Deciding Tank Size

[Coyote7]

Hello! I'm new to the hobby and recently purchased a large tank that was assembled in 2005. After some assessment and research I decided that I'm going to replace the original frame. According to my own measurements, my tank is 60x18.25x26 and there are stickers that identify it as a Marineland (formerly Perfecto) 120 gallon. I've found some measurement charts from Marineland that list their 120 gallon tanks with dimensions 60x18x26.
My question is this: is my tank actually 18 inches wide or is it 18.25? This is important! The new frame I'd like to install only supports a tank 18 inches wide. I've measured multiple times with two different measuring tapes and from the very edge of the glass it measures 18.25 inches wide every time. My length and height measurements are spot on, however; they're exactly 60 and 26 inches, respectively. The silicone seals are in good shape and there doesn't appear to be any bowing or warp in the empty tank.
What should I do? Should I trust my manufacturer's specifications and assume the tank is really 18 inches wide exactly? Or should I trust my measurements and regard my tank as slightly more wide at 18.25 inches? I'd like to avoid purchasing a new frame that ends up being 0.25 inches too narrow. I'll attach the Marineland standard tank dimension sheet in case it helps, I'm very sure I have the 120 Gallon Extra High Rectangular Tank.

 

[griss]

I personally would go with my own (your) measurements. If memory serves, most large scale tank manufacturers gave the measurements to the closest inch. So, I'm willing to be your tank is 18.25.

 

[reefing102]

So I have to ask are you measuring the glass or plastic rim? My 65 is 36x18x24 but if I measure the the rim it 36.25x18.25x24.5

That said, I’m my experience, what @griss said is correct. Generally manufacturers go to the closest inch.

 

[kharmaguru]

Is the original frame a solid molded form (which I assume the new one you want is) or is it just angle plastic wrapped around? If the latter you can be reasonably sure the new frame won't fit.

 

[Coyote7]

Thanks for the input, everyone! The current frame is a molded form and I've been measuring from the glass itself, not from the rim of the frame. I think I'll trust my own measurements here and reach out to the frame manufacturer to see if there are any options. Maybe their frames can tolerate some small size differences.