Reef Safe Plastics

[cope413]

Hi Randy,

I am in the 3D printing industry and have begun printing things for my tanks.

I printed my overflow box. I used ABS, but before installing it and starting my tank, I put it in a 5g bucket and let it cycle in RODI for a couple weeks - just to make sure that anything that could/might leach from it was gone. It's been 10 months since I installed it and my tank is thriving, so I'm assuming what I did with ABS was safe/effective.

This may have been unnecessary, though, and I'd like to begin printing some pieces to attach corals too and to place clams on so that they can attach.

PLA is a common material, but I'm worried it will breakdown or break apart fairly quickly in a reef environment. Also, because it's corn based, I'm concerned it may leach an organic that will feed something I don't want in my tank.
ABS is an option.
I'm most curious about nylon. Specifically nylon 6 or nylon 6/9, because they are extremely durable and non-reactive.

Very interested to hear what you suggest and what chemistry comes into play.

Thanks in advance for your time and help.

Cheers

 

[Randy Holmes-Farley]

You can print nylon? I didn't know that.

Anyway, nylon 6 and 6,9 should be fine.

By PLA do you mean polylactide? It will degrade over time, like biopellets.

ABS is OK by itself, but as with many plastics, it is the things that might be in it besides the polymer itself that could be a concern.

That said, I used an ABS refugium for many years.

Do you have a list of other possibilities? I know polymers very well, but not 3D printing.

 

[cope413]

ah yes, forgot that PLA was ambiguous. Polylactide / Polylactic acid

And yes, we can print in a bunch of different nylon polymers... with more being introduced all the time.

I'm with MatterHackers and we currently offer about 20 different filaments. Some we produce, and some we resell:

PLA
Soft PLA
ABS
Bendlay (optically clear modified ABS)
TPE (NinjaFlex) (thermoplastic elastomer - proprietary, so exact chemistry unknown)
Nylon 6/12
A modified PET (Polyethylene terephthalate)
Polycarbonate (PC)
Laywood (PLA with added wood fibers)
Laybrick - (PLA with added mineral fillers, like milled limestone and calcite)
HIPS - high impact polystyrene
PVA - polyvinyl alcohol, not acetate
PC-ABS blend
Carbon fiber reinforced PLA
Bronzefill - 80% bronze, 20% PLA
TPU - thermoplastic urethane

I'd be happy to print you a few things if you'd like to look/test something.

I've printed a working skimmer out of ABS, canopy hinges for an aquapod, light mounts, overflows, bulkheads, and return lines/nozzles

I think there's a ton of other things that could be wildly useful in the hobby. Just need to have an understanding of the safety of the materials when it comes to our tanks.

 

[zesty]

By PLA do you mean polylactide? It will degrade over time, like biopellets.

ABS is OK by itself, but as with many plastics, it is the things that might be in it besides the polymer itself that could be a concern.

Do you have a list of other possibilities? I know polymers very well, but not 3D printing.

With ABS (and the FDM tech) there are 2 different types of support material. One is a breakaway support, one is a soluble polymer support. That soluble support takes a sodium hydroxide solution to rinse off the support material. That's my guess why the OP let it soak in RO/DI water...

As for what materials you can print... what materials can you name. Just for the Fortus machine I was looking at, there is
ABS-M30
ABSplus-P430
ABS-ESD7
ABS-M30i
ABSi
PC-ABS
PC
PC-ISO
Ultem 9085
PPSF/PPSU

But you can print flexible parts, mold over parts, clear tinted parts (I saw a guy wearing all yellow sunglasses that were entirely 3D printed, lenses included) it's endless and it's going to take over the medical field first (IMO) and then it's just going to grow grow grow after that.

 

[zesty]

Cope, you beat me to it! haha!

 

[Randy Holmes-Farley]

Of all the things listed in both posts, several are probably fine, but I think nylon would be a fine choice for most things.

Polycarbonate may be OK, but not if exposed to high pH, such as limewater/kalkwasser. PET may be similar.

The ABS is probably OK.

Polystyrene should be OK.

Definitely avoid the Bronzefill (copper), polyvinylalcohol (dissolves), pla (may slowly dissolve with or without bacterial action).

 

[cope413]

Yeah, I was just listing everything, not everything I'd consider using in the tank.

Hadn't considered HIPS because it's usually just printed as dissolvable support material.

If it makes any difference, the specific PET polymer has received FDA approval and food-safe.

I think I'll give the HIPS a shot because nylon is very tough to get any glue to adhere to.

Thanks for the input.

 

[Randy Holmes-Farley]

I'm curious, how does nylon get printed? Is it dissolved in a solvent? If so, which solvent?

 

[cope413]

Nope. Extruded at 250-260C.

There are no consumer-safe solvents of nylon that I'm aware of. If you know of one, I'd love to get my hands on some. Not really interested in messing around with phenol...

 

[Randy Holmes-Farley]

Thanks. That's why I was asking!

 

[Daniel@R2R]

I want to see pics of the stuff you've printed for your tank! Could you post some up? Cool info! Btw...everyone in this thread is WAY smarter than I am! LOL

 

[cope413]

I'll try to get some pics for you in the next day or so.

 

[drewsteriam5]

If the PLA breaks down will it actually cause problems with the tank? I've had some frag plugs printed in PLA sitting in my tank for a month now and nothing has changed. I'm fine with them breaking down as long as they aren't going to cause water issues.

 

[cope413]

It probably depends on the exact formulation of the PLA you used, but I would guess it wouldn't cause a big issue, if any at all.

Randy probably has more information on that.


Here's a pic of my printed overflow box in ABS.
I installed it in late June and there's s decent amount of coralline algae beginning to grow on it (all the spots of discoloration are the coralline), so that's a good sign for its long-term viability in a reef tank.
I printed it, then used acetone to smooth the layers together to ensure it was water tight. Then soaked it in RODI for a couple weeks just to make sure there wasn't going to be any leeching.

Half my fish decided they wanted to be in the shot, so that was nice of them.

 

[Randy Holmes-Farley]

If the PLA breaks down will it actually cause problems with the tank? I've had some frag plugs printed in PLA sitting in my tank for a month now and nothing has changed. I'm fine with them breaking down as long as they aren't going to cause water issues.

Not a concern. The monomers released from PLA would be nontoxic and might have a similar effect to biopellets, although the degradation rate will be very dependent on molecular weight and crystallinity.

FWIW, I have used it to design implants to release drugs in people.

 

[cope413]

I believe this is the most common PLA in the 3d printing world.

1,4-Dioxane-2,5-dione, 3,6-dimethyl-, (3R,6R)-, polymer with rel-(3R,6S)-3,6-dimethyl-1,4-dioxane-2,5-dione and (3S,6S)-3,6-dimethyl-1,4-dioxane-2,5-dione

 

[Randy Holmes-Farley]

I would never call it that. It is easier to draw it or just call it polylactide.

 

[cope413]

One more polymer question...

polyhydroxyalkanoate (PHA). It's being blended with PLA in some filaments. Any issues with that one?

 

[Randy Holmes-Farley]

One more polymer question...

polyhydroxyalkanoate (PHA). It's being blended with PLA in some filaments. Any issues with that one?

That's a broad class the includes the ingredients in commercial biopellets as well as PLA and many others.

Biodegradable, but not a tox concern.

 

[drewsteriam5]

I don't know much about biopellets, but could they be 3d printed in PLA? If so could they be designed to be super efficient in terms of the amount of bacteria they can serve?