Right water for my plants...(long)

[GobyGuy5]

I'd just ordered plants online, and am expecting them in about a week, but after checking my water's hardness (don't ask me why I didn't do it before...I don't know...) I've discovered a problem. :(

My water is rather unusual. It's well water that goes through a water softener first. It's pH straight out of the tap is just above 8, and it's KH is 20.5 degrees dH. Our house has an RO unit for drinking, and the pH that comes from that is about 6.5, and the KH is 0. Seeing that my pH and KH was kind of high for plants, I was planning on mixing 2/3 RO water with tap water which would give me an ideal pH of 7 or so, and a KH of 7, which would suit most plants fine. However, I have another problem to solve, my GH is close to zero either from the tap or RO unit. It is my understanding that plants need certain minerals in their water to grow, so I was wondering what I should do to fix this problem. I'm going to get some Tangiyakan Chiclids soon, and was planning on adding some of Seachem's Tangiyakan Buffer to their tank water. I thought maybe I could add small amounts of this to my planted tank's water to solve this problem, would this be an acceptable solution, or should I do something else?

My plant stocking list is:

(ordered)
Hygrophilia
Dwarf Sag.
Ozelot Sword
Jungle Vallisneria
Duckweed

(already have)
Java Fern
Banana Plant

Also, while I'm asking what fertilizers should I use to optimize my plant growth? I'll be working with around 1.5 watts/gallon.

Further Notes:
Aquarium gravel is a natural, pea-sized gravel with laterite mixed into it

The Aquarium I'm dealling with is a 15 gallon, (24"X12"X12")

Thanks in advance, AC is great :)

[Pink Pat]

GobyGuy5,

Detailing all of the particulars you have mentioned would take me all day to type out (I'm not a good typist at all), but the short andswer, and one that would work quite well, would be to simply take you water before the water softener. You are simply removing all that your fish need and replacing it with salt. Since you are going to be keeping Tangiyakan chiclids (which I think is going to be tough enough with plants) you are going to need (want) the higher pH of the tap water, the GH for the plants and the KH to keep the pH steady.

PS. Your plants really don't care much about pH and they care about GH only to the point of getting the nutrients necessary.

HTH

PP