I’ve been reading Google results pertaining to using 3D printed materials in aquariums. This is because I’m wanting to print a handheld skimmer designed to scoop duckweed out of one tank to be dumped into my fiance’s turtle tank.
One thing that is consistently said is that PLA is not the best choice because it will break down in water. I am wondering if it will work in this insistence due to the fact the scoop will not be left in water.
Will 2 plunges daily into an aquarium erode the PLA?
I have printed multiple toys for my son in PLA from MakerGear and 3Dmakerworld that he uses in the tub, regularly. They show no sign of degredation so far after about 6 months of his use and abuse.
Awesome, tyvm!
You could also look into an eco-safe, waterproof, spray primer and paint to seal the scoop and make sure it won’t suffer any ill effect
follow up to that: there’s a lot of eco-safe pool sealants, I don’t know if they come in spray can variety (for touchups I would assume) or not
Hmm… I’ll ask my tank guy.
I’ve had a discussion with a manufacturer about this ‘pla degradation’. The conclusion we came to is that it probably could happen if you run your PLA way too hot and if it is originally extruded way too hot (Think super cheap).
PLA is otherwise just fine around water. I don’ think it’s biodegradability comes into play because it evidently needs the heat generated from a composter. I’ve got some prints sitting in aquariums as decorations simply to verify.
Your use isn’t going to be catastrophic if the PLA does fail. The fish go hungry for a while until you notice.
If concerned print in nylon.
Honestly, there was an article a while back - a guy made a water-tight slug trap (filled it with beer) and left it out in the weather/sun for over a year. A year later, he posted how well it was faring, and it was still as strong as ever.
@Richard_Horne has done some experiments on this, from what I hear he has many garden objects that are still going very strong after a lot of exposure.
I have a whole garden full of printed ‘experiments’ some of the items have been outside for 3 years or more now.
And as @Sanjay_Mortimer mentioned I also have a PLA printed water filter and fountain in my outdoor pond ( Glowbug Yellow from Faberdashery) @Andrew_Dent that’s been immersed in water for 15 months, it has gravel filtering in the base and after the water spurts back into the pond through it’s 3D printed nose 
It’s dirty now, but as strong as ever, and still glows at night.
ABS is not holding up so well outdoors, some parts are discolored or have completely changed colour and some are now brittle or already damaged.
I have had Taulman @Tom_Martz 618 Nylon outside for 12+ months, no problems at all, the only thing I have seen is that the tie-dye based prints are now bleached out from the Sun and exposure.
I have concrete covered PLA too, that’s just like solid stone sculptures after 12 months.