lduncan

But there is a increase in the steady state waste concentration in your example. It increases by 5%. The skimmer output can only increase 5% if the waste concentration has also increased by 5%. Which means that there has been a build up of waste. Remember the waste the skimmer pulls out is proportional to the concentration of the waste in the water. Layton

What? You obviously just misunderstood the context of it. Not misinformation at all.

Pies was inferring that those links were just random pages from zeovit.com, and that I was hoping no one would actually read them. I said that there is a common theme amongst those threads I posted, not necessarily in general. That's all.

True :lol:

http://english.aljazeera.net/NR/exeres/ ... 6C49EC.htm

I do expect people to read them. They are a collection of "user experiences" with zeovit. Read them, and you'll see a common theme. That's false, I followed the original instructions from Mr Pohl himself.

I have not made that assumption at all. Quite the opposite. I've said the skimmer output is proportional to the concentration of waste in the water.

It's not a wide ranging statement at all. It's exactly how it works. What you've said doesn't make sense at all.

How is it high maintenance when setup on dosing pumps? How is it less stable, when setup on dosing pumps?

Hmmm... by that reaction anyone would think I claimed that calcium reactors don't work. I haven't, just that there are easier and less expensive ways than calcium reactors, now that people realise they don't have to buy 2 part in bottles from a shop. Layton

Although there are many ways to skin a cat, there is always one BEST way to do it. The thing is that the BEST way is not necessarily the same for everyone. What I try to do is get to the reason why people want to do something they way they do, then see if it makes sense. Taking the refugium as an example. Putting in a refugium with a primary focus on exporting waste IS wrong. Putting in a refugium because you like watching critters by torch light, sure. Like i've said all along, if your going to add something to your system, know what it does, and do it for the right reasons, don't justify it with flaky or plain wrong reasoning. Layton

... or don't know any better. They're told they need a calcium reactor to keep up with demand from stoney tanks. In reality, if instead of buying a calcium reactor, they bought a couple of dosing pumps, they'd find two part systems easier, and less expensive to run.

I was talking about additional water volume alone, not specifically in the context of a refugium. My point is, the extra water volume does not cancel out the added load from the refugium life. Layton

But it doesn't make a bit of difference in terms of water quality. Sure it's better for keeping chemistry like calcium, magnesium etc stable. But that's it. Layton

Yip, they show up EVERYWHERE, in the natural world. They don't just show up in voltage over a capacitor, and current through an inductor ;-) It's pretty much a standard first order step response.

Nope. Engineers need to know these types of systems inside out. Here's a better one, showing the effect of skimmer output, and waste concentration. The system starts off at 1,000 litres, then changes to 2,000 litres after 20 hours. The flow through the skimmer and waste input is kept constant. It's shows that the steady state waste concentration is independent of total system water volume. Layton

Ok here it is: http://www.nzreefs.com/images/System%20Volume.xls Summary: System 1 = 1,000 Litres System 2 = 2,000 Litres Both have identical skimmers pumping 500 litres an hour, and waste input is constant at 1000 grams per hour. Although the one with more water initially starts off with lower waste concentration, both systems end up with the same concentration of waste in the end: Layton

I don't think you guys get the dynamics which are going on here. I've put together a spread sheet to show you. Give me a second.

The assumption that you are making is that the skimmer pulls the same amount of waste out per unit time, independent of the concentration of waste. That is wrong. The amount of waste the skimmer pulls out is proportional to the concentration of waste. Think of it this way. You put 1,000 gram of waste into a 1,000 litre tank, and 1,000 gram into a 2,000 litre tank. So the first tank has a concentration of 1 gram per litre, the second 0.5 grams per litre. Say the first tank has a skimmer which put through 1,000 litres an hour, and say it removes 100% of the waste going through it. It's going to remove 1,000 grams of waste in an hour of running. Now the second tank has that same skimmer on it (pumping through 1,000 litres as before, removing 100% of the waste passing through it), then it is going to pull out only 500 grams of waste in an hour of running. So extrapolating this through the dynamics of the system, it means that the concentration of waste in the water is independent of the total water volume of the system. It is a function of skimmer parameters.

How? You didn't remove any animals, you didn't reduce feeding. The import of waste is exactly the same as before. How? The output of the skimmer per unit time, is inversely proportional to the concentration of waste in the water.

And for that reason it's called a generalisation, you'll probably find it's a pretty good one. For example the starter of this thread considered macro algae to be part of a refugium. Take a poll of reefkeepers any you'll more than likely find that this is the overwhelming opinion of what a refugium generally consists of. All I said was that nutrient export was not a good reason to have macro algae.

Initially yes, but then because of that concentration drop, the skimmer doesn't pull out as much waste per unit time. Which means that if the input of waste is constant (which it is, because you haven't added or removed animals), the concentration of waste then rises (as the skimmer is removing less, but the input is the same) And eventually you get back where you started, which is the equilibrium point of the concentration of waste and the skimmer. So again, the concentration of waste isn't related to the total system volume, it's related to skimmer parameters. It's the behaviour of a typical dynamic system.

Nope, it doesn't make sense. Concentration is the amount of something per unit volume. If you look at the steady state, then the concentration of waste before and after adding extra water volume is exactly the same (given no change to skimmer parameters). The dynamics will be different, initially the concentration will be lower, but given time to reach equilibrium again, the concentration will return to what it was before the extra volume was there. The physics of the skimmer will ensure this.

Be realistic. You know that when people hear refugium, they think sand, macro, pods etc.

more or less 2 part system that we use here. However the Balling method also takes into account the small changes in chemistry by using sodium chloride free salt. Calcium reactors are history