Can I use a regular aquarium as a saltwater aquarium?

I would like to start a saltwater buy medicine online aquarium but am not sure if I can use a regular aquarium.

 

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Marineland Penguin 660 Power Head 175 gph Works Great Aquarium Fish Tank Pump    US $.99

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50G Aquarium Submersible Glass Heater GH200 200W New    US $16.95

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