Ceramic, porcelain, china, resin, etc

[Alesha]

Which are ok for aquarium decor? How about bisque (unglazed porcelain)?

I've been looking for aquarium decor,  but I want something a little different. How do I know what is tank safe? 

 

[Paul]

They should all be good for aquarium use.

[Alesha]

So sorry I'm just now responding, @Paul.  Thank you for your answer!

Do you know if enameled metal is ok? I'm thinking probably not, but I don't know for sure.

[KoolFish97]

According to many paint/enamel manufacturers most paints are completely inert and harmless once fully cured. 

That doesn't mean all however and that doesn't mean that if they get compromised (scratch, breaks, dents) that issues couldn't arise from the metal underneath. 

To be safe I'd most likely steer clear of things like that unless your absolutely sure of its origins and the impacts it might have on your closed ecosystem.

Also I agree with Paul. Nearly all ceramic should be fine to use (bar maybe some tiny amounts of carbonates or other KH/GH/pH buffing changes but they are so minor and can easily be pre-soaked or water changed out. 

[Jessica.]

When I'm not keeping fish (aka my full time job) is in ceramic arts, and I studied glaze chemistry in college. 99.9% of ceramic surfaces are fine, but if something has you concerned, you can do a lemon test to see if it will leach.

Copper is probably the most common thing that will leach. If you have a green or blue glaze that turns pink when you leave a lemon on it for 1/2 hr, it is leaching copper. Occasionally barium will leach also. Rarely lead (because it's almost never used anymore in ceramics, but if you were putting an antique ceramic pre-1950 in your tank, you might worry about lead).

A matte surface is more likely to leach compared to a glossy/glassy surface in ceramics. 

 Ceramic Lemon Test Instruction

Edit to add- Bisque ware will almost always be fine, unless it is a red earthenware that was made with barium. If it's work you're making, you can ask your clay supplier if they have barium in their clay recipe. Barium is nasty stuff, some manufactures put it in to stop surface scumming (aka white buildup of sodium) on greenware in red clays. If it's commercial purchased work, it probably doesn't have barium. 

Edited October 15, 2020 by Jessica.

[Alesha]

@Jessica. thank you so much. That is incredibly helpful! I *had* been looking at antique ceramics, so the lemon test is a great thing to know about. I had no idea.

I think antique ceramics have an incredibly cool look to them, but I think I'll probably go with something newer, as I can't find exactly what I want in the antique ware. My other 2 tanks are very natural, fully planted with rocks and driftwood. I wanted to use something prettier in a little 5-gallon I'm planning to set up soon. 😉 

[Paul]

1 hour ago, akconklin said:

So sorry I'm just now responding, @Paul.  Thank you for your answer!

Do you know if enameled metal is ok? I'm thinking probably not, but I don't know for sure.

I wouldn't trust any enameled metals. They could be made from pot metal which is made of any number of metals melted together (in other words there's no recipe) and then poured into a mold. So there's no telling what effect water will have on it or what effect it will have on fish if chipped or scratched.

Edited October 15, 2020 by Paul

[Wesley]

Thats some great advice you have there @Jessica. I definitely should write that down just in case. Goes to show that different industries can compliment this hobby.

I bought some cheap resin decorations from Aliexpress. Should've just stayed away from them, couple came in broken (who sends that crap in a plastic bag) and almost always the paint started chipping, which was unfortunate.