Yes it would be easier and cheaper. However if you want to enjoy a SW tank, making a good initial investment in a 55g, with good lighting, 40+lbs of GOOD live rock, 30-45lbs of GOOD live sand, some good powerheads, and a protien skimmer will make your life easier. Most people give up on SW tanks because they are all maintnance. That is not always the case. But if you cheap out, it can be a bad expierence.
To find sealed resonance
resolve Vas/28.32 =
result of that divided by Vb( box volume)
result of that +1
square root that result
result of that multiplied by FS