Hi John!
Sorry to hear that u are having some issue with your beardie's not growing. So u have 2 of them & neither of them are growing? If u could please answer a few questions, it could help identify what the issue may be.
What is the basking spot temps?
When u say u are using 40 gallon tank for their enclosures...do u mean a 40 gallon breeder or a regular 40 gallon tank?
UVB lighting - U said u provide the 10.0 light. Can u please tell us if that is a long tube or coil? What is the make & brand? The best recomended UVB lights are the ReptiSun 10 or the ReptiGlo 8 long tube lighting that should stretch across the top of the tank.
If I read your post correctly, U said that the humidity depends on when u mist? Are u misting the enclosure? Bearded Dragons come from a very dry climate & do not need humidity in their cage. In fact, too much humidity can cause respitory & health issues. I mist Drago a few times a week as well but I do it outside of his enclosure. I do provide a water dish, however I have never seen him actually use it! lol
How long has it been since they seemed to have stopped growing or have thay always seemed to stay pretty small?
Romaine lettuce is not very nutritional for your beardie's. They should be offered a daily salad which should consist of any of the following...mustard greens, turnip greens, dandelion greens, turnip greens, butternut squash &/or acorn squash. There are many others as well. Beautiful Dragons.com has a great nutrition chart which I love because it will explain why certain foods are bad &/or not nutritious.
Sorry to ask so many questions...just trying to help :wink:
~Sandy