Hi all,

In general i cut 50/50 with tap, sometimes to breed in go 90%.

Same for me. I have a good quality hard tap supply and I use rain-water, so the conductivity of the rain-water is a bit more variable than it would be if I used RO.

I don't add a standard amount of tap water, I just keep the tanks within <"

a conductivity range">.

I use 100% and remineralize using James web site method.

If I didn't have a hard water supply (~18 dKH/dGH) out of the tap, I would use <"

James' Planted Tank"> mix.

I probably would tweak it a little bit by leaving out the calcium sulphate (CaSO4.2H2O) and using potassium bicarbonate (KHCO3), rather than potassium carbonate (K2CO3)*. I would add more potassium bicarbonate (KHCO3) to give a bit more dKH. I'd approx. double the amount of calcium chloride (CaCl2.2H2O).

*I've just looked on a well known auction site and potassium carbonate is widely available and similarly priced to potassium bicarbonate, so you could use either.

The advantage of this is, mainly, that you can buy all the required chemical cheaply and easily as "food grade".

From the <"

linked web page">:

dKH:

**1dKH = 21.8 ppm HCO3-** and dGH

**= 1dGH = 7.143 ppm Ca++**
You can use the <"

Rotala Butterfly nutrient calculator"> to check your results.

I won't put in all the calculations, but you would use exactly the same procedure for the other compounds. You probably won't need this, but the process in "the calculation bit" allows you to work out the elements supplied for any compound. It is useful if you have a chemical not included in the <"

Rotala Butterfly database">.

**The calculation bit**
This is calculation for CaCl2.2H2O (so just supplying Ca++ and dGH).

You need to know the RAM of calcium (Ca) etc. I use a <"

web periodic table">, so that gives us all the RAM values: Ca = 40, Cl = 35.5, H= 1 & O = 16

We then need to add these values together to give us the RMM of CaCl.2H2O, so 40 + (35.5*2) + (1*4) + (16*2) = 40 + 71 + 4 + 32 =

**147**
and the percentage of calcium 40/147 ~ 27% Ca++.

Therefore if we add 10g of CaCl2.2H2O we've added 2.7g of calcium (Ca++)
I'm going to assume we have 100 litres of RO water and that 1dGH is 7 ppm of Ca (just to make the maths. a bit easier to follow).

Then we need to convert from <"

grams to ppm">. So 100 litres weighs 100 Kg, there are 1000g in 1 Kg and 100,000 g in 100 litres (easier in scientific notation (powers of 10) 10^2 x 100^3 = 10^5).

If we add 10g of CaCl2.2H2O (2.8g of calcium) to our 100 litres, we've added approx. 28 ppm Ca++. 28/7 = 4 and ~

**4 dGH.**

cheers Darrel