Hi frankwii,
Its martin from sandbanks road, if you need any advise text me on 07588620759, have you got a clarke water pump?
if not you need one as your tds will slowly creep up to the 50,s. I went through a 40/40 once a year till i bought one. Had mine over a year now and tds is still around 10 from 400 tap water. i presume your water pressure in poole is crap too?