Using Rainwater

Using Rainwater??


Jim E. Quarles

So you're thinking about using rainwater in your discus tank right? Well it is nice and soft, but just what's in it?

According to the most recent report by the National Water-Quality Assessment Agency, after samples were taken at sixty five randomly selected sites across the United States with a least one sample in each state, the following was found to be in the rain water of most regions tested in at least trace amounts.

Trace amounts to heavy concentrations.

Aluminum, Antimony, Arsenic, Barium, Beryllium, Boron, Cadmium, Chromium, Cobalt, Copper, Iron, Lead, Lithium, Manganese, Mercury, Molybdenum, Nickel, Radium 224, Radium 226, Radium 228, Radon 222, Selenium, Silver, Strontium, Thallium, Uranium, Vanadium, Zinc, Gross Alpha-radioactivity, Gross beta radioactivity.

I ask you, does the above sound like something you would like to add to your discus tanks??

In addition to the Rainwater tests the NAWQA also tested stream bed sediments in the same areas and for a distance of up to fifty miles from the rainwater collection points.

The same elements were found concentrated in a higher percentages then would have normally have been expected.


Then they tested the tissues of fish and clams in those waters. Basically the same elements were found in these tissues with the exception of Radium 224, Radium 226, Radium 228, Radon 222 and no trace of Gross alpha-radioactivity or beta-radioactivity. Also missing was Lithium, the absence of these items can be explained in their chemical or radioactive nature.

Acid rain is reported to be killing trees and forests hundreds of miles from the major source of pollution. There are reported cases of fish being killed in lakes due to acids contained in rainwater.


Of course it can be made safe for aquarium use, but at what cost? And how would you take the required steps or buy the right equipment to provide this task?

Before talking about what is required to remove the heavy metals from rainwater perhaps it should be pointed out that in the tests performed in this study pesticides & herbicides were not even considered nor were the tests design to detect any that were present.

I would venture the statement that rainwater as collected in most locations such as medium to large cities is not fit in its natural state to be used in the culturing of fish of any type.

Dr. Schmidt-Focke told me one time about how he used to collect rain water behind his house in Germany. But he had to start transporting his water from a fairly great distance because the rain in Germany had become so laden with heavy metals and pesticides it was no longer fit to use in his tanks. I am sure this is even more of a problem in the United States now.

With few exceptions all the major hobbyists keeping discus now days use either R.O. units or water treating Resins to remove heavy metals and other undesirable elements from their water supplies.

If you were to design a system to pump your collected rainwater through a R.O. unit or Resin unit I am sure the water would then be acceptable for discus breeding. But then if you avail yourself of such a unit you would be able to use your normally supplied tap water and have no need to collect and store rain water.

I hope this answers the simple question, can you use collected rain water?

Yes of course you can. Is it good water for discus? I think not. I would not advise it. Of course you can collect samples and have them analyzed in your area to find out for sure. This can be expensive but if you plan on using the water it perhaps would be a good investment.

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