Dry fertilizers causing water to turn yellow?
Hear me out.
For years I had low tech dirted tanks that I didn't fertilize and never had any issues with yellow water (I never used carbon or anything else that would remove discoloration).
3 years ago I started up my first high tech tank (also dirted) and began using the EI method to dose dry fertilizers that I got from aquariumfertilizers.com.
I began to notice that the tank was turning noticeably yellow within a week or so after water changes. If I went 2-3 weeks without a change it was quite dark yellow.
I figured it was just tannins leaching out of the dirt and that it would eventually go away. I ran this tank for 2 years and the yellowing never left. It was consistent as well, it never "lightened" over time as you would expect if the yellow causing stuff was coming from the dirt.
1 year ago, I "reset" this tank. I removed all the substrate, washed out all the dirt, and set it back up the same as it was before minus the dirt. Even a year later, the water turns yellow at the exact same rate that it did before.
My dry micro fertilizers are brown and if you take a small amount and mix with a small amount of water from the tap, the water turns significantly yellow. So, is this the culprit? Do all dry fertilizers do this?
I've never heard anyone discuss this before and was wondering if anyone had any thoughts regarding this.