I have the same problem but I got out of it by folliar feeding with real light solution and using the same super light solution in the soil.

You should also invest in a commercial grade hydroponic fertilizer. You will need three (Grow, flower and micro) but you get to completely dial in what you need for each feed.

Also keep in mind that plants take in nutrients very quickly thru there leaves (Underside spraying is best) so if you keep flushing you can still give them the nutrients they need while the soil PH recovers.

I like the general hydroponics kit. It is for hydroponics but work great for soil too and will be better than these store bought brands some people use.