Jon, this is kind of aimed at you because I know you were talking about this at the end of last winter.  Have you done any more research on this now that these products are comming back into the stores?  I was in Sam's Club yesterday and they had 50lb buckets of what said pure calcium chloride for $15.  Futher looking at the ingredients showed the following:

Cas no Calcium Chloride 010043-52-4

Cas no Sodium Chloride 007647-14-5

Cas no Potassium Chloride 007447-40-7

Cas no Water 007732-18-5

Do the numbers at the end mean anything?  I noticed the exact same numbers on a different brand.  Is this the right kind of calcium needed for our tanks?  Is the potassium a bad thing?

I've been using Dow Peladow brand ice melt.  It is "pure" anhydrous calcium chloride.  Dow Dowflake is "pure" hydrated calcium chloride.  Randy Holmes Farley analyzed Dowflake for impurities and compared it to other calcium chloride aquarium products in this article:  http://www.advancedaquarist.com/issues/mar2004/chem.htm - http://www.advancedaquarist.com/issues/mar2004/chem.htm

The Peladow that I've been using, according to Dow, is just Dowflake with the mosture removed.  I've not noticed any ill effects from this (and I've been using quite a bit).  So... the only snowmelt that I would feel comfortable using is either Dowflake or Peladow.  Although, I wouldn't be a bit surprised to find that many others are just as good.

If you want to try out a different brand, look for a product that is pure white and is mostly calcium chloride.  Pure anhydrous CaCl2 should be about 97% CaCl2.  Peladow is 90% and about 3.7% (other salts... mostly NaCl) so there is still a little mosture in the product.  Fully hydrated CaCl2 would be 70-75% CaCl2.  Prestone markets a snow melt that appears to fit this description.  I probably wouldn't use any product that was less then 70%. 

Re: the CAS numbers
CAS (Chemical Abstract Service) numbers are a unique number given to every chemical known to man.  The name calcium chloride might mean something different in France, but CaCl2 will always have the same identifying number.  To you and me that number means nothing

You would use either the Dow Peladow or the Dow Dowflake.

Yes

Which would you prefer and where can I get it?

Either and I'm not really sure where it's sold .  I got my 50 lb bag of Peladow off a big pallet at my work.  I'll ask our purchasing agent where she gets it.  Before I noticed the Peladow here at work, I bought a container of Prestone Driveway Heat (I saw it at Home Depot and Checker Auto last winter).  I think that this material is packaged by Scottwood Industries for Prestone and is the same as Scottwood's Excel product:  http://www.scotwoodindustries.com/Excel%20-%20MSDS.doc - http://www.scotwoodindustries.com/Excel%20-%20MSDS.doc   If I couldn't find either of the DOW products I would probably try the Prestone stuff.  As a matter of fact if you want to try this stuff out you can have my package of Driveway Heat.

I just noticed that in one post I said I would only use one of the Dow products and in the next post I said I would probably use the Prestone product.  I must be confused .  If I were to use the Prestone stuff I would go very slow and watch how everything reacts to it, before going hog wild. 

I talked to Univar who is the distributor for Dow in Utah.  They sell to a number of places (but not to indivuduals... unless you're buying a pallet load) and suggested I try The Janitor's Closet (532-3812) or Waxie Sanitary Supply (367-5490).  Both places are selling 50 lb bags of Peladow for $18 too.  It looks like it won't be that hard to find afterall.

Good news on the Prestone stuff too...

So you are using this as an unbalanced calcium additive? What do you use to keep your alk up?  What would be the advantage of this over something like Kalkwaser? Both are pretty cheap. Can this be added faster than kalkwaser?

Jared,  unbalanced additive.  I use baking soda (or baked baking soda, washing soda) for alkalinity.  The advantage over kalkwasser is that I can add whatever the tank needs without really effecting pH.  The disadvantage is that is unbalanced and prolonged usage can lead to higher then NSW levels of sodium and chloride.

Kevin,  I'll check when I get home, but I'm pretty sure it had a Scottwood Industries logo somewhere on the label.

Sure 'nuff.  My Prestone Driveway Heat says "Distributed by Scotwood Industries, Inc".

I wonder if the Prestone product uses both the Dow and The Scottwood when they repackage depending on pricing/availability. Was there labling on your container showing Scottwood?

It could just as easily be the other way around... i.e. Scotwood doesn't actually "manufacture" anything they just buy in bulk, repackage and sell under their name.  Happens all the time.  Excel = Driveway Heat = Peladow.  And I think Dow is one of the largest calcium chloride producers in the USA.

Kevin's got it.

It doesn't really matter if sodium bicarb or sodium carbonate is used for alkalinity additives.  They both will equalibriate with atmospheric CO2 within hrs/days once added to your tank.  I use sodium carbonate because the intial mixture has a high pH and my tank suffers a bit from chronic low pH.  Many people actually mix the two together to get a mix that mixes up with RO water to pH of about 8.2.

Kevin's right again.  I've used A&H Washing Soda too.

If you're using Peladow and washing soda it is 1.05 grams of Peladow for each gram of washing soda... 1 to 1 is close enough for me.

I'm still using kalkwasser.  I just use the peladow and washing soda (baking soda) to nudge everything back up 'cause the kalk isn't keeping up.

Yes a reactor is being drawn up in my head as I type, but...

I just made up some DIY B-ionic that I'm trying out.  I'll post about it after I've used it for a few weeks

Theres no way to know what the impurities are in a bulk industrial soda ash product.  But you can be fairly sure that a food grade product is not going to have many toxins (i.e. if it's good enough for my belly, it's good enough for my corals).  So I use baking soda.  I spread it out on a cookie sheet and bake at 300F for about an hr.

Oh ya... I've also used Arm and Hammer Washing Soda without problems too.  It's not a food grade product, but in my experience it's ok.  But it's not as easy to find as baking soda.

I test my calcium and then use the reef calculator to see how much to add.  the hard part was determining exactly how much water was in my tank.  I am still in the process of testing to see how much I use every day.  Every tank will use different amounts depending on what's in the tank, and how much Ca is used.

Fax

Test results are in.  I use about 10 ppm Ca and about 1dKH/day.  I also added an enteral feeding bag to slowly drip the baking soda in the tank.  It ands up being about a teaspoon or less so I just dissolve the baking soda in a cup or so of water and pour it into the bag.  It has a drip adjuster that is set at about 2 drops/sec.  It probably takes an hour or so to drip 8-10 oz of the mixture, no pH swings.  I am probably going to place and order from the supply house soon so if anyone wants one I will create another thread.

Fax 

The calculator is great.  Prestone driveway heat is Anhydrous CaCl2.  The Seachem product is also listed on the calculator.

Fax

I use Peladow and have not had any problems, but any Dow product after 2007 contains an elevated level of Bromide, many have used the new peladow, prestone driveway heat, without a problem but it is still basically uknown if elevated levels of bromide can cause problems and at what level you would start to have issues with it.