I'm also a big proponent of bog filtration. After many years of trying different (inadequate) filters both homemade and store bought, I finally added a bog filter to my pond. The results were 100% amazing. I never had such clear water and with just about zero maintenance. No more rinsing of filter pads. And no UV lights. Just sit back, let the bog do its thing, and enjoy crystal clear water.
A bog is proportional to your pond. It can be big or small.
Plants are an essential part of your pond's ecology. Plant them directly in your pond or bog without pots if possible. The easier the roots have contact with the water the better.
Many of us use pure cat litter if a medium is needed. The cheap no frills type with no perfumes or other additives. Initially when using cat litter, the water will cloud a bit, but it will be clear the next day.
Also, you can add a top layer of small pebbles or stones to keep your cat litter or soil in place.
You will find from experience that ponding requires patience. Things dont happen immediately.
I can't stress enough how I love my bog. Instead of constant maintenance, I now can relax and enjoy it.