This is the traditional recipe. To avoid confusion it is 10 drops of liquid dish soap using a pipette. Pipettes are really simple and low cost. I see them on the shelves for under a $1 in most grow and hydro shops.5g of Citric Acid in 500ml. of water and 10 pipettes of dish soap. CL
In the photo the pipette is the plastic tube with the squeeze bulb at the end. The syringe type can also be used.