After the weekly water change, any leftover or dirty equipment must be cleaned before it’s put to use again. All of the equipment should be brought to a dedicated cleaning space and thoroughly cleaned. Even though it may look clean, thoroughly sanitizing your equipment is critical to maintaining a contamination-free environment.
Generally, the cleaning and sterilization of all of your equipment in the nursery can be boiled down to four steps: scrub, sterilize, neutralize, and rinse. These steps differ slightly depending on what you are working with but are all imperative. Scrubbing helps to remove excess biomass or biofilm from the surfaces and allows for the sterilization to reach all the nooks and crannies. If something has a heavy biofilm, which can easily build up over the course of a nursery season, bleach may not penetrate through the film. Sterilization can be done using bleach, ethanol, steam, or UV; the method depends highly on intended use and space constraints. If you are sterilizing using bleach, it is important to neutralize using sodium thiosulfate. Rinsing with sterile seawater is important to make sure no residual chemicals are left on your equipment. Tank systems and cultures can be delicate and excess chemicals can have drastic impacts. Depending on your operations, there are a few ways to sterilize equipment after scrubbing and rinsing it:
Bleach bath
Soak your equipment in a 1% bleach solution bath overnight. After the equipment is done soaking, add sodium thiosulfate to the bleach water bath to neutralize the chlorine. Use chlorine test strips to determine if there is still any chlorine. If it’s taking a lot of sodium thiosulfate to neutralize, dilute the bath by dumping the bleach solution, refilling the tub with fresh water, and repeating the neutralizing process. Then, rinse the equipment with reverse osmosis or deionized fresh water, and allow the equipment to fully dry to assure there is no remaining chlorine.
Autoclave
Only equipment that is labeled autoclavable by its manufacturer can be put in an autoclave.
These machines are expensive but if you have access to one, it is a very dependable option. The high levels of steam and pressure will thoroughly sterilize all equipment.
Ethanol
Ethanol is great for cleaning surfaces of small equipment, but shouldn’t be the sole tactic for cleaning your tanks. It can be used as a quick kill step to spray and wipe down your tanks with ethanol right before putting them to use.
Use ethanol that is at least 70% in concentration. It can be helpful to put this solution in a labeled spray bottle to easily spritz and wipe off equipment.
Removable equipment from a tank awaiting its weekly bleach bath.
