Plots of Arabidopsis thaliana L. plants were grown in two hydroponic systems, one using a solid rooting support media and the other a flowing solution culture. Both were tested with various concentrations of bromacil, dichlobenil, copper sulfate and 3-aminotriazole. The effects on biomass production were compared. Plants treated with bromacil at concentrations up to 0.05 mg/1 were similarly reduced in growth in both culture methods. However, the toxic effects of dichlobenil, copper sulfate and 3-aminotriazole were different for both culture methods. Solution culture testing was generally more sensitive and since roots were bathed directly in a solution of known pH, nutrient level and chemical concentration, the test conditions were more accurately defined.