Hey David, how do you place your broms? Directly in the dirt or mounted to the wall or a log?
Some do fine is well draining soil but most need to "dry" as in the roots do not like to be soaked constantly. In my tank I have about 7 broms. Two are directly in the soil and do fine, others I have mounted to my logs. They will quickly grow air roots to get moisture from the air.
I also have no fan setup but I have a large tank, if you check my previous post below you will see where I placed my broms in the beginning...
The little green ones up front are doing great directly in soil/fluval. However the big red one in the back began to die and turn green (which is a sign of lack of light) I moved it to a hole in the top of one of the stumps and now it is doing great.
I guess in the end it is different for every tank/person/setup but I recommend going on etsy and finding one of the main brom sellers and ordering a pack of broms that you dont mind killing. I believe I have seen some with 10-15 pups for $50. Place them around your tank and just watch then, if they are growing new leaves out of the center then they are fine. If the leaves are curling then try moving them.
Apologies for the wall of text that does not really give you a concrete answer but hopefully it helps.