assjay suggested I ask you if 150ppm is too soft for endlers. I am thinking about what fish to put in a 10gal, and I think I would like to have endlers and some kind of dwarf shrimp. The thread for this is: https://www.fishforums.net/threads/stocking-a-10-gallon-tank.472588/
Real endlers can be kept at that rate. But a bit higher would be preferable if you have endler hybrids (so, with influence of guppy blood). But fry that are born in these conditions like yours would grow up fine with 150 ppm.