Soft water means low ion concentration, usually calcium/magnesium. Hard water means high ion concentration, usually calcium/magnesium.
There's no way to say what is the best for you when growing in soil without a soil quality test.
Anyway, here's a breakdown of Jack's Hydroponic 5-12-16
First off, let me move back to metric units. 13 oz/100gal ~ 1g/L
So, 1 g/L of 5-12-26 Hydroponic will provide you with the following nutrient concentrations in distilled water:
Total Nitrogen - 50 ppm
Phosphorus - 52 ppm (Phosphate as P2O5 - 120 ppm)
Potassium - 216 ppm (Soluble Potash as K2O - 260ppm)
Calcium - 0 ppm
Magnesium - 63 ppm
Sulfur - 82 ppm
Boron - 0.5 ppm
Iron - 3 ppm
Manganese - 0.5 ppm
Zinc - 0.2 ppm
Copper - 0.2 ppm
Molybdenum - 0.1 ppm
Now, for the calcium nitrate. Calcium nitrate fertilizers are a 15.5-0-0 + 19%Ca.
1.5 g/L:
Total Nitrogen - 232 ppm
Calcium - 285 ppm
1 g/L:
Total Nitrogen - 155 ppm
Calcium - 190 ppm
0.75 g/L:
Total Nitrogen - 116 ppm
Calcium - 142 ppm
0.5 g/L:
Total Nitrogen - 77 ppm
Calcium - 95 ppm
Alright. Now we know what both can provide us. But, that doesn't really tell us what we should really be using.
So, lets just get a starting point. I chose 1 g/L for a reason.
At 1 g/L of both 5-12-26 Hydroponic and calcium nitrate, we get a complete blend that has the following concentrations:
Total Nitrogen - 205 ppm
Phosphorus - 52 ppm (Phosphate as P2O5 - 120 ppm)
Potassium - 216 ppm (Soluble Potash as K2O - 260ppm)
Calcium - 190 ppm
Magnesium - 63 ppm
Sulfur - 82 ppm
Boron - 0.5 ppm
Iron - 3 ppm
Manganese - 0.5 ppm
Zinc - 0.2 ppm
Copper - 0.2 ppm
Molybdenum - 0.1 ppm
This ends up being a really good and balanced veg stage fertilizer blend. It's not too concentrated and is not going to stress the plants that much. You will see good strong growth.
Now, if you want to increase the concentration of Nitrogen from here, often times, you may be told to use more calcium nitrate. Like increasing calcium nitrate to 1.5 g/L with your 1 g/L of 5-12-26 Hydroponic.
This would have the following effect on the blend I just showed:
Total Nitrogen - 282 ppm
Calcium - 285 ppm
Personally, I find 285 ppm calcium to be too high. So, instead of adding more calcium nitrate, I would add some Urea. Urea is a 46-0-0 fertilizer. I would add 0.15 g/L of urea. 0.15 g/L of urea will add 69 ppm of nitrogen to your fertilizer blend.
Total Nitrogen is now 274 ppm
But, ya know, good flowering/bloom fertilizer blends are lower in nitrogen in relation to everything else. So, lets see how we would create that.
First, I'm going to add 0.75 g/L of both 5-12-26 Hydroponic and calcium nitrate. Got to keep that nitrogen down.
Total Nitrogen - 154 ppm
Phosphorus - 39 ppm (Phosphate as P2O5 - 90 ppm)
Potassium - 162 ppm (Soluble Potash as K2O - 195 ppm)
Calcium - 143 ppm
Magnesium - 47 ppm
Sulfur - 62 ppm
Boron - 0.38 ppm
Iron - 2.25 ppm
Manganese - 0.38 ppm
Zinc - 0.15 ppm
Copper - 0.15 ppm
Molybdenum - 0.08 ppm
Alright, so this changed a lot. But, the important thing is, we dropped our nitrogen down by a lot. Don't worry about the micronutrients, you'll be fine with a small drop like that. What you do want to pay attention to though, is potassium. We need to get that potassium back up to where it was, maybe a little higher even.
We're going to use Potassium Sulfate for this. Potassium Sulfate is a 0-0-52 +18%S.
Lets add 0.25 g/L of Potassium Sulfate. This adds the following:
Potassium - 108 ppm (Soluble Potash as K2O - 130 ppm)
Sulfur - 45 ppm
This changes the completed feeding solution to the following:
Total Nitrogen - 154 ppm
Phosphorus - 39 ppm (Phosphate as P2O5 - 90 ppm)
Potassium - 270 ppm (Soluble Potash as K2O - 325 ppm)
Calcium - 143 ppm
Magnesium - 47 ppm
Sulfur - 107 ppm
Boron - 0.38 ppm
Iron - 2.25 ppm
Manganese - 0.38 ppm
Zinc - 0.15 ppm
Copper - 0.15 ppm
Molybdenum - 0.08 ppm
To reduce your nitrogen concentration even further, you'll have to use even less calcium nitrate. So, dropping calcium nitrate to 0.5 g/L will reduce your nitrogen by 39 ppm, down to 115 ppm. Remember though, that this also drops calcium concentration by 47 ppm. You aren't that likely to have a calcium deficiency at this point, but if you do, just add back some of that calcium nitrate.