Newly planted tank need some advice and help
I'd use a water conditioner during water change. Or leave water sitting out to breath for a day or 2 for the chlorine/chloramine to off gas. An air stone will help the process. Water from tap usually contains chlorine or chloramine which will kill your BB.
I had this problem when I first started my tank. Might be the elevated ammonia that caused the melt. I did about 70% to 80% water change everyday and the melt stopped after about a week. To salvage your melting plants, cut off the healthy parts, don't leave any melted parts on it. And clear off all melted parts from your tank including the roots. Float the healthy parts and they should grow some roots. Some will make it some will continue melting.
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