Ants, not shure if they will hurt your plants. Maybe throw a few shrimp on the barby to keep them happy. LOL No really sorry about that. You might ask in the hydro section. My brother had that problem in his house but was using soil. I have a small hydro in my shed and you can't turn around in my yard without stepping on ants of all kinds. I have had no bug prob's and they can get in there if they want. I had a few algea nats but no soil for them to live in,They die in the heat of the light. What kind are they ? Small blackones or fireants.