I wanted to finally get an Apex to take control of may tank. I do not really need the ORP or salinity checkers that are on the regular apex system. But I do want to be able to get the trident later on to test my water and then also get the dosers for when I need them. Do I actually need to buy the more expensive regular Apex or can I use all of the other add on elements with the Apex EL version? Thanks