I've been building up my equipment for this 90 gallon reef tank I'm currently putting together, and the one thing i am not clear on is the refractometer. I say that because they all look the same, while some are substantially more expensive than others. Are there major differences in quality and reliability between the brands? Also, how do you create an actual build thread that has the link in your signature? I'd like to do that even though the tank is still very much under construction. Thanks!