What do you guys think of this?

[Dominic]

Right i'm looking for a low-cost way of producing water that is adequate for chocolate gouramis.

I will be using R.O, and either remineralising or mixing the R.O with tap water.

But then I came across this- http://www.ebay.co.uk/itm/API-Tap-W...um-Water-/310787041874?_trksid=p2054897.l4275

It seems like a really good idea, and I like the idea of no waste-water. And saves me making a trip to my LFS to get R.O.

Of course, i will remineralise/mix this water.

What do you guys think?

 

[Rasbora]

Most commercial users have gone over to resin filtration from RO. If you're only using small amounts of water it may be OK but you need to test regularly to make sure the resin is not exhausted (get yourself a TDS meter). If you use much water, you may find resins become an expensive chore.
Thought about using rainwater?

 

[Sacha]

This is not a low cost choice.

There's no point just using DI resin without RO. The DI will become exhausted every couple of weeks, and you'll be buying hundreds of pounds worth of the stuff every year.
If you're worried about waste water, just buy a pumped RO unit with DI. I don't know why you would choose to use solely DI resin

 

[Edvet]

RO units can be had reasonably cheaply nowadays (50€ here in the Netherlands), the rest water can be used for different purposes, watering, pond, even a hard water aquarium.