Sounds like your water is fine, although the other two basic parameters are pH and temp. Greenish-brown water is strange. Do you have a source of tannins in your tank, like new driftwood? Can it be due to microscopic green algae, as in "the tank gets too much sun light and not enough water changes"? Certainly carbon filter will get rid of the color (if it is not algae) but it is much better to understand the source of the color in the first place.
The sand is sand everywhere. I'd just make sure it has no artificial additives (100% sand) and I'd wash it a few times before adding to the tank. Add a little, like 1/5th, first and wait for a few days, a week, to see what happens. If fish exhibit no behavioral changes, add 1/3-1/2 - observe - add all.
This fish grows big fast. Normally they far exceed 1 foot in the first year (contrary to the post above in which, if I had to guess, the fish is strongly stunted - a practice that has no supporters among high level hobbyists, experts, ichthyologists). They will hit 2' in 2 years for sure in normal circumstances. It will take another 5-10 years for them to reach their full adult length of about 3' TL.
Keeping your better half happy is admirable. I share the taste in cats with her/him.
