Obviously RO water + good quality salt seems like the best way to go to ensure consistent water quality. I used to get RO water from my local F&V but they have stopped the service so now need to drive 30mins to my nearest LFS. I am a member of the Two Oceans Aquarium and also live 100m from the beach so have always considered the option of using NSW. Looking at various threads i can't seem to get handle on whether it is a good idea or not? Some threads seem to indicate possible high phosphate levels for NSW (which won't help my GHA problem) and i couldn't get a definitive view on what happens if you keep NSW for a few weeks (makes sense to collect 100 litres at a time but i only use 25 litres every other week for my nano tank). Any sage advice?