I ran ESV for 5 years then switched back to IO regular when I could not get it due to covid.
I see no difference in my systems except IO is a much lower cost.
I use sodium bisulfate to lower alk.
do you have corals? but you can take mostly any brands, any type of salt. Most of the rest is marketing strategy. only reason I had to change salt in my years of reefing was price, availability and brown residue left by some brands in the mixing tank.
What is this brown crud people are talking about with Reef Crystals? I haven’t seen any of this.
From my experience, if you store saltwater made with reef crystals long enough (especially heated), it leaves a brown residue on the container which can also get into your tank unless you filter it out with a sediment filter. While no one has reported any specific issues with this stuff getting in the tank, it's definitely annoying to have to clean it out of your storage bin constantly. I'm considering switching myself just to not have to deal with it anymore.
When you mix up Reef Crystals and let it sit in a mixing station, I'm not sure if occurs if quickly used, there is a brown residue left in the mixing container. I've seen different explanations to what it is but most people seem to say it some kind of anti-caking agent that gets added to prevent clumping, but I honestly have no idea. All I can positively say is that it, as confirmed by Randy Holmes Farley, it doesn't cause any harm to the tank.
Mine does it with unheated water, and I've considered switching to regular I/O because of it. It will occasionally plug my AWC line causing me to have to clean the end of the line. I rarely clean the mixing container because of it though.
