Copper testing

[zantho]

I've recently received a used tank from a local petstore, it's been washed and scrubbed, and I now have everything I need to get it going as a small reef display tank. Before I put anything in it, I need to test for traces of copper knowing that it could well have been in there. The tank is empty and dry right now, the only thing in there left that could even have copper on/in it is the silicone. So on to my questions:
How long should I let the water sit in there after filling it up before I test for copper? I figure immediately there would be no reading.
How well can copper hide in silicone? Will it be hidden and show up at some unfortunate time in the future or if I get a 0 ppm reading after having water running through it for a few days am I good to go?
If not, will polypads (polyfilters?) do anything? And can I just dump them in there before I add any rock or sand and let the water flow around it?

 

[teen]

if the tank is 75 gallons or less, i would just tear up the silicone and re-bead it. the copper could take a while to leech out, and if it was a DT at a lfs, it most likely had copper in it at one time or another.
you can buy aquarium silicone at your lfs for like $10 at your lfs.
what size tank is it?

 

[zantho]

It's a 33 long. I'm worried that the tank will look terrible if I do that (much like my guest bathroom after I re-grouted). The silicone is black, I know I can get clear aquarium silicone easily. Is it tough to pull it out? Do you redo a corner at a time so it doesn't fall apart?

 

[teen]

i have the a 30 gallon long that i resiliconed last spring (right around this time) it didnt take that long at all.
you just have to have a new razor blade or two (an exacto knife may help) and just peel up all the old silicone. maker sure you get out all the little pieces that are left over though. i used some rubbing alcohol and a papertowel and just wiped everything into the middle then scooped it out. then you just re-bead each side.
i did all the sides at the same time this way all the lines met up perfectly.
after you do this, let it dry for a day or two, then fill the tank with water outside and let it sit for another day or two and make sure theres no leaks.