I am fairly sure I will never start up a new tank. If my tank ever crashed now, I would probably leave the hobby as I have been in it since the 50s and I think that is long enough. My wife and I would do some more traveling and maybe buy another house in the tropics someplace. Maybe open up a resort for retired Supermodels.
But if I ever "had" to set up a tank from scratch maybe because we are being attacked by Vampire Neanderthals from Bayone New Jersey and the only way they would leave you alone is if you set up a new tank, then this is what "I" would do.
If I only had ASW, which is fake seawater I would get that, hopefully on sale and I wouldn't care what brand it was as I don't think it matters. I would also use gravel like crushed coral or like I use now dolomite, but I think that stuff is extinct. ;Wideyed
I personally would also put in a reverse undergravel filter. When you stop laughing I will continue and if your tank is older than mine and you don't use a reverse UG filter, write your own thread and I will go and buy that house in the tropics and read your thread as I am drinking a rum punch while being massaged by an out of work coconut picker.
Put in some rocks, as many as you can afford. If you are near the sea, collect some of those. If you can get live rock, it is better.
I would add a dead shrimp, clam, emu, road kill or any other dead thing. If it's a 100 gallon tank I would add 2 dead shrimp or maybe 3. It doesn't matter as we won't be eating that shrimp. The bacteria will.
I personally would also add a hand full of garden soil with no fertilizer, bug killers, week killers, roach killers, mole killers oil stain remover, STP etc.
If I lived near the sea, I would add about a cup full or two of mud from there. (I would also collect NSW but I am assuming you can't or don't want to.
If you can get NSW but you are afraid of parasites, pesticides, hypodermic needles, pollution etc. You are in the wrong hobby or in NaNa land and should never follow anything I write.
The water should get cloudy and maybe even stink. That is fine. Sometimes bacteria stinks. The bacteria will eat the shrimp. They will start to like you, not so much the shrimp.
You can test the water if you have nothing to do but it is not necessary because you are "not" putting in fish now.
After the water clears, throw in another couple of shrimp. The water will clear again. You can keep adding shrimp as the water clears.
Buy a fish, not an Achilles tang, pinecone fish, purple tang or anything expensive, but the cheapest fish you can find. Maybe a clown.
This is opposite what I do in my tank now but this is for a brand new tank with new water, new rock, new bacteria and maybe a new girlfriend.
Take that fish and put it in a separate tank using water from the tank that just cleared with the dead shrimps. Add some copper like it says on the bottle. If you can get it also add some quinicrine hydrocloride (10mg/gal) but if you can't get that or something similar, don't worry about it.
Throw some thing in there for the fish to hide but "not PVC elbows" as fish hate anything new and white. I would break up some new red bricks from Home Depot. If you have old bricks you can use them but not with tar, shoe polish, anthrax etc. on them.
You will need to change some of that water every day along with copper and add water from your main tank. Replace that water with new water.
Stick the fish in there for ten days. No more. Feed it small pieces of clam or better live blackworms. If you can't get that use LRS food.
After ten days put that fish into the main tank. He may get some spots. Leave him there. People on forums will tell you to catch him and treat him for 72 days and leave the tank fallow.
Forget those people and go and watch TV, not Oprah or Dr. Oz. Go for National Geographic.
Any spots should clear up. If not, he will die and you will have try again, but I think he will be fine. That fish is now immune and you can put him in the same tank with a sick leatherback turtle or manatee, but don't.
Change some water as the nitrates are through the roof.
Then get another fish, not a clownfish because the first one will think who he is and may kill the first one. Maybe get a bleeny or gobi.
Do the same thing.
After some time, maybe 4 months don't do that quarantine 10 day thing. Just put new fish in.
The theory is that no new tanks with new water are healthy no matter what you do. Most of those tanks will have problems no matter what you do. Moses, Noah, Jacques Cousteau and a marine biologist with more degrees than a thermometer could help you set up a tank from scratch and you will most likely have problems.
Don't worry about it unless you stupidly started the tank with a $200.00 clown triggerfish which I said not to do.
The ten day "quarantine" period is because that new clown will have parasites as "ALL" fish from the sea have. You don't see them i the store because the fish is in copper or some other parasite medication. The store owner won't tell you that but that fish is not in chicken soup, it is in medication.
When you remove him from medication he will show spots. It is normal and not important as we actually want the fish to have some parasites. The fish will never become immune unless he is infected just like if you never get measles, you are not immune from it.
Unfortunately you need the fish to be in contact with diseases. Sorry people who quarantine this is "my" method. You can write your own method as many people do.
This entire method counts on the fact that a week ago that fish was in the sea, maybe swimming around the feet of Angelina Jolie and her 15 kids. He was eating fresh food at every meal and that food all
"HAD PARASITES" in it. Fish were meant to eat that as I have never seen one in Burger King unless it was on a plate with special sauce or whatever they put on fish as I don't eat there.
That clownfish was immune in the sea as he was swimming and eating parasites his entire life. That ten day copper treatment isn't long enough to remove the fishes immunity but 72 days may. Eventually we have to introduce fish from the sea "with" the parasites and diseases because we actually "want" to have a breeding population of parasites to happily live along with the fish. Remember, no parasites = fish with no immunity.
Now that those fish are immune, buy whatever fish you want. It doesn't matter as long as you followed this and didn't quarantine or medicate too long. That ten days won't kill all parasites. And we don't want it to, we just want that weakened fish from the store to build up some strength to fight them off while he is getting his immunity working.
Now keep feeding those fish something with live bacteria in it like worms or clams.