Oh sorry I meant it was a tablespoon and a bit of salt and then a few pinches (okay I am usually pretty liberal here) of baking soda to buffer the pH.
Usually if I am being exact I do 1.5L of water to 1.5 tablespoons of salt. Don't know if this is under/over kill on the water to salt ratio but it works and I'm sticking with it haha. I used to use less salt and it still gave me BBS. I just want my BBS to hatch as soon as possible so I figure that more salt should hopefully increase the rate a bit.
When you make a new batch I like to pour out and give the hatchery container a good rinse out. I read somewhere that not rinsing it properly can lead to a less successful hatch rate and so I just do it as a precautioun now.
Hope that helps. If you get a smallish spawn, it takes only a very tiny amount of BBS eggs to feed them all. I have lots of small spawns in my grow-outs (from 5-50 individuals) and I am always hatching too much BBS and subsequently having to chuck it out.