That's more about experience sharing. I'm very happy to listen experiences other than mine. Yours is also interesting and not "have to" to anyone as mine. Thank you for sharing. 

I was also very happy to read about Seagull system, that looks better than RO I use. That's the value of sharing. 

Water tank treatment depends from situations and sail style. 

Cruisers, who run watermaker daily, living on board 365 days a year have constant water tank flow, therefore less risk. 

Comuter cruisers like me, leave boat for few moths and have issues with tank cleaning. Marinas water have various issues. Even in Med. France generally very good, Italy, Greece varies a lot especially islands, especially this summer. Not mention pacific, where generally much safer to rely on watermaker.