Adding top layer of sand - some concerns...
I have been battling pests for the first time during this grow, I believe they are fungus gnats. I have been using neem oil with no improvement. When the plants were younger I put a 1/2" layer of sand on the top of the soil on each plant and the bugs were gone within 48 hours. I was experiencing some issues with yellowing at the time, and I wanted to see what your experiences were when adding sand to your soil. The sand is not from the beach, from a local hardware store.
A few questions regaurding the use of sand:
1) What does sand do to the PH of my soil? Since the sand is on the top, the water and nutrients I give them go through the sand first. How does the top layer of sand affect the PH?
2) Should I do anything to the sand before using? It's coming from a huge pile outside the hardware store.
Any other issues or concerns I should be aware of?
Thanks very much,