I have grapevine in my tank and there should be no hurry in getting it in there. I have large pieces in my 125g the take up half the tank, and they took about a week to get to the point I would add them they could have gone longer and I would recommend longer soaking in you have the time and space. I soaked them using the hottest water out of the tap in the bathtub. You'll have to put bricks on the branch to hold it under the water. The first day I changed out the water 4 times, it looked like iced tea the first time it was so dark! Over the next week I changed it out as much as I could. By the end of the week I couldn't bear using more hot water, I was scared of the water/heating bill by that point, figuring I used probably 500+ gallons soaking the wood. At this point I just moved it to the tank and weighted it down because it would still float a little. The tank turned yellow-brown after about 3-4 days, I did a 50% water change. I kept on doing higher percentage water changes since, about 30% twice a week for a month now. At least I feel using water in this respect isn't wasting it. The fish don't mind a yellow tint either. Now the other 'issue' I found with grapevine is that it leaches sugars in the beginning too. Usually after a few days of soaking you'll see a whitish or clear ooze on the branch in spots - baby plecos love this stuff. I dropped in a L083 (gibby) and he ate the sugars off and gained 2 inches in just over a month and kept the branches clean as well as munched the soft brown algae in the tank and cleaned scraps up. I have heard the ooze will dissolve if left alone too.
Fast forward to one month in the tank. At this point the wood is water logged and no longer needed weights to keep it in place, it stays at the bottom of the tank. No more ooze, the pleco still is happily chewing on it and keeps it so clean I can't tell if algae even grows on it. The tall parts are at the surface of the water right under the light which is on 10 hours but he goes to town on it every night. Part of the plan was to get algae to grow on it for him, he may just eat it off every night. Still leeches, not too bad, water changes keep it looking almost normal but you can see the yellow tint looking thru the tank from the side and if you go down to one water change a week you'll notice the yellow tint on day 5.
I'm now at the 2 month mark. It still will get a yellow tint at the 5 day mark, so twice a week water changes are best but I can go with two 25% changes instead of 30%. Still no algae, pleco very active on it though. The wood does get softer and eventually will break up I think - but I would estimate now that it would take 2 years to do it, maybe more. When moving the wood now, if you rub the surface, you'll get a brown wood flecks coming off. It doesn't do it in the tank on it's own though, and I assume the pleco is feasting on it at well. Not a bad investment for decor, but long term I think manzanita wood or hardwood would be better.
