What can I do to make my slip hold more crappie ? Should I build some pvc condos or bamboo or just use x-mas trees? I have all just wanting to know what works best. Should I put a white light or green under water light? Someone help me out here how deep should I put it all? Thanks for any advice.

Any of the things you mentioned will help. I prefer willow, bamboo, Christmas trees and PVC, in that order. However, something is better than nothing, use what you have available. Lights should help for night fishing. I like to hang the brush so it can be adjusted if need be. I try to use just enough weight to sink the brush, otherwise adjstments can be challenging.
Everyone has their own way, this is just how I like to do it.

I think the single best thing you can do to hold crappie on structure is to darken the water as much as possible. hang tarps down the sides of the slip or better yet under the walkways. hang one off the back of the slip. AND tie one so it covers the top od the water and cut some holes in it where your structure is. leave about 6 inches of room between the tarp and the walkways and you cnn fish the entire perimeter. The water will almost look black and da fish like it. With structure in there they will stay!

Black crappie really like darker water.

I like to use PVC as you don't get hung up. take sandpaper and rough up and paint with black paint. Algae will grow on this quick.

My slip sets in about 25 foot right now, I sunk 16-20 feet tall bamboo in concrete buckets down to about 20-22 feet, this was about a month ago, fished it twice and have not had a bite, I am going to put some range cubes out in pvc pipes with slits cut in it to attract minnows, I am thinking that after the spawn when the crappie move back out they will find my honey hole, at least I hope so.

I will assure you that instead of drawing in crappie, range cubes will bring every carp in the area to your slip. About 15 years ago, I thought much like what you're saying. It did nothing for the crappie but I had a ball catching carp on crappie tackle (and yes a carp will eat a crappie jig).

Range Cubes will surely put Carp in your slip.

I agree with BigDave crappie are attracted to boathouses for the shade. The structure such as trees, pvc, or bamboo is also a necessity. In our boathouse, the slips with big pontoon boats or boats that take up the majority of the slip are the slips that produce best. Not saying you can't catch fish out of an open slip, I've done it thousands of times. Just sayin, shade+structure=your best bet. In my opinion I love slips that are LOADED up with brush and I prefer natural instead of bamboo.

Big Dave hit the nail on the head. The darker the better and we use PVC. You will get hung up on the trees. I do have some bamboo trees hanging in the corners.

Well I really do not want to draw a bunch of carp to my slip, maybe I will hang a tarp on the open end of my slip to make it darker in there, really hate to do that as well because we have a really nice view.

This is what i built today

I totally agree with BigDave1. Also, if you can position/suspend the trees under the deck surfaces - it works better; less hangups.

Which lake? GV is very difficult since the water is soooooo low at the slips. Good luck!