well if your tap water is a high ph level use that or try 1/2 tsp sodium bicarbonate (baking soda)
theres no buffer in ro water so a tiny bit of acid sends it all over the shop so you could add 75% ro water and 25% tap to add background ec
theres no buffer in ro water so a tiny bit of acid sends it all over the shop so you could add 75% ro water and 25% tap to add background ec