Tried Agave, works wonders on buds - make sure to use good nutrients together.
I use Agave during all flowering and after every flush (2-3 times during flowering, I use the Molasses (Blackrabbit - something like that - that contains also important minerals).
This is because after the flush, I leave the plant without water (since it's not so hot outside, there's less need for watering) so that the roots "breath".
This first meal after flushing is important, most of the nutrients are absorbed quite quickly.
After that, all other waterings will be with Agave, another precious Mexican treasure...

The Agave is specially beneficial if you flush your plants at the end. During the week (or 2 if you're growing in a massive pot) you only pour water, add some Agave to it. It's pure carb, without the minerals that you're trying to remove, and will energize and sweeten your sticky mellow buds.
Around 2 ml/L should do the trick.
Cheers!
Mr. Sky