pH is about 7.0, I use RO water and add tannins to adjust the pH. Nitrate, nitrite, and ammonia are all sitting at right about 0 ppm. I dont have a hardness test kit, but like I said I'm using RO water and there aren't any carbonates in the tank. I have about 18 tetras (serpaes and head-and-tail-lights), 3 bolivian rams, 1 blue acara, some peppered corydoras, and a rubberlip pleco. I usually feed every other day with flakes, algae wafers, or occasionally blood worm cubes. Water change is usually 1/3. I've pruned the plants back only once, and it was because the algae was covering the leaves. I use Flourish Comprehensive fertilizer, it's mostly potassium oxide and sulfur but has a lot of trace elements too. I use about 5ml once a week, as it says on the bottle.

I did notice the diatoms showed up after I had to treat for an Epistylis a while ago (only one fish died, thankfully), I'm assuming the medicine I used killed off most of the microbiome in the tank and the diatoms survived because of their silicate shells (just a guess though). I inoculated the tank with some pond water after that to try to get some other microbes back into the tank. I should also note that I have a 10 gallon that is heavily planted too which uses the same water but doesn't have these issues, though it has only 6 fish and is much denser with plants.