(Source: T. Montgomery from Zebrafish Book 5th Edition)
Siphon (cleaning by "vacuuming") the bottoms of all tanks at leastonce per week. Use siphon tips with a length that corresponds to the size of the tank: tips for 5-gallon tanks are 12" long, the 10-gallon tips are 18" long and the 30-gallon tips are 26" long. Each tip is made of ½" I.D. x 1/16" Wall Plexiglas tubing (Port Plastics, Portland, Oregon). Cover one end with a one inch tip of 3/8" I.D. x 3/32" Wall Amper Latex tubing at one end (VWR Scientific Co.). (See Embryo Collection, for a diagram.) The siphon tips, which are attached to the hoses, are the only parts of this apparatus that can be immersed in the tank. Use each tip in only one tank and then sterilize it by soaking in a bleach solution (solution is 20 parts water to 1 part bleach) followed by a rinse in a pipette washer.
Scrubbing (removal of algae from sides, front, and back of tank) is done on an "as needed" basis. (If you cannot see into the tank, it is past time to scrub.) Make handles from ½" x 1¼" Plexiglas Plastic (Port Plastics, Portland, Oregon). The heads are made by sewing Scotch Brite Pads (United Grocers, Eugene, Oregon) with 20 lb test monofilament fishing line so they slip tightly over the scrubber handles. Use each handle and head assembly in one tank only and then sterilize by bleaching as described above for the siphon. The scrubber heads can be autoclaved. Use two lengths of scrubber handles. The size for 5 and 10 gallon tanks is ½" x 1¼" x 16" and for the 30 gallon tanks use ½" x 1¼" x 24" handles. Heads are the same for both size handles.
Tanks that are emptied of fish need to be cleaned and sterilized before another batch of fish can be introduced. Drain the tank and remove it from the rack. Remove and discard all tape, air pipettes, and siphon tube netting. All other parts (lid, back, and water fittings) are kept with that particular tank. Clean all parts with brushes and a scrub pad. Clean the tank thoroughly with a scrub pad, taking care not to damage the silicon water seals on the inside (algae should be left if very gentle rubbing will not remove it). Once the tank and parts are clean, they need to be sterilized in bleach. Place all parts except the lid into the tank and cover them with about 3" of water. Add 1/4 cup (~65 ml) of bleach to a 10-gallon tank (½ cup to a 30-gallon tank; 1/8 cup to a 5-gallon tank). Wash the bleach water thoroughly around the inside of the tank by hand, using a pad, sponge, tank back, or other means to expose all inside portions of the tank to bleach. Immerse the lid in the bleach water and then place it on top of the tank to trap the fumes inside. Leave the tank overnight. The next day, rinse the tank thoroughlywith tap water and then rinse with dH2O. Allow the tank to dry completely. After drying, reassemble the tank, fill with system water, and let it sit overnight before adding fish.