BONECO Aqua Pro 2-in-1 Humidifier Filter A250

I have the 7135 ultrasonic humidifier. with this filter, would i still need to use a silver ionic stick or does this replace that?

I need the boneco demineraliation cartridge 7531. Cant seem to find that anywhere. Could I use this as a substitute?

Test strip showed neither red or green. How can I get a replacement test strip?

Will this fit be compatible with my Air o swiss UC600 humidifier?