Loss of CAL/KH

[reef]

Layton does skimming reduce CAL/KH?

[davidb]

um i'm not layton but i don't think it does no...

[lduncan]

If you mean does it remove unbound Ca++, CO3-- and HCO3- ions selectively, depends on how technical you want to get. But quick answer is not significant amounts.

But it all depends on what the ions are physically associated with in the water, something i'm aware of, but don't know the details of in saltwater for these ions.

[dude]

wow that had out, layton knows so much, are you a marine biologist or something lol

[Jeroen]

Reef,

Take some water of the skimmer and see if the Calcium is much higher then that of the aquarium itself. (can do the same for carbonate).

Cheers,

Jeroen

[reef]

i did this that hench my question.

my tank calicum level was 350ppm and coming out of my calcium reactor it was 210ppm

[wasp]

That's pretty weird!

I'd be interested if the explanation was ever discovered. Perhaps the chemistry forum on RC?

[lduncan]

layton knows so much, are you a marine biologist or something lol

Nope, no specific qualifications. I'm a professional engineer (solid practical science background), I've always had an irresistible urge to find out exactly how stuff works. I read a lot, and think a lot about stuff i'm interested in. The single most important thing I've learnt from this is that knowing your own ignorance's is equally as important as what you know. I think people would be surprised (possibly disturbed) where my interest in chemistry comes from :lol:.

i did this that hench my question.

my tank calicum level was 350ppm and coming out of my calcium reactor it was 210ppm

Remember that the results of these tests kits may be skewed by other interfering chemicals which can concentrate in skimmate. Potentially rendering the results useless. Test kits are developed taking into account the properties and constituents of saltwater and are not necessarily valid for skimmate. If you want a true measure of the calcium concentration in skimmate you'd probably need to look at lab testing using some mass spectroscopy method.

Whether something is skimmable depends on the hydrophobic / hydrophillic nature of the molecule, but in many solutions you don't necessarily find ions like Na+ and Ca++ in pure isolation, sometimes they are associated with other molecules, sometimes water, sometimes organics, not as a true molecule or ion but as kind of a complex ion. These associations may make a particular ion more skimmable, or may make it less skimmable. Like I said i'm aware of the general concept, but not the specifics for these ions in seawater. But I suspect the effect if any is fairly trivial in the scheme of things

So for all intents and purposes, i'd say Ca++ is not skimmed preferentially, and should show in skimmate roughly in proportion to it's concentration in seawater, taking into account evaporation and other factors.

[wasp]

Like I said i'm aware of the general concept, but not the specifics for these ions in seawater. But I suspect the effect if any is fairly trivial in the scheme of things

I'd go with that also.

In fact i'd say there will be an effect, but it will be trivial.

Not so sure that the test kit results could be explained away purely on the basis that the kit is skewed to consider other elements in seawater. Would still be interested to see input from RC Chemistry Forum on this.

[lduncan]

Not so sure that the test kit results could be explained away purely on the basis that the kit is skewed to consider other elements in seawater.

We'll if you think about it, skimmate is going to concentrate particular ions, when you get an increase in ions, you can run into Ksp troubles --> precipitation of stuff.

There are a number of calcium salts which aren't particularly soluble, then considering that calcium itself is already super saturated in seawater, you might also get some organic chelates forming from the increased concentration or organics in skimmate, I could see how it could easily lead to a lot of aboitic precipitation, which would show as a low reading on a test kit.

pH may also be a factor? Dunno how sensitive the calcium EDTA method is to pH though.

For the alk test, there are a lot of assumptions made on where the buffering capacity comes from in saltwater. It's assumed that it more of less comes from carbonate / bicarbonate. But in skimmate it's more likely to come from organic acids some of which will be very skimmable.

The alk test is just an acid base titration, it's not actually looking specifically for carbonate and bicarbonate ions. So it's easy to trick.

Layton

[wasp]

Fair point, you may well be correct.

But remember, we are not talking about skimmate.

Reef mentioned what was coming out of his calcium reactor. Which is why i found it so strange.

[lduncan]

I thought the calcium reactor comment was just a mistake. I assume he really means the skimmer? from the first post:

does skimming reduce CAL/KH?

[wasp]

True. Might have been a typo.

[reef]

its my calcium reactor. the co2 goes into a venturi thus causing bubbles.

All schuran reactors work this way

[wasp]

So you have less calcium coming out, than what's going in?

[lduncan]

So it's both a skimmer and a reactor :lol: hmm, nothing specific comes to mind. But i'd still suspect something interfering with the test method, rather than the actual calcium levels dropping after going through the reactor.

What's the pH in the reactor?