hi propole,i have noticed difference with the colour change filters,they use to last about 6 weeks now they are lasting about 3 weeks,maybe ionics are not making enough profit,other people who use ionics system in my erea are also complaing about the cost of running there systems,i beleive there is a market out there for someone to make these filters because at £75 a time including vat it is not cheap,some one from ionics should let people know what is going on,because if someting dodgy is going on they will start to lose custom,ionics please respond