chemistry 101

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cathy

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May 2, 2003
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Over the weekend my LFS checked my water for me, and told me
that my calcium levels were a little low. (360)
They recommended the addition of Calcium chloride in a gradual manner. (Ie, 1/8 tsp granules per 50 gal, dissolved in water, added once per day til the calcium is up to 400)
I asked about Kalkwasser as a means to bring up the calcium.
In their opinion, they thought the CaCl2 would do a better job for my purpose. They did recommend using Kalkwasser though, in a very dilute solution which you let stand and precipitate first; this water then used as topoff water. They said this would help CO2 buildup. Can anyone explain this - how that would work?
Also, I read in one of my books that if you use CaCl2, you want to use it in conjunction with a buffer. I am assuming that this is to keep the dKh at a good level. Is my assumption correct - can anyone clarify or explain in detail?
 
This site was very helpful about clarifying what happens between pH, dKh, and Ca. Also helpful to know that if you can't increase your calcium levels w/o lowering your alkalinity, its probably better to keep the alkalinity high! Right now my alkalinity is just where it should be, as is my ph. I will continue to watch all three parameters as I try to tweak my Calcium upwards....

Good info on the Kalkwasser too; I did not see any mention of the use of Calcium chloride. Anybody have any info on this?
 
Cathy, calcium chloride is what you typically get when you buy a calcium supplement to manually dose. When it hits the water, the chloride breaks away as it has a stronger affinity for sodium ions in the water, leaving Ca++ ions in the water for uptake by corals. Just substitute calcium chloride in when I talked about Ca++ on my webpage.
 
Boogie, that's a good site. Very simple and easy to understand (if only I knew math). I was wondering if I could print out a few copies and distribute them at the Petco I work at. We're getting saltwater next month and I think we're in a good position to provide some of the better aquatic service in the area (I know, big claim for a chain LFS:) ) but it's good stuff and it could only help my co-workers learn. Just asking for permission.
 
thanks, all, for the replies. Here's some chemistry in action. See what you think. since last Saturday, I have been adding carefully adding measured doses of Ca Cl2 to my tank. Checking calcium daily. It slowly rose to 380 from 360. In the same time period, my pH went from 8.2 to 8.3, and my dKh went from 10 drops to 9 drops. (if you want I'll get the package insert out and convert that to actual values; the desired target is 10 drops). Any comments on these observations? I didn't add anything today, decided just to recheck tomorrow.
PS all residents happy and healthy in the meantime.
 
If I'm understanding the dkh drop procedure correctly, this would indicate that your alkalinity is lower, correct? This likely the result of dosing the calcium, which is combining with carbonate (the buffer) and lowering overall alk readings.

This is just my experience, but you're not going to get calcium much above 370-390 ppm with manual dosing - you're losing too much as calcium carbonate, and you can't dose enough to justify the cost. Understand that these aren't bad calcium levels by any means; in fact, unless you've got a tank full of tridachnid clams or stony corals, this is plenty. But, if you want to get calcium much higher, I would start saving for the reactor rather than dumping money into supplements with no payoff.
 
thanks for the advice. I think I am just going to aim to maintain my parameters about where they are! If it ain't broken......
 
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