I find it hard to believe that "fake saltwater" is bad, seeing as how there are at least a few very nice reef aquariums running on fake saltwater.
I didn't say Bad. "bad" is a bad word. I said NSW is better. It's better because it is already aged millions of years. NSW has every mineral or element on Earth in it. Substances exuded by algae, metals, meteorites, volcanoes, bacteria, funguses, sponges, corals etc. ASW has chemicals, all dry that are mixed with water in the hope they become hydrated to the same composition as the real thing. It is not.
NSW is also loaded with bacteria and viruses, both good and bad in the exact proportions that they are supposed to be to keep each other in check.
My own reef ran the first 45 years with "mostly" asw and I had very few problems, but after it aged, I had no problems. Not even with diseases.
ASW is sterile. Sterile is not as good as "aged" which is why you would not have much luck putting corals in a tank with 100% new ASW. They would look horrible. But you could do that with NSW.
There are chemicals in NSW that we have no idea if they are used by organisms so they are not added to the mix. Most of them are trace elements that we can't or don't test for.
ASW becomes much better after it ages and if we keep changing to much of it, it will stress the fish but mostly the corals.
This is also the reason IMO that new tanks have so many problems with algae, cyano, ich, velvet etc.
My tank now, because I live next to the sea is all NSW. I have no algae, cyano, ich, velvet or any other problems and I would never quarantine as diseases are a non issue.
I have not had those problems for many years but I feel one reason for that is the age of my water.
Look at the disease forum, virtually all the problems and diseases are in new tanks. You rarely find any diseases or problems in tanks 10, 20, or 30 years old.
Most of us have to use ASW. I get it as I also had to use it. But when it is new, out of the box, it is a far cry from the real thing.
But I didn't say "bad"
