Aquariums: 40 Gallon Breeder — Minor Haze That Won’t Go Away

Hey everyone! I’m looking for some advice on getting my 40 gallon breeder crystal clear.
The tank has been cycled for about 2 months, and my parameters are:
Ammonia: 0
Nitrite: 0
Nitrate: 10
Temperature: 75°F
pH: 7.6
GH: 9
KH: 7
TDS: 280-320
Those are basically my local tap-water parameters.
I’m using an inert substrate that was thoroughly cleaned, along with Seiryu stone and one large piece of Mopani wood. Both the stone and wood were cleaned before being added.
I originally wondered if the Seiryu was causing the haze, so I tested the tank without it. The water looked essentially the same even after water changes. I also tried removing the wood, with the same result.
The tank has a minor haze. It isn’t severely cloudy, but I can see the difference compared to truly crystal-clear water, especially when looking through the tank.
For filtration, I’m running a Fluval 307 and have experimented with progressively finer mechanical filtration, currently going down to 10-micron filter floss. I’ve also tried Seachem Clarity, which may have helped a little, but nothing significant.
I also have an inline Fluval FX UV that is connected and working.
I have a bunch of plants coming soon, but I’m mainly trying to figure out what could be causing this persistent minor haze and what I can do to get that crystal-clear look.
At this point I’m tempted to just accept it, but my OCD is telling me otherwise 😂
Any ideas or suggestions would be greatly appreciated. Thanks!