Strontium, molybdem, magnesium and a whole bunch of other trace elements found in seawater according to KENT.
I know what they list, but they do not list everything in it, nor say how much, nor say anything about the counter ions. That is why I cannot say whether it is mixable with the calcium part or not.
If such trace elements are being depleted then water changes aren't going to keep up (unless you are changing A LOT of water very often). I am quite lazy with water changes and thought I was covering all bases by using these products.
How do you know that? Aside from reading sales literature from companies that sell such products? Real studies have show plenty of many of them (perhaps not all) in aquaria that do not supplement them. I've not added anything except foods, water changes, iron, and silica for many years.
Check these resources:
Ron Shimek's Tank Water Analysis Article
http://reefkeeping.com/issues/2002-02/rs/feature/index.htm
Reef Aquarium Water Parameters
http://www.reefkeeping.com/issues/2004-05/rhf/index.htm
Reef Aquaria with Low Soluble Metals
http://reefkeeping.com/issues/2003-04/rhf/feature/index.htm
FWIW, I do not doubt that one or more things in such a cocktail are desirable. But I think it equally likely that one or more is already too high, and adding more may be detrimental. On balance there is little data showing the benefit of adding such trace element cocktails, and since every brand is different and most ingredients are secrets, aquarists do not even know what they are getting or whether results with one have any relationship to results with another.
Randy, assuming zero water changes, wouldn't there be many trace elements normally present in NSW depleted from not being supplied through any of your 3 DIY additives?
There are many 'impurities' in all of the ingredients that essentially are "trace elements". Potassium, for example, while not a trace element (but rather a major element) is present at quite high concentrations in the Dowflake, just about right to keep it balanced.