I'm looking for a new substrate that will help keep my ph closer to my tap water. I currently have a Biocube 14 set up with Turface MVP for substrate and am finding out that it may be dropping my ph. I live in the Charleston, SC area and we have soft water. Out of the tap the ph is around 6.8 with a KH of 1 and GH of 6 based on an API test kit. My tank ph is usually around 5.2 but jumps up to around 6.5 with a 50% water change then drops down again. Currently I have a Betta, 4 snails, and some some plants. I've seen some mixed reviews on store bought and alternative (Turface, blasting sand) substrates. Any recommendations? Thanks.