Here are some suggestions that you,your architect,engineer,builder,etc. might want to consider if you haven't already:
1-----Since this tank is swimming pool sized and as this is a new house, are there any homeowner's insurance issues? Are there any house design and or warranty issues?
For example, the humidity produced by this size tank in the basement will be large and needs to be addressed in the design, so as not to negatively impact the house structure, beams,conduits,hardware,upper floor subflooring,create mold,impact the house warranty, etc etc.
Another example, would be salt water drift if it occurs consistently or splashing which could corrode metal building components and hardware over time.
2-----Estimate the power,water,salt,food and other recurring monthly costs, so that cost models can be created and so that the cost of maintaining the system doesn't surprise you, or cause your family any financial stress that might interfere with the success of your family's investment and enjoyment. Perhaps you know someone within an institution with a comparably sized tank who can supply you with a breakdown of their recurring costs for that particular saltwater aquarium.
3-----As you have a degree in marine biology perhaps there are tax deduction possibilities that can be explored based upon your profession, work or business? If this is possible then paying a qualified tax professional for a written opinion so you could know your options beforehand and plan accordingly might be a wise option.
4-----Run worstcase scenarios,-- for example what happens to the tank, its inhabitants, your house if you go on vacation and the tank leaks while your house is alone? What design solutions and or alarms for example can be designed into it so it mitigates the damage and automatically notifies you or someone else with access who can prevent further damage to the house,biotope and your water bill?
5-----Remember Murphy's law.
6-----Above all remember Safety comes first.
If you are able, please illustrate your project with pictures and narrative.
In any case best wishes to your family and good luck with your new house.