rainwater for tank topup

[revant01]

Has anyone tryed using rainwater as a source of nutrient free water to makeup the volume of water lost through evaporation. The air is clean enough here so i dont have to worry about acid rain or too much pollution. Is there anything else to worry about that would stop the use of rainwater

[aquaman67]

IMO that is probably not a good idea. I would check the pH of your rain water first. Don't be surprised if it's 6 or lower. Also, why would you want to risk adding unknows into your tank? Is it worth saving a few pennies worth of water that may wipe out your tank? Are you sure there is no traces of copper, for example? You are betting there isn't. You may be right, or you may lose everything. Just a thought.

[Pineapple House]

I wouldn't do it. You never know exactly what is in your water. You're much better off if you went with your regular freshwater top off.

PH =)

[revant01]

The water from the taps will most definantly have copper traces in it as i have copper pluming in my house, and i dont have the money to buy a RO DI setup that could get rid of those trace amounts. Besides copper what else would i have to worry about.

I just tested my tap water and it comes out at 7.6 or above
the rain water coming off my roof is currently at 6.4

Has anyone tested the ph of RO DI water before adding it to a tank? It would be interesting as a comparison.

I am just wondering if the low pH is caused by dissolved CO2 in the water. I think ill let a sample sit around for a while and see if the pH rises.

[slipknottin]

acid water (6.4 is slightly acidic) will eat away at the alkalinity of your water if added directly to the tank. It is recommended to add buffer to the water first, and airate it overnight.

[revant01]

I am planning on having a 50 litre container of suitable water connected to an automatic topup system so i wont have to add water as often.