I have some huge lighter stumps, and was wondering if I could put these in my pond for structure. Not sure if the pine would mess with the water clarity.

If there is not a whole lot of dirt stuck to the remaining roots, you may have trouble getting them to sink. And it takes an amazing amount of added weights to get a large stump to stay down, even if it is a heavier wood. If you can stake & tie them down, it is a better method IMHO.

It's a shame to use them for structure instead of fire starting, but I bet they would last forever & make good structure if you can keep them down. I don't think the solidified sap will leach but it shouldn't hurt even if it does unless it's a really small pond.

I live in North Central Florida and there is Fat Lighter everywhere. I have enough to last me the rest of my life, plus some. I'm going to figure out to anchor them down some how. I believe they would make great cover. Some are as big as a truck bed.

I had to look up what the heck Fat Lighter was. I came up with this

http://www.survivalmonkey.com/Fat-lighter.htm

I have sunk stumps by drilling a hole in the side close to the bottom, inserting an eye bolt with wood screw thread, then using polybraid rope to attach a 1 gallon milk jug full of quickcrete that has an eyebolt imbedded in it. I just drop them overboard from the john boat where i want them.

Don't feel bad Ryan, my cousin lives around Macon, Ga and he told me about fat lighters a few years ago. He said he was going to bring me some up next time he came up. I told him I was glad because us Yankee's don't ever seem to be able to start a fire even with all the wood we have around here....he never laughs at my comments like that. I tried to explain to him that dry wood is as plentiful around here as hush puppies are down there, but he couldn't get past the fact that we don't use fat lighters up north. I changed the subject to avoid his blank stare yet again.