Another common contaminant is Ectocarpus, which is a filamentous brown algae. Ectocarpus spp. have a very quick lifecycle, so given the opportunity, they can easily grow and compete with the kelp developing on your spools.

Under the microscope, Ectocarpus will look like a branch-like structure that continues to grow out into long, feathery strands attached to the spools. 

If you begin to notice Ectocarpus under the microscope, leave your spools exposed to air for 10-15 minutes during your weekly water changes, as Ectocarpus doesn’t tolerate desiccation well¹. If possible, it is best to wait to air dry your spools until the kelp has reached the microscopic sporophyte phase, so you can be sure that the seed is hardy enough to withstand the prolonged air exposure. Reducing the light intensity within your tanks can also help eliminate Ectocarpus spp. contamination². The trade-off of lowering the light level can be slower kelp growth.