GatorHunter Posted January 25, 2009 Share Posted January 25, 2009 Hello, Trying to find out how to calculate weight of a 29 gallon with sand and rock inside w/ water. I can weigh the rock and sand easy but the entire weight with water isnt so easy for me and now that I am looking at stands pre made and the one I want says no more than 290lbs. So if someone has any idea of what I am looking at let me know. Thanks, -Gator Link to comment
Kraylen Posted January 25, 2009 Share Posted January 25, 2009 a gallon of salt water weighs 8.556 lbs Link to comment
Codeman Posted January 25, 2009 Share Posted January 25, 2009 Remember that all the rock and sand will displace some water. I think you should be in the clear. Link to comment
neanderthalman Posted January 25, 2009 Share Posted January 25, 2009 A gallon of salt water weighs about 8.5lbs 29 gallons is about 246.5lbs Add in the tank weight and the rock, as well as your lighting (hood), and you're probably over 290lbs. Link to comment
Marteen Posted January 25, 2009 Share Posted January 25, 2009 Remember to calculate water displacement by your rocks and equipment. A BC29 when filled with rock and sand probably holds close to 22-23 gallons of water. The baffles and rear wall take up a lot more room than you would think gallon wise. Link to comment
MitchReef Posted January 25, 2009 Share Posted January 25, 2009 You would NOT remove weight due to rock displacement as you are not just taking the water out, you are obviously putting something even HEAVIER than the water in, to displace it. If the water was being displaced and the rock, etc, didn't weigh more, then it would float. Therefore, the weight of the total volume of water is actually an underestimation.... Link to comment
Scott Riemer Posted January 25, 2009 Share Posted January 25, 2009 You would NOT remove weight due to rock displacement as you are not just taking the water out, you are obviously putting something even HEAVIER than the water in, to displace it. If the water was being displaced and the rock, etc, didn't weigh more, then it would float. Therefore, the weight of the total volume of water is actually an underestimation.... 10-4, but you don't estimate for 29 gallons plus rock and sand weight since there won't be 29 gallons of water. That being said, better to guesstimate high, IMO. Link to comment
neanderthalman Posted January 25, 2009 Share Posted January 25, 2009 10-4, but you don't estimate for 29 gallons plus rock and sand weight since there won't be 29 gallons of water. That being said, better to guesstimate high, IMO. precisely. Also, the displacement won't be much. Maybe four gallons or so, IME Link to comment
MitchReef Posted January 25, 2009 Share Posted January 25, 2009 I thought everybody was saying that the weight would be less, due to the displacement of the water...I just wanted to be sure, cause some folks don't do the 1+1, they just take a statement for what is said... Thanks for the clarification... Link to comment
Codeman Posted January 25, 2009 Share Posted January 25, 2009 Well, shouldn't a stand for a 29 gallon be rated for the actual weight of a full 29 gallon tank? Link to comment
Scott Riemer Posted January 25, 2009 Share Posted January 25, 2009 Well, shouldn't a stand for a 29 gallon be rated for the actual weight of a full 29 gallon tank? You would think. Link to comment
neanderthalman Posted January 26, 2009 Share Posted January 26, 2009 You would think. They probably estimated the weight of a 29 gallon at 290lbs, and then prescribed that as the limit. That's ballpark what we're seeing... Makes sense, right? Link to comment
Scott Riemer Posted January 26, 2009 Share Posted January 26, 2009 They probably estimated the weight of a 29 gallon at 290lbs, and then prescribed that as the limit. That's ballpark what we're seeing... Makes sense, right? Either that or lawyers are involved. In other words, CYA with a weight limit in case something goes wrong. Link to comment
GatorHunter Posted January 26, 2009 Author Share Posted January 26, 2009 Wow, Yea it doesnt make sense I understand the water rock ratio as rocks are solid and they ad volume to the water but at the same time weight. I guess I will just have to build a stand out of concreate. I guess if I load it down with rock and 1" or 2" of gravel well see what happens. I think I already have 20 or 25lbs of rock in my tank and atleast 10lbs of gravel. Havent transfered to the new stand yet probably later today. I think the tank once I add more rock and gravel as I intend to do will weigh like 300 something. Link to comment
OB1 Posted January 26, 2009 Share Posted January 26, 2009 Just to put the rock displacement into perspective.... I just added 7-lbs live rock to a small tank. I removed less than 1/2-gallon of to get the level back to the same as it was before. 7-lbs rock minus 4-lbs water equals 3-lbs gained weight. Link to comment
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