Hi Jason and welcome to our forums !
No one is going to be able to guarantee you that your tank will be algae free.
We can give you advice on husbandry and maintenance techniques which will help you control it. The thing that is usually missing when algae is out of control is a consistent routine of tank maintenance, and an understanding of what triggers algae blooms.
To your question, all of your decorations and gravel can be disinfected with a 19:1 Water/Household Bleach solution. That will kill algae and spores. I am sure you see that a really good rinse will be necessary.
If you have no fish, critters, or plants in the tank you could use an algaecide.
This would require a rinse or water changes to get rid of the chemical when the algae is dead.
Regards,
Jay