pH, KH & GH

[Lynnzer]

With all due respect, this is one of the enduring myths of the hobby.

Very few fish are bred locally, unless you live in the tropics near a fish farm. Local breeders can't compete for prices, and tend to only produce, the easiest, most common fish. How many posters here systematically breed their fish? A few out of thousands.
Plus if you do breed fish, you learn to breed the ones already adapted to your water from the tap. To try otherwise is frustrating, and usually unsuccessful. I've bred a couple of hundred different species over 55 years in the hobby, and only a handful were able to produce the number of fry they would in nature with more than a small variation away from the water hardness they evolved in. Usually, those were the fish no local breeder would sell, because they were easy to breed and the farms could sell them to stores at a fraction of what a local breeder could get.

I must admit that over the past 3 or 4 years I've only managed to breed the likes of mollies and kribs, oh and loads of shrimp, despite giving all the right tank size and in-tank planting to allow others to get going. The water is really on the hard side here and the Ph ain't great either. That's why I'm changing over to either bottled or rainwater. I may have to mix with tapwater to reach the required parameters for some fish though. Nevertheless I am more into this whole water thing that I ever have been and am determined to provide the best breeding conditions as possible.

 

[Essjay]

Unless the bottled water is distilled water, rainwater and bottled water will have different chemistry. Changing from one to the other and back again is not good for fish, they require stable water chemistry. Unless you can guarantee you'll have rainwater available at all times, I would stay with bottled water - and the same brand of bottled water.

The pH is likely to have been below 7.0 in rainwater as CO2 in the air dissolves in it as it falls. I am surprised at the GH though - how did the rain dissolve calcium and magnesium as it fell?

 

[Deleted member 149562]

I have often wondered about using rainwater, however with the chances of pollutants being present even in the most minute amounts...either from buildings, vegetation or someone having a fire nearby or factory output etc...I have shelved the idea and stayed with the bottled water.

You can't always test for everything such as pesticides, heavy metals that might be in the rainwater. Whether living in a rural setting or an inner city area, there is always going to be pollutants of some sort that gets into the rainwater somehow.