techniflora seaweed extract. goes far as it is very concentrated and is like 16$. use some high brix molasses with it and it'll kill the game. idk what kinda medium youre using, if its Rockwool cubes and slabs maybe use the molasses sparingly (especially if using slabs). the molasses will foam in the res. its ok. no problem, don't worry. you will have to run a sponge or cloth along your res when you clean every change. should anyways. but its cheap. there are TONS of good seaweed sups, but this one is cheap and effective. I like to enzymatically digest kelp meal in a 5 gal bucket and use it as a feed for my compost tea, which I put in my res heavily. but I use coco chips and diatomaceous rock in containers.