I have a Calcium Chloride question. There was some question as to the purity of Dowflake awhile back... some element that I don't recall potentially building to harmful levels in our tanks. Has this been settled?
I ask because I'ill probably run out of the anhydrous CaCl that I currently use and found a local source for Dowflake. I don't know it's batch number but the front of the package states "77-80% pure". Will this be safe to use?
Several years ago, DOW made a change in the way it produces DOWFLAKE and PELADOW (essentially any of its Calcium chloride products). DOW used to remove the bromide from its product, but then stopped doing so. This initially caused much concern in the reefing community that bromide would be detrimental to a reef tank.
A second manufacturer that uses a different process to make calcium chloride that does not have the bromide is Tetra Chemical Corporation.
While bromide is now in the new DOW formulation, you should keep in mind that bromide is present in natural sea water (NSW). The actual DOWFLAKE concentration of bromide (7,000 ppm) compared to calcium (280,000 ppm) is very low when you consider how much you actually dose per day. If you do any water changes, have actively growing macro algae, skim, or run carbon, then you are eliminating the bromide or its byproducts from your tank.
Based on what I have read and my own personal experience, there is no need to fear the use of the new formulated DOWFLAKE in your tank. If you want to use the purer form, buy the calcium chloride mix from various online vendors like Buckeye or from another chemical manufacturer like Tetra Chemical.
Personally, I use the DOW product called PELADOW with no adverse affects on my livestock that include fish, crustaceans, soft and hard corals, snails, and all the flora and fauna associated with the reef tank.
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