I have had to sign up to comment, I read this thread before and that's when j realised mine were dying as they turnt a bright red. Water was fine, lots of filtration, everything was great so I asked the pet shop with a guy who knows a great deal. He asked me do I dispose of the sponge that the plants come in or the white pots, which I don't and he said you need too when keeping shrimp and snails as these pots and sponge have pesticide added to them so in transit no pest snails can latch on. He suggested that I take all the sponge out and gently peel it off the roots, scoop out any left over which I have done then leave it for four weeks which I have done although he did warn me because I have had it in my tank a while it may be too late. I have now got some new shrimp and all seems ok so we will see how it goes. Hope this helps someone else