bogwood added to my aquarium has killed 10 baby guppies

Question
I added 2 pieces of bogwood to my aquarium last week, I thoroughly soaked it first.  The water in my aquarium turned brown which looked horrible during the day, but had a lovely effect in the evening.  However, I noticed some of my fish acting strangely.  firstly a mature female guppy died, then about 10 of my own (caught in the tank and reared in a baby tank) young guppies and platys died (they ranged between 8-12 weeks old) male & female, now one of my mature male guppies is swimming upside down.  The rest of the fish in the tank seem to be fine I have 4 neons, 3 plecs, 2 female guppies, 2 male guppies, 5 platys & 6 cardinal pencil type fish.  I had more young guppies & platys, but i have put them back into the baby tank just to be safe, can you advise me of the potential problem?

Answer
Hi,
I love the effects of bogwood for 2 major reasons. The first, the color makes the display look truly real. The second, the tannins it releases for weeks makes the water very soft and very acidic, perfect for stingrays.

Unfortunately, Guppies and other livebearers like to live in the opposite water chemistry, hard and alkaline. Not only did the water chemistry being off kill them, but they are also sensitive to the quick change.