acrylic tank with tiny cracks

[smilla4]

I apologize if this has been asked previously, I did search the forums first before posting, but did not find answers.

I answered an ad in craigslist for a 60g acrylic seaclear tank. When I looked the tank over, I noticed lots of tiny cracks along the edges of the tank, and a two inch patch near the top. I asked at the local LFS where the guy purchased the tank, and the LFS guy said that wide changes in temperature can cause this. He also added that if the cracks didn't go all the way through the acrylic, it was ok. And if it did leak it would be a slow process rather than the whole thing exploding. (I was worried that I'd have 60 gallons of water on my floor).

I didn't buy the tank, but I was wondering about the integrity of acrylic tanks in general. Is this a common occurance?

[TCTFish]

I would guess the internal cracks could continue to grow as more stress of heat fluctuations is placed on the acrylic. I wouldn't buy it either...safe or not...why take the chance? Even a slow leak can be just as disasterous, but may take longer to discover it. Heat fluctuations also affect glass tanks, just the cracks or more external to internal instead of internal to external...so to speak.

The most common downfalls about acrylic tanks are they do scratch very easily (scratches on the outside can be buffed without disturbing the tank, but scratches on the inside require full drainage of the tank) and acrylics can bow over time.

[greenmaji]

sounds like heat glazing..