I posted a thread about 2 weeks ago about the amount of gallons of water the 29 bio cube actually holds and I was just testing the new tank and it only held 22-23 gallons of water. This was an empty tank. I sent an e-mail to Oceanic and received a reply today. I am told that the 8,14,29 bio cubes do not mean that this is how many gallons of water they hold. It was just a designation. He stated that the 29 bio cube is actually a 23 gallon tank. Sure wish I knew this before I purchased it. I would have gone a different route!