A 240 gallon tank is a lot of wieght. I wouldn’t hesitate to put a 180 or less on what u have, but getting bigger then that would make me think about adding support. Only having a 24” crawl space would probably make my mind up not to do anything being I think it is more then likely ok as it is.
If the house is still pretty level then u probably have a good foundation & the beam isn’t going anywhere. If the house is way out of level then your foundation probably isn’t to great to begin with, so extra support may be a good idea.
If u leave it be I would keep a eye on the tile floor. The grout & even the tile itself would start cracking before anything catastrophic happened to the tank.
If the house is still pretty level then u probably have a good foundation & the beam isn’t going anywhere. If the house is way out of level then your foundation probably isn’t to great to begin with, so extra support may be a good idea.
If u leave it be I would keep a eye on the tile floor. The grout & even the tile itself would start cracking before anything catastrophic happened to the tank.
