With the exception of calcium supplements when needed (when calcium levels go below 400), I don't add anything to my reef tanks. I keep corals, clams and anemones. All trace elements that are needed are found in the salt mix. And, the concentration in the salt mixes are MUCH higher than in natural sea water.... so supplementing them is not needed IMO.
BTW.... if you aren't testing for strontium & molybdenum.... why would you ever take the word of a LFS or a manufacturer and add it in your tank? Again, the levels of both in salt mixes are higher than those found in natural sea water.... so adding even more of both is IMO just a waste of money. Doing regular water changes will keep everything where it needs to be.
I'm sure you're not hurting anything (except your checkbook) by adding different supplements, but unless you are testing for everything you are adding I would seriously re-evaluate what you are doing and ask yourself WHY you are adding things. If it's just because "someone told you to", then perhaps you should ask others for their opinions.
There are quite a few "salt studies" on the internet comparing salt mixes to natural seawater. These studies compare different salt mixes and the elements contained in them to natural sea water. You'd be amazed at the high concentration of elements in most salt mixes compared to NSW.
Don't misunderstand though, sometimes chemicals/supplements are needed. If/when you have livestock that consumes calcium quickly - you may need to supplement calcium. Sometimes alkalinity is low/high and needs to be adjusted by adding buffers. Sometimes pH is fluctuating and needs to be corrected. But supplements like strontium, iodine (which can be problematic and catastrophic when overdosed) are not needed when regular water changes are done. And should certainly never be added if the hobbyist isn't testing for them and comparing the test results to what is considered acceptable NSW levels.
Tom
