What are the best cost effective ways to prevent chain rust?

[Flowrider]

I live 5 km from the ocean (not sure if that's relevant), and I pretty much only mountain bike. After every ride, I hose down and clean my bike.

I wipe them down with a cloth.

After a few days, the ones not ridden have what looks like surface rust appear on the chain.

Do you have any cost-effective remedies to solve this issue?

[enkei]

200m from the ocean here. No rust.

However, I don't mountain bike, only very light gravel riding.

Last time I got home after a reasonably wet and muddy ride, I removed my chain, hosed down my bike, and wiped down the bike and chain. No rust.

Are you using plated chains?

[Flowrider]

Actually, not sure what chains they are. Custom factory chains on a Giant Fathom and Talon, if that helps