What is the routine maintenance of an inground pool with a salt sytem? 30,000 gallons?

The only difference between this and any other pool is just the salt system itself. Monitor the salinity. Most uints have some sort of display that will tell you what the current salinity is and the status of the cell. If the pool is run year round, pull the cell out every 3 months or so to check it’s condition and clean out any debris or mineral deposits. Most cells are self cleaning by reversing the current, but sometimes stuff builds up and shorts out the cell slats.
If your salinity drops, add the corresponding amount of salt to bring it up into the unit’s comfort zone for operation. They differ a bit by manufacturer so check your manual.
Other than that, keep your chemistry balanced and do your routine maintenance according to the type of filter equipment you have. I can’t be more specific here as there are so many types and you don’t mention what you have.

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