Hi
@npaulson,
This is a good example that sometimes things are not as they appear. With the water parameter information I think I have an idea of the problem. I downloaded your picture, cropped, enhanced, and sharpened it, and this is what I saw:
The leaf at the top arrow shows interveinal chlorosis (darker leaf veins with lighter areas between). The other two arrows are pointing at new leaves that are emerging showing almost complete chlorosis (yellowing). When this occurs on newer leaves the likely issue is related to iron availability or uptake. I don't think the problem is availability per se, I think it is related to an inability of the plants to use the iron in the Easy Green.
Why do I say that? I cannot find where Easy Green lists the actual ingredients, specifically the type of iron used in their fertilizer, however it is likely to be ETDA Chelated Iron. Why is that the most likely? Because it is the least expensive form of iron for fertilizer and is the most often used (including in CSM+B). ETDA chelated iron works fine in acidic conditions making 100% of the iron in solution available to the plants at a pH of 6.2 or lower. However, as the pH increases the availability of ETDA chelated iron decreases, at a pH of 7.0 only 20% of the iron in solution is available to the plants. At a pH of 7.8 to 8.0 about the amount 2% - 3% of the of iron in solution is available to the plants. Here is a chart showing some of the common forms of iron used as plant fertilizer and the solubility (availability) to plants at various pH levels.
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So what do we do? Adjusting your pH downward may or may not be an option. Even if you did when you do your weekly 50% water changes chances are the pH of the water out of the tap will increase the pH to an elevated level. If it was my tank I would pick up a bottle of Seachem Flourish Iron. It if made from ferrous iron gluconate and is relatively easy for plants to absorb even in higher pH tanks. Follow the suggesting dosing on the bottle twice a week, each dosing will add 0.26 ppm of iron to your tank.
Dose the Seachem Flourish Iron on days you do not dose the Easy Green. Now watch the
new leaves as they emerge and mature. DO NOT WATCH ANY EXISTING LEAVES, they will not improve and may continue to decline and die. Do this for four (4) weeks and let us know how the new leaves are looking. They should be greener, healthier, and you may see an increase in the growth rate. Progress reports with pictures are always appreciated. Hope this helps! -Roy
