I have a problem. I just bought 2 Ludwigia repens from the internet and they arrived Monday w/ other plants ordered. Today ,being Thursday, they have all but completely died . The stems are rotting from the bottom up except for one stem holding on for dear life. The Rotala Marcandra I ordered is doing the same thing except for 2 stems trying to make it. I have a 40 gallon w/ 130 watts 6,700k and 10,000k Sunpaq bulbs. My GH is 3*, KH is 3*, pH 6.8, Ammonia 0, Nitrite 0, Nitrate 0-10 ppm, CO2 about 22 ppm. I use the full line of Seachem Fert products and dose according to their dosing chart supplied on their site. I know that plants will shock when introduced, but the stems don't turn to 'mush'. :? Any ideas.