If Rex did not have the crude language, I would not respect him.

The best set up would be a decent solenoid, Victor regulator, Swagelok needle valve(2 per tank) ADA Ruby check valve bubble counter(these are really cool), ADA diffuser and a reactor.

I'm playing with a reactor and a misting disc.

You can rise the KH as suggested, more water changes. 5 gal vs 10-15 is not much on the tank.

Blast the CO2 out into the sword.

You'll need to pull the sword out in about 3 months because it will outgrow the tank.

Regards,
Tom Barr