Letting your water sit will get rid of chlorine but that’s about it, better to spend the extra money (there’s enough for about 500 gallons in the bottle I buy) and get your water conditioned. And as far as the worms, I would either get an organic insecticide like neem oil or get some new medium to grow in entirely. Remember the more you put into it the more you’ll get in return, as of right now they have all the nutes they could possibly need but i would invest in some fox farm soil for once they get a little bigger.