theory that adding sand is more beneficial to corals than no sand. Layton

Please persist wasp, you don't answer many of my questions. So lay out you thinking in a single post from start to finish. I'm giving you a chance to teach me something here. Layton

That's a cop out wasp. Break it down for me in a single post, right from the start the way you see it. How can having sand in a tank be more beneficial corals than not having sand? Simple request. You say you've already done it in this thread more or less. Put it all in a single logical post for me. Layton

I've read it all, nothing even comes close to suggesting that sandbeds are somehow more beneficial to corals, than not having sand. Like I said before. Spell it out for me. Go back and re read the very first post. Then provide me with something similar which shows how sand beds are more beneficial, than having no sand. Cause at the moment, I just don't see it. Layton

It's not about one way being right and the other being wrong. It's about the reasons, logic and justifications behind the choice of doing something one way being right or wrong. I think it's an important discussion.

I went into detail. How about you start from the start and explain to me, as if I knew nothing, how sand is more beneficial to corals, than the alternative, which is no sand? Because nothing you have come up with so far suggests that. Layton

How about we look at it from the other side. How does adding sand benefit corals?

That's not really what i'm getting at. We know corals use them as a food source. But that casing has to come from somewhere. I comes at the expense of the nutritious coral food that the critter was eating. Same thing as above. It takes longer to digest longer for the coral to do this and therefore takes more energy. You have to compare apples with apples here. 1kg of bacterial food, is going to be more nutritious hands down, than 1kg of critters. And if all your putting in a tank is 1kg of food, it's going to best serve the corals in the form of bacteria, rather than bacteria and critters. No, that implies that the DSB is fed more than the BB, that doesn't have to be the case. Stats never lie Look at it a little more closely and you'll see why it's not particularly surprising that that's the case. If you think the corals aren't getting enough food, why not just put more food in your tank? Been there done that. It's not a solution to feeding. Plus there are all sorts of other things you have to worry about with sand.

wasp, do corals need to eat these critters to survive?

Yes the fact that they're crap, combined with the fact that hydrometers are calibrated at a set temperature, 25 C will produce a reading which is way off, especially when the temperature is different from it's calibration temperature. However if the water is colder than 25 C I would expect that the hydrometer would read higher salinity as it would be more dense? The refractometers worth buying have automatic temperature compensation (ATC), which adjusts for temperature.

What are the things which make food available to phytoplankton?

That's not the whole answer. Do you think that a tank with a sand bed will produce less phytoplankton, than one without? Layton

And it's that sand which makes the difference? How so?

It is too simplistic, and it's not a fact that sand beds don't produce phytoplankton. They do. Really. I don't feed my tank? I guess I should find some food to go with that half a sheet of nori, a couple of cocktail shrimp, and a cube or two of brineshrimp I put in the tank everyday. Layton

Too simplistic. What specifically do they use, and where does that come from specifically? Layton

How about we boil this whole thing down to what matters. If you want to feed your corals more. Physically put more food in your tank. Don't pretend that by adding sand you are somehow providing more food for your corals or enhancing the nutritional value of it. You're not. If anything it makes it less available. If you're going to have sand in you're tank, AND feel the need to justify why, at least come up with reasons which are true. Some examples might be as, "i find critters interesting" or "i like the look of sand" or something like that. That's all. Sand isn't a solution or aid in feeding corals. Layton

Is it really a fact that sand beds don't generate phytoplankton? Where do phytoplankton get the nutrients? Layton

Zooplankton isn't the only food for them in nature. It's not always around. It's presence is cyclic, they need other methods. They have multiple sources of food in nature: And each of these sources have different nutritional value. So why the HUGE focus on zooplankton, which is just ONE of several methods? Especially when they actually eat (compete) one of the other (which also happens to be one of the most nutritious) sources of coral food? Which is also the most ubiquitous coral food. ALL corals can eat bacteria. Layton

Made that statement I mean. Not asked that question.

It's not temper. It's the truth. If you did understand more, you wouldn't have asked that question. But i'll persist...

Oh God. This is going to be long! I really don't think you understand enough of this wasp. So where do phytoplankton get the nutrients from?

The polyp may ingest it. It doesn't necessarily have the ability to assimilate it. That's the whole point of excrement, to remove indigestible stuff. Not all food has the same nutritional value. Just because the coral grabs it doesn't mean it uses it, it could just get crapped out again.

The quotes are directly from Dr Ron himself. The bulk of his writing points to one thing, then in the conclusion he promotes the opposite. It's weird. Exactly. Because they are MUCH better. It's the reason why it took so long for researches to prove that corals actually ate bacteria. They are digested so quickly, that by the time that they collected them and got them to labs, the bacteria were beyond recognition, while the zooplankton was all that they could identify from gut analysis. Are you saying that bacteria and critters have the same nutritional value? Can you quantify "excellent"? Bacteria usually have prokaryotic cell walls. (Some have other substances during dormant cyst stages, few can produce chitin). But the fact remains that they are easier to digest, and provide far more nutrition for the coral energy expended. So critters with their chitin casings ARE worse. There is no denying it. Are you comparing fish to a coral polyp? Different animals have developed different methods of dealing with digestion of different things. For example teeth. Animals use them mechanically break these compounds so that the gut has easier access to the useful stuff. Coral polyps are not all the same, different species have different abilities to process different stuff. You seem to be implying that all food has the same nutritional value. It doesn't. Care to elaborate?