I think you made a mistake here. If you want to raise EC in the substrate you need to give EC higher than substrate to get desirable EC. Also increasing intervals between waterings can help even if you maintain the same EC. When substrate dries out EC is rising. But this can lead to salt build up, and can slow down the plant because it will struggle to find water while having issues with excessive osmotic pressure.
So if you have low EC in the substrate and you want to make it higher, increase EC of the solution at least till desirable EC, and water with 10-25% runoff.
If you have a high EC in the substrate and you want it lower, decrease EC of the solution so it is less than desirable EC. It will dissolve the excess of nutrients in few watering events. Another way is to feed every other watering.