I drained a 150 gal rubbermaid 2 months back. It was loaded with ghostshrimp, crawdads, Gams, FHs, and 1 well fed RES. The salt content was up due to benefits, I had read online, to the shrimp, crawfish, and RES. I sorta tasted the water once, pretty salty (ack) yet my simple floating salt meter said it wasn't close to being enough for salt water fish. It was about triple the recommended level suggested for aquariums. For 18 mo. all the critters remained healthy; the shrimp 'an crawdads reproduced abundantly.
