Actually both statements in your hashtag are wrong, I have hatched and kept both triops and brine shrimp (For more than a week, and if you can't keep those why are you into reef keeping?) in 1/4 gallon and less for the brine shrimp. I have kept both species happy and healthy for extended periods of time.
Why am I into reefkeeping? I guess the same can be said why anybody is as this is pretty common sense, brine shrimp actually have relatively short life spans (one year is not an adverage life span.. 3 months is the longest and that's believed to be just a new generation of breeding brines rather than an individgual maximum life cycle). They're bullet proof in hardiness and can take any swings which is an excellant perk. (They can live in space believe it or not!) They're also saltwater unlike many suggest, but they do not live very long in captivity..
Unless you have a complicated breeding station to keep an endless supply, it's actually recommended to REFRIGDERATE live brine to get them to last long enough for feeding (the cold stunts their growth, lengthing their live span)
Tadpole shrimp/shield shrimp as their more appropriatly refered to (triops) can reach up to 4 inches in length, that's double the size of a 2" cleaner shrimp.. WHO NEEDS A 20 LONG! Ignoring the fact one is freshwater, that's just space alone. Tadpole shrimp are pretty acrobatic as all those "toy" aquariums suggest and do move alot.. needing the room.. I wouldn't put a full grown tadpole shrimp in anything smaller than a 10 personally. Especially with how messy they are.
I don't know exactly what systems you're running but honestly this is what I'm aware of and the experience of several other researchers rather than personal opinion or open minded thought of my own.
I do know some kits for brine shrimp that claim to be full freshwater.. I don't believe those are true brine shrimp, I'm not too sure I personally don't get involved with that kind of stuff (I had tadpole shrimp when I was really young I remember..)
Brine shrimp can only live a few hours in freshwater I know for a fact using them as feeders.