Question on RO water versus tap water

[dapellegrini]

On the lighting question, you could probably get away with some medium light plants... Do you anything specific in mind?

[czcz]

Doesn't RO take you down to ZERO? Perhaps if you did a 50/50 mix of RO and tap you could take your KH / GH down...

Yes, and mixing tap with RO is a very easy way to lower KH while keeping GH. While Ca and Mg are nutrients, it's been shown time and again that low and stable KH can aid many plants, especially Tonina, Eriocaulon, and some Rotala sp.

When most people talk of soft water plants, it's in regards to KH, not GH. Tom Barr/Plantbrain is one who grows plants in low KH while dosing Mg and Ca (GH). Still others will grow in low to no KH while targeting ratios of Ca and Mg. Fwiw, my preference is to dilute 50% of my moderate hardness tap with 50% RO. This is simply easier for me than reconstituting pure RO.

HTH

[rkilling1]

Originally Posted by czcz

When most people talk of soft water plants, it's in regards to KH, not GH. Tom Barr/Plantbrain is one who grows plants in low KH while dosing Mg and Ca (GH). Still others will grow in low to no KH while targeting ratios of Ca and Mg. Fwiw, my preference is to dilute 50% of my moderate hardness tap with 50% RO. This is simply easier for me than reconstituting pure RO.

HTH

This is something that I am still learning also. There is so much misinformation out there. (some that I continue to spread ) I have quotes from Tom, where he has run tanks with no KH like you mentioned and only buffered them to find out what the CO2 levels where and then unbuffed them. So I guess RO is fine, like you said, as long as you add in Mg and Ca , which are macro nutrients.