I got some once. I used them as a source of natural carbon to clear up a tank that was a bit cloudy (not an algae outbreak).
It was a nice natural way of clearing things up.
I just removed once they weren't doing any more good. They aren't living, so no need to keep them in there. And I just used it like a carbon source, so once all of the carbon has bonded with whatever chemicals, it's useless. So I just removed it at that point.
Sorry man, can't help you with that.
You might want to look into a planted aquarium where the plants are actually alive if you like that idea. Then, you don't have to replace them since they are living. Live plants will help water quality as well.
I would use lillys instead of almond leaves for decorations but almond leaves are really good![]()
Don't know how long they last but I've seen people even put leaves from their yard in their tank(not the best idea) At any rate I think you should be good for a year and with ample water circulation and some burrowing fish (to keep things from sitting and rotting so much) you can probably get longer out of them. You should see or smell rot before it gets to far along. I imagine berried leaves will rot faster than those sitting loose on the tank bottom.