CaCl from Pool supply for Calcium Supplementation

[Mountaineer]

For the last 2 and 1/2 years I have been supplementing my tank using a 2 part system with Arm and Hammer baking soda and Calcium Chloride Flake I get from a pool supply company. I know this will shock and terrify some of you to use anything that would come from a pool supply company in your reef tank while others will not blink. I assure you that I have had no problems and I stumbled onto this gem when adding Calcium to my pool a couple of years ago and realized that it looked just like Dow Flake. So, I looked for the MSDS to see what this actually was that was being added to my pool and I have been using it in my reef tank ever since. I will link the MSDS below.

 

CaCL MSDS

[Origami]

Calcium Chloride from a pool supply house is an accepted means of getting the stuff. I'm unfamiliar with the brand you've listed. Tetra is often one brand that is looked for. Tell me, where did you find the stuff? Also, if you were to dissolve a 1/4 cup of it in a quart of water and let it sit for 12-18 hours, is it still clear or do you see a residue? Just curious. Some Tetra from Finland recently displayed a residue which was unfortunate. The stuff from China seemed to dissolve more cleanly.

 

The MSDS doesn't, unfortunately, tell you much about the trace impurities of the product, though.

[Mountaineer]

This brand was not purchased locally and was purchased before we moved here and I brought it with me. Your right, the MSDS does not tell you about trace impurities, but neither does most any bottle found in a pet store. As for solubility I have not noticed a residue and it claims to be 100% soluble. I think I paid about $10 for the bucket.

[Origami]

This brand was not purchased locally and was purchased before we moved here and I brought it with me. Your right, the MSDS does not tell you about trace impurities, but neither does most any bottle found in a pet store. As for solubility I have not noticed a residue and it claims to be 100% soluble. I think I paid about $10 for the bucket.

 

Yes, but the reefing community is cautious about impurities. And, depending upon the processing method and the factory, the types of impurities may be of concern. To the best of my knowledge, the only trace impurity study for the hobby was performed some time back by Randy Holmes-Farley, a chemist at Genzyme and one of the most significant contributors in the world to this area of our hobby. That study is the basis for hobbyist use of old DowFlake. I say "old" because, in the last few years, Dow changed the process by which they manufactured their Dowflake. The new process results in higher levels of bromide impurities in the product (which is manufactured as a road de-icer with a secondary use as a pool additive). An analysis, performed by another chemistry-type over at reefcentral summarized that these elevated bromide levels could be managed with regular water changes. Other sources of Calcium Chloride (other than Dowflake) that routinely see hobbyist use always carry some sort of caveat because it's not been analyzed. This includes Tetra, CForce, and other brands. However, other sources are definitely used. Even within a particular manufacturer, product can differ from manufacturing site to manufacturing site. Randy does say (in the article linked below) that you're probably safe using USP, food, or FCC grade calcium chloride. I suspect that, most often, this (food grade) is what you find in those bottles and jars that you mention.

 

http://reefkeeping.com/issues/2006-02/rhf/index.php#16

 

I'm glad that you're not seeing a residue. Some stuff out there definitely has a residue that appears several hours after it's mixed into solution. It's unclear to me what exactly the precipitate is. At first, I thought it was an oxide of iron, but tests for iron turned up negative. That's neither good nor bad - just undetermined. Of course, not having a residue doesn't indicate a lack of impurities. It just makes one feel a little bit better, I guess.