Looks like the main issues is nutrient deficency. As well as some Alage issues. This can mean several things in nutrient issues. Some questions about your set up to help qualify what to do. Anubias plants like you have are pretty easy slow growing lower light plants but they need good nutrients or they have issues as most plants do.
Is the light you list the pic of the only light source you have?
How often are you dosing your ferts?
Whats your light cycle in hours?
Any other light sources like windows?
How often do you add root tabs?
How often are your water changes? how large are they?
Have you read on and know what ferts are vital for your plants? Micro and macro?
Im not a big fan or fan at all of the pre bottled ferts as most of them are bottled fancy water with not enough or not all the right nutrients. Log ago before I switch to EI dosiing my ferts I tried many of these items. Now I dose nothing but dry ferts and I dose EI method that supplies non limiting ferts so you can eliminate nutrient deficency as a cause.
lets start with the API leaf zone. It primamrily is nothing more then Iron Potash/Potasium. It has traces of other things but in such small amounts its not effective.
Seachem flourish is nothing more then a Micro nutrent. It does not contain any macro's Again a watered down product that cost more.
Aqueon Plant food is also lacking many nutriens needed. If you check the nutrients listed, there is no nitrogen, or phosphorus listed and only a very little amount of potassium . It does contain a fair amount of micronutrients. Its very similar to the Flourish Micro your dosing.
Other issues with the above is the cost for whats needed. Switching to a full line of dry ferts will save you money, make it easier and last you longer plus get you want you need.
What you need is a full range of ferts to make sure your plants have everything they need.
This would be:
A micro nutrient source like Plantx CSM+B or Millers Microplex
A macro nutrient source like dosing indivudual sources of
Nitrogen
Phosphate
Potassium
Making sure to dose enough of all the above on a specific schedual that makes sure you have enough nutrients. This is the first place to start. Adding a liquid carbon source like Excel will not help nutrient issues like this. (its also not the same as Co2 either as its a different for of carbon.)
Where plants do badly alage thrives. So the goal is to get your plants to basically outcompete for nutrients and thrive.
