Tap Water

[Earl Karl]

So I know this is a noob question, but I have a special water source where my tap gets filtered before it comes out, so no chlorine in the water and such. TDS is 200 due to elevated calcium and such. I was always told that you should always use RO water, but I was never told why. All I know that tap causes algae. But what in the tap water causes algae? Is there anything else I know about using tap water?
(I'm still going to use my RO/DI, just wondering)

 

[Randy Holmes-Farley Verified Community Expert]

My main concern is copper, but there can be very high levels of other things such as silicate, phosphate, etc.

I discuss issues with tap water here:

Aquarium Chemistry: Tap Water in Reef Aquaria ? Advanced Aquarist | Aquarist Magazine and Blog
https://web.archive.org/web/20040204053142/http://www.advancedaquarist.com/issues/jan2004/chem.htm