How long does grape vine last

Hi guys,
So, I was just wondering....(which is always dangerous). I have bought some very beautiful grape vine pieces - quite thick ones, and they are busy soaking in my fish pond getting ready to put into my tank. Does anyone know if it lasts underwater for as reasonable amount of time - a year or 18 months at least I HOPE!! I guess the slightly thinner pieces will decay first, which is ok, I just don,t wanna put them in and then 6 months later have to chuck them out because they rot too fast.
And also - does it leach out the tannins quickly.

 

The grapevine in my tank lasted almost 2 years. Unfortunately it leaches tannins for a long time. You will also take forever to clean it. It has a double layer of bark. The top layer peels of easily. The second layer took me longer.

 

I had mine for a almost a year in my tank. The thinner pieces eventually get pap and start dissolving. The thicker piece seemed fine enough for me to sell it to someone else.

 

Use a high pressure machine to blast off all the extra's.