can i use a different type of medium to up pot

You can absolutely change the medium when you repot your plants. While it's generally recommended to maintain consistency for the sake of the plant's stability and to avoid shocking it with sudden changes, transitioning to a different medium can be done with care. Here are some steps to consider: Gradual Transition: If you're switching to a different type of medium, such as from promix HP with perlite to FoxFarm Ocean Forest (FFOF), it's best to transition gradually. You can do this by mixing the new medium with the old one over a few repottings. This helps the plant acclimate to the new conditions without experiencing sudden shock. Adjusting Watering: Different mediums have different water retention properties. FFOF tends to hold more moisture compared to promix HP with perlite. Be mindful of this difference and adjust your watering schedule accordingly to prevent overwatering or underwatering. Monitoring Plant Health: Keep an eye on your plants after repotting to ensure they are adjusting well to the new medium. Look for signs of stress such as wilting or yellowing leaves and adjust care as needed. Nutrient Consideration: If you're switching to a medium like FFOF, which often contains added nutrients, you may need to adjust your fertilization regimen. Monitor the plant's nutrient needs and supplement accordingly. By taking these steps and being attentive to your plants' needs, you can successfully transition to a different medium for repotting. Have a nice grow !

If you can guarantee the same aeration and water capacity properties per volume, it would be fine. The risk is that some portion dries faster or remains wetter longer etc... you'll have areas of rootzone that might dry up inside the pot where you cannot observe the problem occuring until something bad happens above ground. As long as the characteristics ar enot too drastically different, i'm sure it's fine. If you can avoid it, keep it simple and avoid it.