I always get green algea when I add plant fertilizer...
even 1/10th the amount does it.

Hagen, Seachem, RedSea....
Some with iron, some without.

Whats worse was I knew this, added Hagen to my tank a month ago...
and my 14" tall anubias nana with 12 leaves all got infested with
green diatoms, so I had to remove all but 2 leaves.

If you are going to fertilize, I recommend you use the substrate
fertilizer tablets.