Yellow tank water

So, my axie tank water has this gross yellow-hue to it. I always siphon out poop (when I see it), food is always ravenously eaten, and I have a filter that's up to 55 gallons, where my tank is 40.

I put driftwood in there not too long ago, and I heard it could be tannins from the driftwood, but I also heard that with that comes a lower pH.
I tested my ammonia and pH:
Ammonia: 0
pH: 7.6
Soooo, that's not a low pH. I have a pH down solution I could toss in there, but I'm afraid that will mess with my ammonia level. I have REALLY hard water where I am, and getting ammonia to 0 is near impossible. I know it's not just me, the local plumber has an aquarium and he has the same issue, and he's tested the water supply with more than just an api kit.

Today is water-change day, I change around 25% every week or two, (two weeks this time because I was super sick recently)... They've gone this long without a water change before though, and never had this issue.

It doesn't seem to be affecting my axies, they're swimming around nicely, gills look nice, mooching for food as usual...

Any ideas would be appreciated!

It's most definitely the wood. I soaked mine for a week and a half before adding it to my tank and it still turns it yellow.

Agreed- my daughter has had a large piece in her 29 for a year now an it still tints the water! Lol-