Regular tank chores
Visual examination of the livestock
Take a look at the livestock and make sure that there's not cyanobacteria forming, dead fish, or other indicators of poor tank health. Your eyes and their ability to detect day to day changes are the best monitoring device available.
Visual examination of the mechanics
Take a quick look around the tank, and make sure that there aren't any pools of water forming, powerheads are positioned properly, dosers are dripping, etc.
Wiping off the viewing panels
Every day or every other day, the viewing panels should be gently wiped down with an alage pad. Daily maintenance will ensure that purple coralline alage, diatom algae and other nuisance algae do not build up. For those who have acrylic tanks, be careful that sand, tiny snails or other abrasize object do not get between the alage pad and the viewing panel.
Topping off with DI water
The water level in the sump should remain as stationary as possible. Without some form of automatic top-off or dosing system, the water level will fluctuate. The addition of top-off water should be done relatively slowly, so as to not dilute the sump too quickly. Of course, too quickly depends on a lot of factors like flow through the sump, volume of water in the sump, and volume of the entire system.
One gallon of freshwater in 10 gallons of salt water has ten times the dilution factor as one gallon in 100. The best advice is to add slowly.
Once or twice a week the skimmer collection cup should be emptied.
Scrape off any algae growth that may have gotten away from you.
Anybody who's ever owned a fish tank knows that about once or twice per month a water change should be performed. Fortunately, for reef systems that don't have too many fish, a ten percent water change once per month seems to work well for most.
Big tanks equal big water changes. For those who wish to get large tanks, ten percent of 180 gallons is nothing to sneeze at. You're swapping out 144 pounds of water there, big boy! The 300 plus gallon tanks sizes typically have dedicated rooms to house the sump, as well as access to drains in order to facilitate water changes and top off.
Powerheads should be removed from the tank, and soaked in distilled white vinegar. Purple coralline alage should begin to detach from the surfaces of the power head. A plastic scraper or credit card can be used to remove any stubborn coraline. After the vinegar cleansing, run fresh water through the pump to remove/dilute any excess vinegar.
The external pumps should have their seals checked for leaks, and should have distilled white vinegar run through them for an hour in order to remove any debris on the impellers. After the vinegar cleansing, run fresh water through the pump to remove/dilute any excess vinegar.