I have driftwood and pool sand in my Heckel layout...I use only RO, and add reject back for minerals...My water is adjusted to around 5.7 to fill, and bio load pulls that down to around 3.9TDS around 73..Salt will put your TDS thru the roof...I don't use any decholr's in this setup since it's all RO..I vac the sand every other day, and wc every other or 3rd day on occasion...120g tank...Not sure what's up...