i use reef crystals as it mixes up - at sg 1.025.
Table 1. Parameters critical to control in reef aquaria.
this is from randy holmes farley:
Parameter:
Reef Aquaria Recommendation: Typical Surface Ocean Value
Calcium 380-450 ppm : 420 ppm
Alkalinity 2.5-4 meq/L 7-11 dKH : 2.5 meq/L 7 dKH
sg = 1.026 : sg = 1.025-1.027
Temperature 76-83° F : Variable
8.1-8.3 : 8.0-8.3
Magnesium 1250-1350 ppm : 1280 ppm
many people try to maintain alk a bit higher then NSW because it allows a bit of "play" should things go bad but i like to be at about 3 to 3.5 meq/l and Ca around 400 ppm +/- 50, if i test in this range i'm happy. its easier to be stable (which truely is more important) at a little lower levels then trying to maintain elevated levels at a little above NSW - but again this is a IMO thing as you will find others disagree. either way you go stay in randy's recs - they are sound
after your tank is 6 months old and all you need to test is alk and Ca unless there is a problem, and test no more then weekly and you can even start to test less once you get balanced and get a good practice down. i only test my SPS tanks -my softy and fish tanks i don't even test anymore i just try to stick to my water changes, careful observation can be just as effective ie you'll know if something is wrong once you have a feel for your tank
as far as the refuge is concerned you are absolutely correct but it is a semantics arguement. a "true" refuge as the term was originally used is a tank upstream from the display that has a very low flow and is gravity feed back to the tank. it does not neccessarily effect the displays water level though as you suggested, but can in a nano. the original idea was to have a place safe from predation where planktonic foods could reproduce, grow and be added to the tank without having to go through (to quote nemo
"the spinning whorl of death" a pump.
fuges in a sump are actually a version of an algae scrubber where their primary focus is the use of algal growth on an inverted light schedual to reduce nutrients and fluxs in pH. these typically have higher flow then a fuge would need and always have a pump back to the tank. some plankton of course will make it up to the tank. again 2 dif applications to similar ideas. both have important benifits but are not neccessarily a substitute for one another. they are different! a tank without planktonic preditors may not need a true fuge as the plankton reproduces in sufficient quantities in the tank. a tank with a very high bioload of fed fish may need a sump with algae to reduce the nitrates/PO4s.
OK i'm done again........
but as you can tell i enjoy talking reefs so ask away if you want more.........