1. Make any adjustments to the placement of the decorations in your aquarium before you fill up the aquarium all the way. Not doing this can cause an overflow when you reach into the tank.
2. Keep plenty of testing kits on hand, if you own a saltwater aquarium you should mainly focus on nitrates, PH, salinity, and phosphate levels. Never be caught off guard, make sure you have plenty of kits available to test the levels.
3. When adding new species to your aquarium, you have to ease them in. Adding too many fish too quickly can cause the ammonia and chemical levels to raise quickly. Adding fish slowly gives your filter time to catch up.