This little DIY hack won't cure diatoms but I've found it helpful in removing them from the leaves of my Anubias.
Grab an old t-short the rougher the fabric the better.
Cut up a section shirt.
Drape it over the tip of your thumb.
Wrap a rubber band around the knuckle of your thumb.
Rub leaf with pointer finger and thumb.
It's worked rather well for me when using just plain fingers wasn't getting all of the diatoms off. It doesn't work so well on smaller leaf plants like my S. Repens.