There are products that you can buy that add all the trace elements into the water however on a regular basis these products can be expensive. Here is a cheaper alternative than buying shop products, it was provided by MCH and I have been using it for a long time now.
"Common bicarbonate of soda is effective at raising the PH, not to mention it is very inexpensive. Epsom salts (i.e magnesium sulfate) can be used to harden the water in lieu of calcium. Then you could also add aquarium salt (i.e non-iodized salt) to provide trace elements and potassium. For every 5 gallons of water add 1 tablespoon of epsom salts, 1 teaspoon of baking powder soda and 1 teaspoon of aquarium salt".