Gravel size for planted tanks
For those of us who want to grow low-light plants like anubias, java fern, and crypts in inert gravel (rhizomes above, of course), is there an optimum size range for the gravel? I've read a few recommendations for 2-4mm, which strikes me as correct. I ask because my gravel is 7-10mm, and I wonder if it's just a little too big for healthy rooting. In my first planted tank, I had a smaller gravel that was around 3-5mm, and root growth seemed much better. In my current gravel, root growth is much slower. I recently started using root tabs for the crypt, which has me thinking that my current gravel is probably allowing many of the nutrients to float up into the water column.
Is it worth replacing my current 7-10mm gravel with something in the 2-4mm size range? If nothing else, I assume the smaller gravel size will be better for keeping the root tabs' nutrients in the substrate. It's a 10-gallon tank, so we're not talking a huge amount of gravel to be changed.