lduncan

And that the simplified practical approach :lol: . Mathematicians would go nuts if they knew the techniques and approximations engineers use . It's pretty strange that some of the maths we have to know was developed as late as the 60's and 70's ... and but the look of some of it, there must have been drugs involved, there's no way they could have come up with it otherwise :lol:

More engineer than scientist

Most acids are acidic, i think you mean acetic ;-) Where's that edit function when you need it.

Palytoxin: http://en.wikipedia.org/wiki/Palytoxin The antidote is pretty extreme, injecting the heart! It's pretty amazing that they've manage to produce it synthetically too. It's one monster molecule!

It's not an issue of knowing how to use a calcium reactor. Calcium reactors are tuned with a feedback method, and the variables (bubble rate, and drip rate) are a lot more abstracted from the calcium levels and alkalinity levels you're trying to control, than they are when you know exactly how much you're adding as with a two part type system. For example, if you know your tank uses 1 dkH of alk a day, it's pretty difficult to convert that into a bubble count and drip rate, whereas it's pretty trivial to convert that to a volume of 2 part to add. That's my point of view anyway.

Much easier than pissing around tuning calcium reactors

Baking soda and CaCl2 here. 300mL of Randy's Recipie #2 every day in around 1000 Litres. I'd also add strontium every now and then once I find a decent source. Oh and MgCl2 once in a while.

what's in the tank? The phosphate seems really high.

Cool video

The expensive part, as everyone who's looked have found out, is the dosing pumps. They all seem to be for medical uses, with the price tag to match. The cheapest I've found were OEM ones from Autoclaude ( www.autocludepumps.com ), and they were about 29 pounds per pump in quantities of a couple of hundred (50 pounds for samples). If you can manufacture the pump yourself, then you could potentially make it cheaper, but then you're looking at high minimum volume, or massive manual work. Also the synchronous ac motors are not particularly cheap, and if you go with DC, then you generally need a geared system which also soon adds to the cost. I've looked at getting the Grotech system, it looks really good. I guess it works out to be similar price to a decent sized calcium reactor, but it's still a lot of money for what it is. Layton

wasp, are you able to explain why this is wrong? This is what made me ask in the first place. It seemed to contradict what I had heard from elsewhere, and what you had said. What I wanted to know was the truth. That's all. I wasn't saying you were wrong, i was asking a question. The above explanation "seemed" to correspond with Randy's graphs, and it "appeared" that it was correct. And i'm still trying to fully get to grips with what is actually going on in terms of chemical equilibrium. I get it in "general" terms, just not quantitatively. I wasn't arguing, I was trying to understand what's actually going on. If you do fully understand what's going on, i'd be interested in the quantitative analysis of it. The part where these threads go off the rails is where you try and make it personal, claiming you're being victimised. Layton

I would suspect corrosion or salt creep if turning the calibration screw through it's full range doesn't correspond to a sweep of values on the display. If that's the case it may still be fixable.

Wasp you're still trying to drag this down to being a personal thing. It's not. I've posted why I asked the question. Here it is again:

First i'd triple check the calibration fluid is not contaminated. Then check the probe (borrow a known working one to try on your unit), but if it's that far out the probe must really be screwed. If none of that works, then the meter is bung. If nothing is happening at all (not change at all on the screen) when you turn that screw full range, it's more than likely the meter which is screwed (may be fixable though, especially considering the 7 point seems to work). Layton

You know wasp, I was not trying to pass this of fact right from the start. It was a question "are you sure?". Why did I ask the question? Because I had seen this passage: And I wanted to find out if in fact it was correct. I asked you if you could explain it, but there was confusion on what I though, and you thought you were saying. So I wrote some equations. Then asked Randy for his input. He said that the concentration of carbonate is not constant, something which I had missed, but from his graphs it looks as though within a 1 meq range the pH change is pretty close, even when carbonate is factored in. Layton

I've been trying to figure this particular question out. I haven't passed it off as "fact", that's why I asked the question initially. Maybe i've missed something. I'm still unsure, what I said seems to be the case for the ranges of alkalinity tanks run at, from Randy's graph, and the equation.

I got that all the way back on page 2. From what you wrote it seemed like you were saying something else.

Mine drops around 0.8 to 1 dkH every day. That's equivalent to around 13 grams of coral skeleton growth per day, if it all goes into coral growth. KH can drop from precipitation with calcium (or initiated by iron oxide hydroxides), growth of coral skeletons, but bacteria can be a significant consumer, as it is an easy source of carbon.

How time flies! Interesting to see the changes in just two years! I even took a bit of convincing:

Looks like I found the answer. This graph from Randy seems to confirm my thinking above: The red arrows have been added by me. This shows that for typical ranges of alkalinity, a tank with a higher alkalinity (Tank 2 = 3.5) sees the same drop in pH as one with a lower alkalinity (Tank 1 = 2.5) when a certain amount of CO2 is added. So it seems that this isn't correct in the case of CO2. So it's kind of unusual, but at the same time important as CO2 is the acid which often effects this equilibrium, and has potential to skew it. Layton

Do you have anything useful to add?

What you posted makes sense but this is what you said: From what I understand from that, you are saying that if your tank alkalinity is higher than someone else's, then for a given amount of added CO2 you'll get a smaller change in pH (swing was probably the wrong word to use before). That's the part i'm not so sure on when the majority of the buffering in our tanks comes from carbonate / bicarbonate. Here's the reason. The equilibrium equations for the CO2/carbonate/bicarbonate system are: [HCO3(-)] [ H(+)] / [H2CO3) = 10^ -6.3 [CO3(2-)] [ H(+)] / [HCO3(-)] = 10^-10.3 [H2CO3] = 10^-1.5 P(CO2) Rearranging these you get: [H(+)] = 10^-1.5 * 10^-6.3 * 10^-10.3 * P(CO2) / [CO3(2-)] and pH = -log( [H(+)] ) It seems that from this, that although the pH values a different, the change in pH for a given addition of CO2 is independent of the alkalinity. It seems that a higher KH (by adding baking soda) does not reduce the change in pH from CO2 additions, as you would typically expect from a buffer solution. I think it's a condition specific to the carbonate system and CO2, it doesn't work where the buffering capacity is provided by other ions like phosphate or boron. They behave as you have suggested. That's why I asked the question. The passage above doesn't address that. I've asked Randy to have a look over it and see what he thinks.

:roll: Again I never said that. You twisted something I said. What I actually said was: and you response to that was: I don't "zeobash", just ask questions, and note observations. Layton

:roll: I didn't rubbish Mesocosm at all: And despite your persistent mindset I have nothing against anyone who chose to use zeovit, or any other method. I've been pretty patient with some of your snide posts recently so quit playing a victim. Most of the time I'm just asking questions. You always try to make things seem like a personal attack on you or someone else, it's not. Back on topic, guide me to the link that you say will clear this up and i'll read it. If it doesn't clear it up, i'll do some numbers and find out what actually happens. I have a gut feeling that the pH swing will be the same irrespective of what the alkalinity is for this carbonate / bicarbonate / CO2 system.

says above, zoo plankton, so that would be cellular. But shouldn't that be a trade secret? :lol: