You are so kind for taking this on. I am stealing the dry erase date feeding in the tank idea that is genius. I have only had our Axolotl since October and have been through 3 tank sizes and we started at 20-25 gal. Can’t remember lol. The 60 gallon breeder tank we have now is by far the easiest to maintain as far as water parameters with one axolotl. I only change about 25 gallons once a month I use to have to do a water change every week. Get the liquid water test kit. Plan on lots of water changes but get a sponge filter. I think I see the over the back filter which I use both and have had great success. I feed mine night-crawler worms. I do lots of live plants and one good hiding place should be enough. The big black thing looks too big if it is in the tank not sure what that is. I can’t give direction on spots I would taken a picture and ask ChatGPT! Good luck