New white rocks from PetSmart

[SwimmieSue]

Well I have had my tank going really well for two and a half years with three fish in it. Bought some new rocks to do a seasonal decor change, and cleaned them really well, then set up the tank and put the fish in it. To which within 24 hours they died. I noticed that the alkalinity was higher than normal and I attribute that to The White Stones I purchased at PetSmart which I rinsed three times before putting them into the aquarium (of which I saved water from). So, I purchased two new guppies and they are just huddled at the top in the corner together barely eating for the last 3 days. Do I risk taking them out and starting all over again? Please advise
Thank you in advance. So much for redecorating a tank.

 

[Whitecloudminnowguy09]

Oh nooo!!! Sorry this has happened. What type of rock was it listed as at petsmart? Maybe a live rock that skyrocketed your water parameters...

 

[SwimmieSue]

It was a bag of white substrate that actually was not tumbled marble which is what I have thought it might be but it was actually a rock that had a paint coating on it but it doesn't say that on the bag . I went back to PetSmart and they showed me that they use that White Rock and all of their tanks with no problem but the bag does say rinse it first and it can cause the alkalinity to be high.
But meanwhile these two little yellow guppies are just nuzzling their noses in the corner at the top of the tank and I'm not sure what to do.

 

[raylove]

Sounds like it's definitely the gravel. If it's the one I can see online, the reviews suggest others have had the same problem.
The store probably has a centralised filter so the total volume is huge relative to the amount of gravel. With 3 fish your tank sounds like it might be quite small so the gravel would probably affect pH much more quickly.
I would say use rounded 'standard' aquarium gravel only and avoid fancy colours. That said, more expensive brands are often coated in coloured resin and those are fine if you like that sort of thing.
One thing for certain though, you need to remove that gravel and perform a big water change.
Taking out the old gravel might also have removed a lot of nitrifying bacteria, though hopefully you have a decent filter where most of them will be.
Good luck!

 

[Whitecloudminnowguy09]

Remove it then I would say, and change with a better normal colored gravel.

 

[Donya]

Rarely, things that are meant to be aquarium safe aren't. Occasionally you can get a real rock that has something bad in it as an unexpected mineral inclusion or a bit of plastic that isn't hardened properly etc. It's exceedingly rare but happens (happened to me with a modestly sized aquarium ornament that nuked a tank overnight). A lot of the various colored gravel types are epoxy or something similar.

Definitely worth removing the gravel for now since it can't harm anything to do so (while leaving it in could if it's slowly leaching something). Also if you have any activated carbon, whether as a separate bag in the filter or as part of a pre-made filer insert, run a fresh batch of that after removing the gravel. That can help if something icky leached out of the gravel that you can't test for.

However, this sticks out to me as well:

then set up the tank and put the fish in it

If you replaced the substrate, then you potentally took away part of the biological filtration if the tank had been established for 2+ years with some other material there, and that could be causing you a recycle - which would stress the fish. Did you check ammonia/nitrite levels?

 

[jaylach]

A lot depends on the type of rock. Aragonite is one of the best substrates for a salt tank but will dramatically raise the hardness. Since the new gravel is white/gray, it is quite possible that it could be Aragonite but, since live bearers, such as guppies, like hard water. Still, especially in a small tank, the introduction of Aragonite could drastically change the hardness quickly. ANY sudden change in water conditions can stress/kill fish.