Tree Staking

Which PVC is best to use for staking tree tubes. Im probably going with 1/2 inch but didn't know if the white or gray was a better choice. The gray says sunlight resistant , but I can find nothing on the white PVC. Is one better than the other?
I have the gray up to 4 years old now and while I still buy them, in resetting some old ones I have had shards come off. wear safty goggles. a few have been broken off by deer running into them. They are more brittle than they were when new. I have them from two mfgs, JM Eagle and Cantex, but not sure if one is better than the other.
I've been using the white for all my 1.75 for a 10 ft piece. Works well and have had no issues.
I'm having issues with white PVC becoming very brittle after 2-3 years. When it shards off the pieces are very sharp. Cover the eyes. I'll be switching over to black on my next batch.