# water volume: 55 vs 40b

845 Views 8 Replies 4 Participants Last post by  NateFank
last night I "upgraded" to a 40b over the existing 55 due to location it was being placed as well as nicer dimensions.

In doing the switch I used all the water, substrate, plants, driftwood, filter and heater from the 55. I just previously placed that tank there with water level right below the rim.

Now after placing everything was placed in the 40b, the only remaining thing was a 6gal ace hardware bucket not even filled all the way.

I always knew the listed gallons were not exact but damn, water. Volume is no longer a pro IMHO anymore for the 55 over a 40b. I honestly didn't have any more excess water laying around.
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I read here that 40b's are actually around 45gals. Not sure how accurate that was.

But I think 40b's are way better than 55s. So much wider. It's awesome.

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I just did the math and a 40B is actually 47 gallons. I actually didn't know it was 47 gallons. Why don't they call it like a 45 gal?
math proves this false.

55g is 48x12x21 =12096 cubic inches.
40b is 36x18x16 =10368 cubic inches.

they are pretty close but the 55 is def more volume.
231 cubic inches in a gallon so its actuly about 52 gallons and 44 gallons
A 40B is actually 36x18x17 which equals 11016 cubic inches. Divided by 231 equals 47.688 gallons. I just measured my 40B to make sure the dimensions were correct. If you really wanna be picky you could take off 3/8 th's of an inch off the height, for the inside lip of the rim where you would actually fill the tank to.
Oh well I got dimensions from a tank size chart on another site, but yeah you get the idea. In summary 40b are nice tanks
Top tier!
Why are they called 40 gallon breeders if they are closer to 45-47 gallons? Why not 45 breeder? I actually thought it was 40 gallons till I read this post and did the math
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