I have an 8m old tank, 75 gallon, well stocked. I am using inert substrate. I always plant with root tabs. Crypyts are doing well. Pretty much everything else eventually melts and it melts from the bottom up. If I float things they do great, put on roots, but once it goes in the sandbed it dies. Sometimes it take 4 weeks to happen. What's weird is the stuff grows so it's not like it's not getting some nutrients.
Plants doing poorly are water wisteria, bacopa, val, dwarf sarg, and ludwigia. Any advice on what I'm doing wrong? I'm considering mounting the stuff doing well to rocks or wood and not planting it to see how it'll do but it'll be impossible to get any plant density that way. Substrate is not compressed. Plenty of fish poop mixed in it by now too. I suction it but not aggressively about once a month.