I wasn't aware of there being lithium in the Coralife. I'm not even exactly sure what lithium is, I will have to look into that. I don't think it is harmful to coral because I know the March 2009 totm on RC uses Coralife and that is probably the best looking tank I have ever seen. But is it harmful to humans? Doesn't Randy Holmes use Instant Ocean?
Yes, Randy uses Instant Ocean and always has. He says this about IO.
"IMO, those advantages to IO include cost, no organics such as vitamins, and no metal chelators."
and
"Here's my rational for using Instant Ocean:
I do not think there is a "best" salt mix. Nearly all of them will work fine as long as you know their pros and cons.
I don't want excessive borate, which leaves out Seachem.
I don't want vitamins or anything else organic in my mix (because I doubt their utility, they degrade with time to who knows what, bacteria may thrive on them as I store new salt water for a substantial period, they are totally undescribed with respect to amounts or identity, they are not naturally present in natural seawater at appreciable levels, and because I've occasionally had them mess with my skimmer),
so that tosses out some like Reef Crystals, hW Marinemix Plus BioElements, Kent, Coralife, and Nutri-SeaWater.
I don't want excessive calcium (long term use of limewater as I use drives up calcium, so I do not want it starting high),
so that tosses out a bunch, such as Kent, Seachem, Coralife and Oceanic.
There are certain companies that I will not support due to their misleading claims and/or product lines. That tosses out a few which I won't detail here since it is my personal thought as opposed to a specific issue with their salt mix.
I won't use certain lines of natural seawater due to excessive metals in it.
That only leaves a few to choose from, such as Instant Ocean and Tropic Marin Pro. The remaining ones might all be fine for me, but IO is lower in cost, especially if you get it when it goes on sale (which it frequently does). It also has a very long track record of success in many aquaria with relatively few concerning issues of bad batches."
A General Guide to Salt Mixes - Page 37 - Reef Central Online Community
Randy's comment on Coralife salt.....
"It used to be a poor choice, with greatly excessive lithium. It may be better now in that respect, but it points out that there is a lot more to salt than the big 3. I personally do not prefer the high calcium it has. I also do not like that it has vitamins added to it. "