. I am having the same problem on my 10gal shrimp tank, H2O goes to 6.0 after 24 hrs. I took all my wood out and have been doing H2O changes, Added some lime stone. Made sure there was no dead plants and nothing rotten. Also added baking soda. Trying to get it to get above 7. And in my other tanks I would love this softer H2O. I will let you know if mine corrects with what I am doing.