I am in the process of building some PVC crappie condos. They will be around 5' to 6' tall with branches about 30" long. Do yall think 20 lbs of concrete would be plenty to hold them in place or should I use more?
Also if I were to sink them in a river bend should I put them on the outside of the bend or inside?

Thank in advance.

It takes less weight than you might imagine. We sunk bundled brush and willow limb bundles with less than 20 lbs.
I would not think river placement would be a good idea if you want to fish over them long. All you have got to have is extra current (like a big rain) and you could kiss the condo good-bye.

Let me clarify I was refering to river bends in a lake (Sam Rayburn) not actual river. I would like some suggestions as to where to place them so I could fish them the majority of the year. Iwas thinking around 20-25' deep.

Your depth would work out just fine...just allow a little if your lake levels vary much during the year

20 pounds of weight should be more than enough for pvc.