How are tanks measured for gallons? Include or exclude glass?

[bitterman]

I was wondering I her different people talking about the size of tanks, Does the size include the glass?

My 60"x24"x31" tank comes out to about 195 gallons if you include the glass, but abotu 172 if you take the glass outa the equasion.

Whats correct? Artw keeps calling my tank a 195.

I measured a 75 in the store and it appears to include the glass, so they really arn't a 75.

Thanks,
   Bruce

[groan]

would it really make that much of a difference if you include the glass?
i would think it might if your glass were inches thick...but in the sizes we play with?

[groan]

suing the calculator you get 193.25 shich for all intents and purposes is a 195 ni marketing terms.

[beowulf]

would it really make that much of a difference if you include the glass?
i would think it might if your glass were inches thick...but in the sizes we play with?

I was thinking the same thing.  Glass is what xx mm in thinkness don't see how it can make such a difference.

[bitterman]

Well I get 172.37 Us Gallons without the glass (58.5x22.5x30.25) Glass is 3/4" thick in this tank.

Bruce

[BigDaddy]

Well.. the whole point is SUPPOSED to be about reporting how much water the tank actually holds.  However, as was pointed out... marketing being what it is it sounds better when Hagen sells you a 77 gallon tank that's the exact same measurements as an All-Glass 75 gallon tank (they are both 48 x 18 x 21).  Then there's the easy factor... its easy to remember tank sizes in units of 5's and 10's... thus the 75 that isn't "really" a 75.

And thickness of material can make a difference.  Think about a custom acrylic tank with 1/2" or 3/4" panes... in a large footprint the amount of material that would "displace" the water could be substantial.

72 x 18 x 24 is a 135 gallon tank.  Let's shave off 1/2 inch on each sides for an abnormally thicker acrylic pane compared to a 3/8" glass pane (just an example) and now the tank is only 127 gallons.  Not quite 10 gallons... but still a big difference... that's an extra 1/4tsp of water conditioner you'd need to use (or not use).

[groan]

wow, that's a huge difference.

I guess you're right. it does make a big diff when you get to the larger tanks.

I would go with your second answer in that case.

[bitterman]

Hee Hee I'm going to start calling it a 195, it sounds better and its bigger LOL (call it false advertising, but bigger sounds better LOL)

Since I have well water not worry about water conditioner

Bruce

[AdamR]

Other places that make the difference:
1. When measuring the outside of the tank most people include the frame top to bottom, anyone every fill to the very top?
2. My glass tanks have a gap between the bottom pane and the stand, 1/2 inch there adds up quick in a bigger tank.

AdamR

[artw]

well sure, its easier to sell a "195 gallon" tank than a "172 gallon" tank. Manufacturers like to have standard sizes.  Its the same reason why a 2x4 is not really 2"x4".   its called Nominal sizes

[babblefish1960]

Nominal hits it on the head nicely, as does marketing ploys. The other thing that we need to remember here, is that before adoption of the metric system, we used Imperial weights and measures, very different from what the U.S. use. When you do your calculations in Imperial gallons, it sounds disappointing, yet metric litres sound absurd, so the American system was made universal simply by volume of usage and proximity to our great but easily swayed land.

It is often wise to calculate what volume of water you actually carry, as so many things displace the water, and as we tend not to medicate the larger tanks, it is wise to know what you are in fact dosing.

Otherwise, enjoy the anomaly and brag about your big 90 gallon, or whatever you are sporting.

[beowulf]

So true Babble all that nice rockwork etc brings down the volume of water considerably.

[BigDaddy]

Yup... a 3 inch layer of gravel in the bottom of a 75 or 90 = over 10 gallons of water displaced.  Mind you, there is a bit of water in the gravel.. but if you drained the tank to the substrate line and then seperated the water from the substrate, you'd be lucky to get a 1/2 gallon out of it.  I know... I've done it!

[bitterman]

Now that we are going crazy on things, should we substact the volume the fish take up too? 10 x 12"+ fronts could take up a gallon or two

[BigDaddy]

Good one Bruce  lol