How long do rocks stay contaminated? (if they are)

[spiff]

I have a question. I have been accumulating lots of rock off free-cycle for my tank. All of the rocks I took look awesome, as they've all been used as landscaping rocks and are of interesting formations.

How much should I worry about any chemicals on/in these rocks from being in peoples yards? Who know what kind of herbicides and/or pesticides might have been sprayed on them or God knows what else. The people I got them from said they weren't sprayed, "as far as they know". None of these people were the original owners of the properties. But it sounds like these rocks had a least 3-5 years of weathering with out chemical exposure.

If they ever were sprayed, do you think 5 years of sitting in the weather is enough to flush/break down anything that might have been sprayed on them?

The rock pile I have is huge. I wouldn't be interested in coating them with anything as a previous poster inquired about.
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[cassharper]

who knows. The decomp for pesticides is vastly different per chemical compound and even brand.

Just powerwash it real well.

 

[cchhcc]

I agree.... Just pressure wash them, and don't worry too much. If you just can't stop thinking about it, you can run the filters with some PolyFilter or Purigen to get rid of any residual chemicals (that won't be there!).

 

[cudamaster13]

i have rocks in my south american freshwater tank that i got from the beach and i cleaned my bathtub out and i filled it up with hot water and got a uncontaminated brush and put the rocks in the hot water in the tub and started scrubing alot and i put the rocks in hot water and scrubed for about eight days then i rinsed them off and now there in my tank with no problems

 

[Slim2634]

I got some out of a creek that have probably been there forever. They were black with algae matter and when i powerwashed them they ended up whitish gray. They are in my tank now with no ill effects. I wouldn't worry about the chemicals just powerwash it real well and soak them in your bathtub. I was worried about parasites etc. and everything has been fine.