I recently set up an Altum biotope with some UniPac Okishii artificial rock and driftwood. After the initial tank fill the water was a nice amber colour from the tannins leeching from the driftwood. After a few weeks with water changes the tannins are now reducing. Has anyone found any definite benefits to using a blackwater extract ? I have a small - 250ml - bottle of JBL Tropol which I used on my last water change but it's fairly expensive at this size. I could buy a 5L jug which is considerably cheaper per ml but I have to import it directly from Germany as the UK distrubutor does not hold any stocks in this size. Or is it just an aesthetic thing ?