Sizing your system:

Large homes/families typically cater for consumption rate of up to 100 Lm (using an 80w lamp)

Whereas 'mum & dad' can downsize their system to 50 Lm (using a 40w lamp)

Filter sizing:

Standard issue is the 10" Jumbo. 

For very high consumption sites, to ensure filter cartridges last 6 months, 20" filters can be fitted.