I think you will find that most people prefer IO to any other salt on the market. IO and Reef Crystals are made by the same company. I have been using Reef Crystals since starting my Reef a little over 1.5 years ago. Everything I've read on the Internet says that most reefers use IO and are happy with it. The next bucket I buy will be IO.
Acording to the label, RC is supposed to have more trace minerals. If you dose Calcium, then there is no need for RC.
What are you using now?
I've been very happy with Reef Crystals. Although I can't image that there is much difference between the IO and Reef Crystals since they are both from Aquarium Systems.
i used IO right now but bought RC to help w/ my low ca problem. i have a 10gal nano and use ro/di (0ppm) water and IO only gives me ca+ of 350. i need more ca because it is a small tank and i can't really dose w/ kalk. so i use IO w/ liquid ca. i will make up some RC and test for ca+ and see how they compare.
i got RC because it is made by the same company as IO and i think their salt is great
later
Lunchbucket
if you search there are lots of other polls on salt on this board...maybe get some more oppinions there.
Kent is better then Reef Crystals. I switched over to RC thinking that it had high calcium content. But a month or 2 after starting to use it i decided to test my calcium. It was somewhere south of 300. I tested some new RC water that i had in a jug, it too was south of 300. I used Kent prior and it was around 370. I dumped all of my RC, and bought another bag of Kent. that tested around 400 for calcium. Also my corals are looking good now with Kent, whereas they werent looking so hot in the RC water, which is why i decided to test to see what was going on. Maybe i just got a bad bag of RC, but im sticking with Kent.
Over the years i have used IO,RC ,Kent been using tropic marine for 6 yrs and as long as it is available to me Ill keep using it dissolves clean no residue on container.
I have been using coralife salt since I started my tanks. The LFS here has it for 10 bucks a bag. That is a lot cheaper than anything else I have seen. I haven't had any problems with it (that I know of). Anyone else use this stuff?
In the past 13 years I've used instant ocean, reef crystals, marinemix, DAS red sea salt, coralife, and Kent.. IO was the first one I used and it's again the one I use now.. I have never experienced any difference what-so-ever in terms of tank health.
fwiw: I was very happy with the DAS evaporated red sea salt as it seemed to dissolve very quickly. Eventually it became scarce and I ceased using it.
Over the years, I've used every type of salt that's been on the market. Only noticable difference between them all is some disolve slower than others. Never saw one outperform the other (in the tanks). Some say Tropic Marine is better, but in lab comparisons it doesn't rank at the top. Personally, I think the differences between them all are so minor that it's not an issue, that's why I go with the cheapest aval. For me, I use Coralife that I get for $28 for 150G bucket and it comes with a free Coralife T-shirt. Can't really beat that. IO is pretty cheap too. If they only gave a t-shirt....