To AC's points:
1) UT yields bad Mg. Good to know. I'm not aware of any good DIY sources of Mag. Chloride. Anyone?
2) Thank you, but I confirmed to my own satisfaction that any Tetra product is generally unavailable - should be easy for most to avoid.
3) Regarding cost, your examples fail to address the very relevant difference of fixed and ongoing costs. I think most hobbyists, whether they think in those terms literally or not, have a firm grasp on the difference. Further, many people are heavily into DIY lighting to save money - particularly DIY LED's - just for another example. The hobby used to be astronomically expensive in all aspects - in many regards it still is. Thanks in large part to the spread of knowledge on forums like this, DIY lighting and chemistry - to say nothing of all the other DIY (stands, sumps, skimmers, etc) that have been built in the name of DIY and saving money - the hobby is a bit more affordable for those that have more time/ingenuity than money. This is good because in net it means more people in the hobby (than otherwise) despite the persistently bad economy.
4) I'm not sure it's been proven anywhere outside of Red Sea Fish Pharm that NSW-based ingredients are better in any way, has it? They have a lot invested in desalination infrastructure in their home country, so it makes a lot of sense from their perspective that they'd use and promote that resource - by-products of desalination - preferentially. Any "by products" business offsets some small amount of the enormous costs of operating one or more expensive desalination rigs. I'd be surprised if it wasn't a state-financed/sponsored institution there, in fact.
Personally, I am testing/corroborating others' experience in my own use of this DIY calcium product and figure that's enough for my own part. Nothing really new but my research for affordable CaCl2.
Generally, if people are honest with themselves - and this may be more to AC's point, and perhaps surprising to any super-cheap-o's in the crowd - commercial salts (Ca, etc) are
often worth their additional cost, especially if one's tank is still low on the consumption curve. E.g. $10-$40 every few weeks or months for a couple of bottles of
Brightwell or ESV (to name just some more commonly available ones) isn't very significant. Often less than $1/day...even a lot less. However, when you're going through
four bottles a week or even more, then there's room for considering other options IMO. My experience is that no commercial suppliers to the hobby cut bulk discounts...perhaps if things were different.
I don't think it's news to most here, but just to make sure it's said: DIY chemistry is not for everyone. IMO, at least. Hopefully one doesn't have to get far into the prospect of DIY chemistry to realize that...
...some DIY chemicals are fairly dangerous and messy to handle,
...you get no helpful instructions (i.e. ..apply product to driveway...),
...the product's density and exact hydration level is hardly ever known, so one has to get experimental and a bit creative to tell what concentration is actually being mixed up (crucial if you want to use any of those nice dosing calculators on the internet) and
...yes, there is a little bit of mystery as to what the precipitate is, but that hasn't stopped a lot of people's success,
...and as I already said, one is not really going to save any significant money unless really dosing a lot of material.
It's worth pointing out that there are also commercial products in the hobby one can find fairly easily on the internet or on the LFS's shelves, usually priced at a premium level as the brand might suggest, but which are horribly labeled and practically impossible to use properly - regardless of ingredients or user experience level. "Buyer beware" is most definitely in effect even for hobby-targeted commercial brands, not just DIY products.
One last time....for all these reasons, and some of the ones stated in other postings - DIY chemistry is not for everyone.
I hope this helps!
-Matt
