Just completed a pond install on our property, appx. 1.5 to 2 acres in size and average depth of 8-9 ft. I have placed some fish habitat such as Concrete and Cinder Blocks. I have a large brush pile that has been burnt over the last couple years and there are 3 or 4, 8-12 foot long trees (no branches just trunk and root ball) that are black from being burnt. I have read some of these threads and are worried of these being toxic to fish because of the possibility of tannins? Any help is greatly appreciated.