I use Red Sea coral pro. It does mix well, I dont Get much residue in the bottom of my mixing station. All my buckets have been consistent and has worked great for me. I keep a mixed reef tank.
I have used this salt since I started. Only one time I “borrowed” some reef salt from a friend when I was in a pinch. Instant ocean and it left a brown residue in my mixing station. I made 15 gallons and after there was a good amount of residue. But a lot of people use it with good results and can’t beat the price.
Esv- b ionic for 3+ years now.
Super easy to mix and can be used right away.
It mixes to about 9-9.5 alk.
I reduce it to 7.5 with sodium bisulfate while running a powerhead and air stone.
Ph drops from 8.3 to 8 which works for me as I can use it at that ph.
Reef crystals, IO, and lately more Live Aquaria. But as others have said, it's not about the salt, it's stability and other parameters like nutrients. For me the best is a large crop of chaeto. I run it in a 60 gallon refugium and my 200 gallon Rubbermaid sump and have a fairly heavy fish load. Salt doesn't matter when things are stable as long as you do smallish (10%) changes. I alternate between them, but haven't been doing much water changes the past few years and things have been good.
After a decade of using IO/RC, and fussing about having to clean the brown film from my mixing vats, I switched to Tropic Marin Pro Reef. I have a much larger mixing tank now, and dreaded the thought of having to lug it out of my basement, scrub it, and set it back up. The BRS investigates sold me on TM/PR. I can now mix up enough saltwater for three water changes, and not have to worry about parameter swings in storage, but most of all... it mixes CLEAN with no residue. Yeah, I'll pay more for those bonus features.
TM pro for me. Watching the brs videos I thought my first salt should be what they call the "best." Got it in the mail yesterday mixed fast with a cheap green 800gph pump from Amazon, no heater as my rodi water was at 78 already. First time mixing salt, seems easy, but took more than recommended to reach 1.025
I've used Instant Ocean, in the past and Instant Ocean Reef Crystals for the last few years. Reef Crystals dissolves better and doesn't seem to have much, if any, junk separate out (maybe I'm just lucky?). It's the better budget salt that I've used.
That being said we always let things settle before pouring in the fresh salt water. Then we dump the last little bit just to make sure any crud doesn't go in. Lastly as others have said watch for chemistry changes when you switch buckets (and I would say that this is true for all salt mixes but probably especially Instant Ocean salt).
Keeping all this in mind, and the small amount that gets wasted, I think Instant Ocean Reef Crystals is really good bang for the buck.
Brightwells as well. Although seriously thinking of switching to tropic marine. Getting tired of cleaning brown gunk out of my mixing station a couple times per year.
There's basically no difference in price between red sea and tropic marin because a 5 gallon bucket of tropic marine makes slightly more gallons of saltwater.
Personally I can get Red Sea at my LFS so I use a mixture of Red Sea Blue and Red Sea Pro. This helps keep my ALK lower. I've been using it about a year and I highly recommend this mixture.
Occasionally it will leave brown residue on my plastic trash cans.