I have had a few different stem plants that have basically melted in the last several months. I have gotten them in a couple of different places. My latest plant that I ordered was Scarlet Temple and Bocopa Caroliniana (both from Aquarium Co-op) and it has pretty much died. The stems have basically disintegrated after I planted them (and at least 2 other plants have done the same thing. I have other stem plants that are doing great!) So far the plants that have died are Ludwigia Ovalis, Hygrophila Blue, Bocopa and Scarlet Temple. I have Water Sprite that's doing awesome as well as Anacharis (which isn't growing great but is still growing). I dose Easy Green, Easy Iron and Seachem Potassium at least twice a week. I have Anubias, Java ferns, bucephalandra (at least 7 different types) subwassertang, Java and Christmas Moss, Cardinalis, crypts and rosette swords. All of these seem to be doing great!
I have 3 planted tanks and all 3 have the same substrate. I have fluval aqua soil topped with sand. And I put root tabs on the very bottom of the tank (in a Grid pattern before adding the soil). I just tested my water and all seems good with it. I have 0 Ammo, 0 Nitrite, 40 Nitrate, PH 7.6, GH 7, KH 4.5, Phosphate 200 and Alkalinity 80. I have attached a couple of pictures of what the stems are doing. I have Guppies, 2 types of Corydoras, Cherry Shrimp, a Nerite Snail, a Mystery Snail and some Ramshorn Snails.
Am I doing something wrong?