tar in tank - Please help

[reeflooker]

I purchased some Fiji LR and and Nature's Ocean bio sand from a LFS today. After installing, I noticed a black 1" rock protruding from the sand. After removing and testing, I determined that it was tar. WHAT SHOULD I DO.....
The LFS says there is no way tar could be in the LR unless someone put it there. LFS says if I removed it I should be ok. However, I feel that if found 1 piece of tar, there is probable more I havent found.
I currenly have about 50 lbs of LR and 90lbs of sand in a 90 gal. No livestock or corals yet. All materials were purchased from the same LFS.
Should I demand credit and start over or should I just let it cycle as the LFS advises? If I start over, how do I know it will not happen again? Has any one else had this problem?

 

[dad]

This is going to be a personal call on your part. How well you trust your lfs ?
Since you only found one?/ I would probly go ahead and leave everything stand as is.
I would take a net of sort and sift through the rest of the sand and see if you find any more just for personal confidence.
HTH,

 

[reeflooker]

I looked very carefully for more tar...couldnt find any. I think I'm just going to let it cycle...

 

[crispcritr]

are you sure its tar. i had live rock that had black tar looking stuff on it before, it was dead coral and other dead stuff stuck together. it smelled really bad. looked just like tar, but i was not. i just removed it by scrapping it off and cycled it. looks great now.

 

[reeflooker]

I put a few drops of gasoline on the tar. I rubbed it with my fingers and its definately tar.