Internal tank lining?

[halocline]

Yes, each of the three tanks have relief valves as well drains. We let the compressor go to about 30 pounds and open the drain values in turn. On the next use, we plan on capturing some of the air and have it tested - just for safety and knowledge sakes.

So you are planning to run your compressor at 30PSI? That’s awfully low, I assume I’m not understanding something. Typical 2nd stages on scuba regulators require about 125-140 PSI above ambient to work well. That means if you are down 30 feet, I imagine you’d want to compressor to provide 140-155 PSI to compensate for the depth of the 2nd stage.

I know absolutely nothing about hookah systems so feel free to ignore my comment!