... they smelt like chemicals after I soaked them in hot water!
I don't even know if I can even trust stuff that claims to be 'aquarium safe' anymore. I've been using them for a week before discovering this, luckily I'm cycling this tank separately now. But since I've had plants and terracotta in them, what should I do with those? I'd hate to throw them away, but I suspect that not much has leeched into them, the plants are growing beautifully in the short week they where in with the gravel.
Next time I'll go for the slightly pricier glass ones... those actually look a lot nicer and are less chunky.