Be VERY careful with grapewood. As others said it does rot, which isn't really a problem for me as I use lots of outdoor sticks in my tanks. However the first and only time I tried grapewood it was a disaster. I am positive now that what I used had to of been treated with something. It is very important to soak the wood in a bucket for a couple days then test the water for ammonia and nitrite. My experiences with this type of wood, over a year ago, were not at all pleasant. Found the most awesome looking piece, it was big, over a foot long. I cleaned it up a bit at home and boiled it a lot. Then I did a full cleaning, rescaping, and planting of my 55 gallon. I added the wood and 24 hours later when I got home my tank had basically been nuked. Had a full blown bacterial bloom going, half my stock was dead, and only a quarter of my 30 fishes survived more then 3 months after this. What happened was the log produced high amounts of both ammonia and nitrite. It took me 3 days to suspect the log, during this time my tank was getting 100-200% water changes daily. As soon as I removed it the tank returned to normal within a few hours. I tested the log in a bin of water all by itself and 48 hours later it had about 2ppm ammonia and at least 3ppm of nitrite. Due to the cycle and plants in the tank the fish were all killed by extremely high nitrite. Except ember tetras because they are apparently the terminators of fish and can live for well over a year after enduring 4ppm nitrite, where as most will die within a couple months if they even survive exposure.