It does sound like diatoms and normal in new set ups-how long has your tank been set up? Diatoms should wipe off easy so you can vacuum them out with one of your regular water changes.
Diatoms can also be caused by old light bulbs-how old are your bulbs and what is the kelvin rating on it.
Tannins in the water from either driftwood, use of IAL, oak leaf or the blackwater extract products can stain things brown and it is harder to get this off.
How many (10-right?) and what kind of plants do you have, I see you are using eco-complete for substrate...correct......
Adding 3-4 otos can help and they love diatoms, you already know that you still have to supplement feed them....good that you have done your research-so you may already know this too.....when you go to get them from the pet shop-find out how long they have been at the shop-you want them to have been at the shop for at least 2 weeks-this way you will know they are eating-look for nice round looking fish they are usually female get 2 of these and get 1 that looks healthy but slimmer that is the male....they seem happier when they have both sexes in the tank and with lots of plants you may even get eggs...never know.....
In a 10g-planted tank with 1 betta, 3-4 otos and some ghost shrimp with a 50% weekly water change...sounds good......
Love to see some pics.......