What kind of bug is this?

I have an on going problem with these little blak bugs and can't figure out how to get rid of them. I have taken them into a few of my local hydroponic stores and they say they have never seen them before. They are black with six legs, no wings and are living in the resevoir, on the roots and in the soil!! Help, I have tried using AzaMax and other general mite control products to no avail

Hard to tell for sure but looks like a root aphid.




J