At the start of this year, I was motivated to start growing Sea-monkeys again by a fun, informative website: www.KingoftheSeaPeople.com
It's an interesting site with a blog written by 'His Royal Highness' Jon, the site owner. Have a look at the site and if you'd like some more light-hearted but very informative reading, I'd highly recommend his e-book (Kindle version), "Raising Sea-Monkeys: A Beginner's Guide to Being a Great and Powerful God!"
I set up a heavy-bottomed glass as a tank. The heavy bottom reduced the risk of it being knocked over, and the thin glass sides gave clearer visibility than a jar or a plastic tank. The mesh cover was a plastic lid with the centre cut out, with a circle of net material over the top, to stop dust and bugs from contaminating the water.
I had the glass on my desk with a lamp overhead for light as my little room has no windows. I took the sea-monkeys home at weekends (tipping them into a clean jar with a lid, then taking the lid off at home and replacing with a mesh cover).
When I decided to split my sea-monkeys into 2 tanks, I needed more "salt water". I guess I could have used packs of Plasma, but that's a bit hard to get in Australia, and would work out expensive. I read up on brine shrimp and realised I could use solar salt. Here's how I made my salt water.
I went to a local aquarium supplies shop and bought a small bag of Solar Salt (they just ladled out a scoop from the large pack they use for their salt water fish tanks). I also got some bottled water.
Then I got a glass jar with a plastic lid (so it wouldn't corrode), a teaspoon (5ml size), and a measuring jug. I washed these thoroughly with boiling water and rinsed with bottled water, just to be sure.
I measured 200ml of bottled water in the jar, added a level teaspoon (5ml) of solar salt to the jar and stirred thoroughly. Then I let it sit for a day to dissolve completely, stirring a couple more times. I read up some more and decided to make a weaker salt solution, so I added more bottled water to fill the jar.
I used this solution to top up both my tanks and also to make a "hospital tank"- a small, thoroughly-cleaned jar with a small amount of salt water and about 1/2 small scoop of Sea Medic. I "isolated" some sea-monkeys who looked listless into this jar (using my medicine dropper to suck them out of the main tank).
In a day or 2, several had died (so I disposed of the bodies), but one small one was swimming much more vigorously so I restored it to the main tank. It is still growing and looking happy, weeks later.