Poll-What type of salt mix do you use?

There is a pretty big difference in the various types and mixes. The reason salt maybe good to one individual and not another has to do with mainly what the individual is growing in his or her tank.

For example Instant Ocean produces 2 types of salts. Their standard Instant Ocean salt mix and the Reef Crystals salt mix. The biggest difference between them or any other salt is the Mg/Alk/Ca concentrations. In summary you usually can tell how much Mg/Alk/Ca is in a salt mix by looking at its DKH most of the time. Remember DKH is also pretty important in salt water tanks. Some mixes will actually have a ton of MG and way less alk/ca, yielding you a low dkh but these types of salts are for people who want to dose their own specific levels of alk/ca.

Didn't want to go too in depth but yes their is a big difference and depending on what you do or grow in the hobby, the right type of salt is actually required.