Presumed iron deficiency
Why are my plants showing a nutrient deficiency? As best I can tell, it is iron deficiency. It is most visible in the anubias, but the stem plants show it too, and my bamboo (which only has roots in water) shows it.
A farmer suggested to me that if it was his crops, he would lower the soil pH because iron gets tied up at high pH. My aquarium water is pH 8.2, but I don't know why. Well water pH is 7.6 to 7.8, but it rises to 8.2 in both of my aquariums.
29 gal aquarium with a low tech setup. Current Satellite + LED light on a split photoperiod (5 on, 4 off, 5 on). Mainly slow growing plants, and some riparium plants at the water surface. Tank is lightly stocked with 3 guppies, 1 harlequin rasbora, 1 betta, 2 BN pleco babies, 3 mystery snails, a bunch of red cherry shrimp and pest snails. Water changes are 30-40% every 2-3 weeks. Water changes are 1/3 RO water, 2/3 aged well water. Top off with RO water. I supplement with dry fertilizers (every other water change), potassium phosphate and a micro mix (Plantex CSM+B) with Mg, Cu, Fe, Mn, Mb, and Zn. I use EI dosing for low tech tanks for amounts. I don't supplement nitrogen because it's in the well water and current nitrogen readings in the tank are ~40. It's been a couple years since I sent the well water in for a lab analysis.