I use my Ninja but I use it several times a day for years. I make smoothies and shakes. So, it works perfectly for kava as well. I got mine at Walmart and remember it being very reasonably priced, even for smoothies and in place of a full on messy blender. Just my experience but it's a time saver for a daily kava drinker like me, who also drinks probiotic smoothies daily too!
I discovered, that by using a nutribullet, with either raw carrots or courgettes, about 180 grams, 25 grams organic wheat bran, which is an excellent prebiotic, plus essentially some raw sauerkraut, plus water of course....if left to sit in a glasd or jug in a warm place, it rapidly ferments like kefir. The blended wheat bran feeds the sauerkraut bacteria, it keeps rising up to the top, with a gap of air at the bottom of the vessel, you need to keep stirring it back in or it keeps rising out of the glass.
It goes all bubbly and fizzy like kefir, or Kombucha, like a super power probiotic, prebiotic concoction. Im sure with an array of amino acids and enzymes cteated as with kombucha for example.
It makes a really sharp, sour, refreshing tangy drink, with majorly enhanced probiotic levels as a result of the prebiotic wheat bran.