I think that even a 1/2 tank change is not going to be enough, 10g of fishes peeing is equivalent to less than a tbsp of our pee, and it is daily not a single dump. if it was me (from my many years of running planted tanks and mini-aquaponics) I would drain it all out, and then start over with fresh water, use a pinch of fish food(no fish) a day along with adding fresh bacteria starter for 1-2 weeks and your tank will be ready to go. Don't even bother testing the tank for the first several days as there will be fun swings. Once you add fish, remember not to add all at once as each increased load will result in a wobble while the bacteria adjust. 2-3 fish per week until you get your max load, normally 1" total fish / gallon but with plants it is higher so you will have to play with that. I also suggest you get aquarium safe plant fertilzer such as seachem flourish to add back in the calcium, iron, and potassium that the plants will suck up. Your fish will really only be feeding the plants nitrogen, so an imbalance does happen after a few months. with the small setups, you also quickly run into the water getting hard as certain salts are not picked up by the plants, while much water does evaporate. Make regular water changes and get a test kit for hardness. Constantly adding acids or bases to try to balance the tank will result in much fish death. Also with most of my planted setups, I never had the nitrite spike, and the nitrates were actually lower in the tank than out of the faucet due to the action of the plants (they prefere ammonia to nitrates) so don't worry if you don't see the nitrite spike, as long as ammonia goes down to 0.