I have just been dumping unhatched eggs into the 10 g. I started by feeding it yeast dissolved in sugar water. Once my phyto culture got going i started feeding live phyto. I've heard spirulina powder also works well. I also throw in spare bits of food and i use my old tank water after WC to fill the brine tank.
one of the biggest factors I've noticed on brine density is specific gravity. I did some research on where my species comes from (it is the san fransico bay brand the latin name is like fransicana or something). It is grown in extremely high salt content water. It is actually grown in SF bay and the only other place is THE salt lake in UT. Obviously salt content is ridiculously high. I have noticed they seem to really prefer massive salt quantities.
Not sure its a solution but hopefully something i said is remotely useful lol. Lmk how it goes and Feel free to post pics!