

I’m not an expert on this, but I’ve worked with fresh and saltwater aquaria for years and here’s what I can say: food grade plastics should be fine to use, since they are not supposed to break down in water. I 3D print a lot, and PLA is not safe for aquaria because it is made of plant material and biodegrades in water over time, while PETG is generally safe for aquaria – but you have to be careful of what dyes/colors are used, same with ABS and nylon so long as they say ‘food grade’. Fish are pretty tolerant afaik, while invertebrates (especially crustaceans and cnidarians) are typically more sensitive to contaminants. That said, polypropylene (PP), and high density or cross linked polyethylene (HDPE or XLPE) are considered safe so long as they are virgin plastics (not recycled material). The surface and porosity makes a big difference in how long the plastics will last before biofouling – basically, microbes will form a biofilm and eventually other things will start growing on the surface, but periodic cleaning should keep this from building up. Also, keep in mind that each type of plastic has different tolerances to temperature, pH, etc., and the age of the plastic matters.
As an aside, there are micro/nano plastics everywhere. It’s unavoidable at this point. One of the biggest concerns for aquaria is other types of contaminants – other chemicals that are added to plastics (e.g., BPA) and heavy metals used in pumps, heaters, etc. Electronics and their plastic housings eventually fail, surprisingly often and quicker than expected at times, and the stuff that leaches out can cause a lot of harm to the animals, not to mention if a heater cooks the tank or just stops maintaining temp and the animals get too cold.




I think for cuts there’s general rules for location, depth, and length to qualify as an emergency. Deep punctures/stab wounds should always be treated as emergencies, do not remove the object, but stabilize it so it doesn’t cause more damage. An amount of blood equivalent to a can of soda is life threatening.
I’ve stayed current on first aid certifications for about a decade and grew up with a parent in the medical field. I still suck at knowing when something requires an er visit, quite possibly because family, friends, and neighbors would come over and get stitches on our kitchen counter rather than go to the hospital. The best I can say is, if you are questioning whether something requires a hospital visit, then it probably does. Better to be safe than sorry.