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Are you concerned about the hose to your tank leaking? What about the rest of your plumbing? Wrap teflon tape around the threads in the direction you will be screwing the connection on three times. Tighten with a wrench. If you are really paranoid, use pipe thread sealant after the teflon tape.

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NO, DO NOT DO THIS!!!

Compression fittings in plumbing must NOT have any teflon tape on the threads. This just causes leaks. Teflon tape is for fittings where the threads are the sealing surface. Compression fittings do not seal with the threads; the threads only provide compressive force.

Also, 'hand-tight' is more than sufficient (in most cases) using compression fittings (not brass but rubber/silicone/Viton, etc). After all, you are dealing with relatively low pressure, which a strong grip exceeds, while a wrench too tight can easily foul the soft seal.

Edit for clarity.

Your comment is what every textbook says and it's not wrong for ideal conditions.

Meanwhile in the field you come across a boogered up fitting line that leaks, you slap some tape on the threads, the nut seals to the ferrule, the ferrule seals to the tube and the tape seals the threads.

It's not "right" but it works well enough often enough that people do it.

Instead of half-assing it, if it's "boogered up" and leaks, the fittings should be replaced.

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