About your question on keeping them: pH 6.6-6.8 would be best, also temps between 23C - 25C would also show their best colors. Make sure your GH and KH aren't too high. If you feed meaty foods, such as most prepared shrimp pellets, they will grow faster. Feeding more vegetable based foods (veggie sticks, boiled spinach) will enhance coloration. Whenever I do water changes and top offs, I add a tiny amount of Shirakura White Powder - it's a calcium additive that will help the shrimp molt. Genetics also play a key role in coloration; usually higher grades will have more solid white and red. I didn't have much success in keeping and breeding CRS until I switched over to ADA Amazonia substrate. Hope this helps!