PLA or PETG for 3D printed hydroponics - that is the question.
You like plants, I like plants and there is one thing almost every plant needs and that is water. Which leads inevitably to the fact, that the planter of your choice should be somewhat resistant to our fellow juice of life. Common available planters fulfill that condition fairly well and there are thousands, if not millions of different types. For 3D printing however this might be an interesting question: Should we use PLA or PETG if we use it as a planter, especially in hydroponics?
And before you ask why not also consider TPU, PP, ABS and all the other filaments? Flexible filaments are somehow out of the game as they are flexible and from my experience the most popular and easy-to-print filaments are PLA and PETG, hence we check them out.
PLA
Let us have a look at PLA. It is basically the vanilla filament when it comes to 3D printing. It comes in almost every color you can imagine and is at the low end of the filament price range. You find the technical details of PLA e.g. here and you should probably only use it in low temperature environments as even dishwashers are too hot for it to handle. One rather strong rumor, that you often encounter it, that PLA is soluble in water. I was not sure if this is true, so I started the experiment with my 3D printed hydroponics in PLA, as well as some internet research. I encountered one TDS, that clearly states PLA is not soluble in water here and also prepared an experiment to try it myself.
PETG
I consider PETG to be the second most used filament in 3D printing. In all honesty, I could not tell the difference if you give me the same parts in PETG and PLA. They almost have the same density and haptics. PETG has a slightly higher temperature resistance, but still does not make it out of the dishwasher alive (I tested that by accident). Also the pricing is quite similar. Here is one of the TDS for PETG, that I found. The similar properties also lead to it being used for similar applications. In contrast to the PLA dissolves in water rumor, for PETG I read mostly the opposite, which is PETG has a high water resistance. Naturally I also printed my hydroponics inserts in PETG to see how it performs.
Personally I prefer PETG, because I have better bed adhesion when printing and the prints usually come out in a better quality. That is just personal preference though.
The Experiment
Setting the experiment up was pretty easy.
Print the inserts in PLA/PETG
Add substrate and a plant
Put it in a tin can
Add water
Wait
Repeat 4. and 5. until you the plant are big enough to consider the experiment over
All of the above you find illustrated in this awesome video:
The result
The result? I could literally not find any difference between PLA and PETG. Both planters looked like they are new, the plants grew the same, if I had not made the prints in different colors I would probably have not been able to tell them apart. So for your next hydroponics project just take the filament you like best!
But is it food safe?
Still it is a valid question, if you should use PLA or PETG as a planter for edible plants. Most TDS state, that PLA/PETG is not suitable used for in-vivo applications or be in food contact. While there are certain PLA and PETG filaments, that come with a food grade certificate, the main issue is not the filament itself, but rather the fact, that it is 3D printed. The layered structures allow bacteria to grow more easily and as it does not withstand temperatures higher than 50°C/60°C you cannot clean it hot enough to kill most of the germs. So even with a food grade certificate, there are other limiting factors.
Fortunately our application is not in-vivo (which means in a medical sense inside of a living organism) and also not in direct food contact (at least if you do not want to eat the roots). So from my research it is a clear yesn't. I could not find any reliable source, that proves either side.
Thank you very much for reading and making it to the end of this article. If you want your very own 3D printed hydroponics kit or the STL files to print it yourself, check out my store.