Are these pavers safe for my fish tank?

[FreshyNut]

I picked these pavers off the side of the road and thought it would make a great cave for my RTC. If I soak for a couple of days will these be safe for my fish tank? I'm not sure what these kind of pavers are made out of, but I know concrete is not good (which is what I think the large piece is made of). If anyone knows for sure any input is great.

 

[mattison187]

Soak it good, and i bet itll be fine to use. The big tile chunk, make sure there is no glue residue on the back of it though.

 

[FishBeast]

You can drop some muriatic (hydrochloric acid) on it to see if it'll leach out carbonate.

 

[TwoHedWlf]

I think those are all concrete. But concrete isn't necessarily bad anyway, just can increase your PH, but it sounds like those are old thrown out ones, they'll have been out in the rain getting rinsed for years and should be fine for that. Good chance they've been exposed to weed spray though.

 

[FreshyNut]

I think those are all concrete. But concrete isn't necessarily bad anyway, just can increase your PH, but it sounds like those are old thrown out ones, they'll have been out in the rain getting rinsed for years and should be fine for that. Good chance they've been exposed to weed spray though.

Good point. I think with enough soaking it should be ok as far as the weed control. But I was reading online that concrete can dramatically increase pH which worries me because I have an arowana and tire track eel in the tank and they can be sensitive

 

[TwoHedWlf]

But I was reading online that concrete can dramatically increase pH which worries me because I have an arowana and tire track eel in the tank and they can be sensitive

The PH increase fades over time as the lime and cement washes out of the concrete. Like I said, since they're old it's probably been really well rinsed. If you want to be really sure throw them in a big bucket, test the PH and then test it again in a week. If it hasn't risen much, say much more than 1 point, you'll be fine.

 

[Drstrangelove]

I don't know of a way to determine if they would be safe without a chemical composition report on those pavers. Concrete pavers include cement, dyes and aggregate, and when exposed to water (as they typically are when outdoors), they would likely absorb water and water borne chemicals (such as oil, fertilizer, pesticides, salts, metals.) So there's no way to know all of the metals or chemicals are in it.

Simple soaking will remove some things, but soaking may be less effective than it is for removing tannins from wood, and that can take months.

I'd try it for a couple months with fish you aren't terribly attached to, but I tend to err well to the side of safety. Clearly, a RTC, eel or aro wouldn't be anyone's choice for that.

 

[esoxlucius]

I wouldn't put anything in my tank that I wasn't 100% sure about, and for various reasons already mentioned i think it's safe to say you can't be 100% sure about those. If you want to use them that much though i'd boil the hell out of them first and then closely monitor your water/fish until you were happy they were safe.