After getting the tank initially setup, there were a number of things which did not pan out at first.  These included:

On top of that, there were a couple of things that I needed to get dialed in such as:

Bubbles in the tank

I had taken some care with my sump design to put in several baffles to prevent bubbles from getting into my return pumps, but it obviously wasn’t working.  Very small bubbles were being generated on the overflow side and these were small enough that my baffles had no affect on them.  They happily swept through all my baffles, past my settling area and into my return pumps even thought the sump is 4 feet long.  The issue with the bubbles is primarily cosmetic, but they can also cause air pockets to form under shelf type corals and cause areas of die-off.

 I first tried several things that were not very effective.

After looking closer at the problem, it became obvious that the main source of fine bubbles was from the output of my skimmer.  I found that by readjusting my skimmer to have a higher water level in the reaction chamber, the bubbles decreased dramatically on its output and problem was solved!  Way too simple, but effective.

 Excessive overflow noise

 My two MAG 9.5 return pumps output about 1500GPH combined.  This amount of water flow through the overflow and into the sump created quite a racket.  The filter bag on the overflow tubing helped to minimize the rushing noise in the sump as did increasing the water level in the sump.  I had purposely left the overflow tubing above the sump water level to prevent gurgling noise, but I found that placing the output below the water level quieted the noise considerably, reduced splash and did not induce any new noises.  My sump was now quiet, but I was still left with a loud rushing noise through the overflow itself.  Going against conventional wisdom, I decided to add a ball valve to the overflow line.  The idea was to restrict the overflow enough to raise the water level in the overflow box so that it would reduce the waterfall affect.  I slowly closed the valve until the water level started to drop in the sump, which indicated that I had an imbalance between my overflow and my returns.  I then slowly opened the valve just until the water level started to rise again in the sump, meaning that my overflow could handle just a little more water than my return pumps were putting out.  This caused my overflow line to mostly fill with water and quieted the waterfall noise down to almost zero. 

The downside to this approach is that you have somewhat of a balanced state between your overflow and return.  If something upsets this balance, there may be a tendency to run the sump dry.  Normally, you want the overflow to have significantly greater capacity than your returns to prevent any such problems.  I will keep an eye on this arrangement to make sure that it does not induce any new problems.  Simple but effective.

Excessive Temperature

 I had made the decision to run this tank cooler than on my previous tank.  I had been using a temperature range of 80-84 degrees.  I noticed that many of my corals did not seem happy at the higher temperatures, especially xenia.  Also, the best reef tanks I have seen have been run at cooler temperatures of 75-78 degrees even though the current trend is toward higher temps.  I made the decision to try to maintain mine in the range of 78-80F as a compromise.   I built the light hood with 4 muffin fans that blow air in from the back and direct it across the surface of the water.  I discovered that with nowhere for the hot air to go, the tank was getting warmer than I liked, so I made a couple of changes that seemed to fix things.  

These changes have allowed me to keep the temperature within the range I am looking for, but I may eventually invest in a chiller.  We will see how things fare as we get into the hot summer months.  Although the house is air conditioned, the room the tank is in is at one end of the house and it does not get much cross circulation.  Another easy change I will probably make is to add an exhaust fan to the bottom of the tank cabinet to exhaust the warm humid air from around the sump rather than leave an end door open.  I already provided a hole for this purpose, now I just need to add a fan and wire it in.

 Low pH

 This is an area I have never had a problem with before.  The tank runs at about 8.05 -  8.1 during the day and drops to as low as 7.75 at night.  I am using a PinPoint pH meter to monitor it.  While it is normal for the pH to drop at night, I would really like to see it stay above about 8.2 during the day and about 7.9 at night if possible.  

To determine the cause of the low pH, I placed some water in a cup and ran an airstone in it for about 15 minutes.  The pH went from 7.8 to 8.05.  This indicated that the culprit was an excess of CO2, probably partially due to the calcium reactor.  However, switching the calcium reactor off for a night did not seem to have any affect.  I have implemented the following changes:

These two changes increased the pH from about 8.05 to 8.2 within a half day.

Dialing in the skimmer

The skimmer I selected for this tank is a Precision Marine Bullet 2.  This is a high powered skimmer based upon the Beckett air injector rather than a normal venturi value.  These skimmers process much greater amounts of water and air than normal skimmers and are suppose to require less maintenance.  I am powering my skimmer with a MAG18 submersible pump which puts out 1800GPH at zero head.  I initially started with the air intake set to wide open and adjusted the water level in the skimmer reaction chamber to the specified height in the chamber.  I was unsuccessful in getting a reasonable foam with these settings.  Either I got no foam at all, or I was dumping a gallon of wet foam out every hour.  I discovered through trial and error that by adjusting the water level higher in the column and decreasing the amount of air, I achieved smaller, more stable bubbles, which gave me a much better skimming action.  The skimmer now skims about 1 gallon a day, which I consider about ideal for this size of tank. 

 Dialing in the Calcium Reactor

The calcium reactor I selected was a Precision Marine CR622.  This is their larger reactor that holds about 15lbs of media.  Dialing it in was fairly simple.  After setup, I adjusted the output affluent to be a broken stream (between a drip and a steady stream) and set the bubble count to a little more than 1 bubble per second.  This has worked to give me a calcium level of about 500 ppm and alkalinity level of about 4.0 meq/l in this first week of operation.  I will continue to monitor and fine tune the reactor over the next few weeks.