Cholla Wood is actually the skeleton from a desert cactus! Shrimp love Cholla wood, and you will actually see it shrinking over time as they work on eating the bacterial layer that is eating the "wood". Cholla wood does float and leach a ton of tannins, that is why we offer a pre-sunk version. It takes us about 7-10 days to sink the Cholla wood in a bucket, doing twice a day water changes. Our pre-sunk Cholla wood will most likely continue to leach some tannins into your water, but it is significantly less than you would expect from a new piece.
NOTE: Shrimp are NOT included with the Cholla wood, it is to show how much shrimp really love this stuff. Also, due to natural variance in the way each piece of Cholla is grown, yours will not look exactly like the one in the picture.