GL, the reason UV's are not good with a bog filter is that you don't want to kill the stuff that goes through the pipe into the bog, as the plants need that stuff. A UV is good with slower water flow and going to a fountain or something like that.
I have to ask, because I don't think you said or I have forgotten, does your water flow into the bog through the bottom, up through the pea gravel, and then return to the pond? I'm assuming it does. That means that it's filtering your water and your new plants will begin to take off and when they do, you will notice the pond clearing quicker, too.
I had brown water this spring, sooo frustrated, went from crystal clear to murky brown. Not pea green like last year, brown. I too was frustrated, and then POOF, it cleared up! Almost overnight. Still wonder if it was the Pond Perfect, the quiilt batting I was cleaning out twice daily, the new old plants coming alive or the new plants taking off, or just patience and ALL of these items. Take pics looking down into your pond daily and maybe that will help you see the difference.
BTW, I and most on here do not vacuum their ponds. They use a fine mesh net and net the bottom. Some stuff on the bottom is ok to have, as it harbors beneficial bacteria. I learned that when thinking I needed to net all the gunk when I had brown water, and someone said to leave it, unless I had lots of leaves, and I have no leaves.
I also wonder if your shark or fish were spawning, stirring up your muck on the bottom, and if that caused the problem in the beginning and then things escalated from there, with the water changes, etc. BTW, what looks awful to us, like you don't want to put your hands in it, may be heaven to the fish! They don't ask for crystal clear water, that's for the benefit of us humans.

They say best water to start out fry is pea green water. But, I'm like you, I want to see all my fish!

I think you're making progress, I'm really glad for you.
