My brother in law has been using these uniseal to attach his aquaponics tanks together. They work great for getting a pipe into a tank.

Visit my Amazon Store to buy a Uniseal:
http://astore.amazon.com/latoho-20

Check out the Land To House website:
http://www.landtohouse.com

See whats coming up before it hits Youtube on my Facebook Page:
  / landtohouse  
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