[How to deal with rainwater]

Thanks Ira, good to know which protocol you follow as I used the same so far!

 

14 hours ago, Ira said:

Too artificial?  It doesn't get much less artificial than rain water. 

Sorry, I should have been more clear and used "artificial OR miss".
e.g. concrete contains a lot of Aluminum (according to Wikipedia) which may be harmful to fish or my water may miss something for the plants (eg. Potassium).

Also, I think I remember some Forum post about nitrifying bacteria not doing so well in very soft water?

18 hours ago, Ira said:

I do put a few handfuls of coral fingers and rock in my filters because it helps keep the PH from dropping.  But I haven't actually checked the PH in years.

Yes, I fear rapid changes in pH with my low KH and planned to add some shell grit to the filter.

[How to deal with rainwater]

Hi,

I am getting back into the hobby and setting up my first tank. However, I have some trouble dealing with our rainwater supply. I kept east African cichlids back in Europe (15 yrs ago) as our water supply was quite hard (>16 °dH). Since in New Zealand we moved into a rural area and are on tank water stored in concrete tanks (3yrs old). My current water parameters are:

pH 6.8
KH <20ppm
GH <20ppm

Which was fine with me as it opened the possibility to keep all those species that I wasn't able to in Europe (without RO), like Tetras and Corys. Now, I am starting to fear that my water will be too artificial and may miss some necessary components for fish and plants. But there should be plenty of people around this forum facing similar situations!
So should I be concerned and try to blend my water with some water from work (Palmerston North), add some minerals (eg. Seachem, Epsom,...)?

Many Thanks

Chris