Epsoms salts ok?

I second (or thrid or fouth that Epsoms are OK) Not the preferred method, but nobody really knows that SO4 is harmful or at what quantity that they are... I'm sure it does upset ionic balance somewhat, but as was already mentioned water changes will help. I would add however that I wouldn't use Epsom Salts for anykind of Mg treatment (elevated Mg levels) to eliminate nuisance algae, as you are at that point looking for trouble.