no offense here, but if you have 339 posts, u should be able to do a water change.
Take out the nasty water, collect any floating scum at the top in the container. Dump the nastiness in the toilet or sink. Next
mix the amount of salt needed with R/O or distilled water. Let it sit for at least a half a day, a day to play it safe. Once the salt is dissolved, pour it in, and top off the water with more R/O or distilled water. Nothin to it, really. Good luck.