High PitteJasKorels,
You need to flush your soil. The reason for this rising pH is actually really positive and normal for a healthy grow on soil. Your plants are eating the nutritiens really fast. As the plants absorb these nutrients through their root systems, the system slowly loses its acidity to become alkaline.
You can do this flushing by slowly pour water pH 6 onto the top of the soil, allowing it to drain freely from the bottom of the pot. Pour slowly, so the water doesn't overflow from the top of the pot. Use approximately four times the pot's volume in water to flush the soil. For example, use 1 gallon of water for a 1 quart pot.
After the flushing you need to let the soil (almost) dry out completely. And start watering with a max EC of 1.8 (do not give more because this will cause nutrients lockout). And keep the pH lower. The best would be around 6 then the pH from your soil will be slightly higher.
Happy Growing! 😋