Water questions

[Evan]

I have exceptionally hard and alkaline water coming from the tap. ph 8.1, 12 kh, 16 dGH. I have been keeping some Apistos that can live in moderately hard water by using a 50/50 mix of R/O and tap water.

I would like to start keeping some more demanding species and am considering using pure R/O water but I have a couple of questions I was hoping somebody could answer.

I have two questions:

First, what is the difference between R/O water and DI water? There is one store in my area that sells R/O and another that sells DI. Should I care or should I just be consistent?

Second, if i use pure R/O do I need to reconstitute it with anything for soft water dwarves?

Thanks in advance for any advice you can provide.

 

[tjudy]

DI has had charged particles removed by filtration through a charged media bed. In combination with RO DI will produce very pure water. It will get out very small ion that RO alone will not do. However, DI is not necessary for freshwater aquariums. My RO system produces 3 ppm water from 285 ppm tap. When I use the DI post filter (I have it set up so I can turn the DI on or off) the water comes out 0 ppm.

Water with 0 ppm and 0 KH is very unstable and susceptible to pH swings. I prefer to reconstitute at least a little bit, up to 20 ppm and 1-2 KH. Then I can adjust the pH if necessary and it will be stable. If there is no KH (carbonate hardness) the pH will fluxuate too much.

 

[Evan]

So what about a unit like this which appears to be DI without R/O?

http://www.kentmarine.com/waterfilters/deionizers/deion-200r.htm

 

[beleg]

Hmm. The recharging of the resins is a troublesome job i remember reading.

 

[Mike Wise]

DI systems are typically more expensive to operate over time, compared to R/O systems. The resins are expensive to replace. Those that can be recharged, require dangerous/caustic chemicals in the process.