Glad I could help. If you want to keep it simple, my suggestion is water changes, a low to moderate coral load, and weekly chemistry testing. Skimmers CAN pull calcium and stronium from the water, but they do it so slowly that you wont really notice it if you do regular water changes and keep your salinity where it should be. From my own personal experience, I have 15 different coral colonies ranging in size from frags to full-blown adults in my 45gallon w/sump. I test my water parameters for pH, alkalinity (KH), calcium, nitrate, magnesium, and phosphate. About 3 times in two months I've had to add a little calcium supplimentation to keep levels where they should be. I try to run no less than 410ppm of calcium in my reef and a dKH of no less than 10. Water changes have kept the alk at 10-11dKH and when my calc drops to 420, I put a little home-made calcium chloride addative in there to kick it back up to 420. Hasvent had to dose magnesium ever either. Phosphates and nitrates are monitored just to double check for nasty bilological events, and if I do detect phosphate, I drop a knee-high stocking full of phosphate binder in to remove it (couple hours usually). I do weekly ~10% water changes of 5 gallons using Reef Crystals salt. It's pretty maintenance free and simple. Definitely what I'd reccomend for all first-timers
Edit: I'm a chem buff now?
. The only reason calc, iodine, and stronium are removed is because skimming removes some water along with the nutrients. SO you are technically removing SOME of those elements, but its really really negligable. If you never did water changes you'll notice your salinity drops over time with skimming, cause it removes some salt too. But its never anything that aquarists worry about.
And one word on iodine for mushrooms. I dont add a drop of iodine and my shrooms are taking over parts of my tank... Take that for what its worth
Finally, make SURE you take your chemistry readings at the same time of the day when comparing. ALL chemistry values will fluctuate as the day goes on, but should remain constant at the same time period (provided a consistent lighting cycle) from day-to-day. I could go into the photosynthetic reasons, but I've got a beer and a tube of superglue waiting for me, so just test at the same time everyday