I usually put about 2 inches in mine
I remember way back early 00’s on Autopia that was the recommended amount.
The thickest foam I’ve ever used is Meguiars Hyper wash, but thickest isn’t always best as you want it to be fluid enough to lift the dirt and fall to the ground.
I think you need to up your dosage, you need to think about the amount of water being drawn from the power washer and mixing with your 5% foam you have in the 1 litre bottle
I remember way back early 00’s on Autopia that was the recommended amount.
The thickest foam I’ve ever used is Meguiars Hyper wash, but thickest isn’t always best as you want it to be fluid enough to lift the dirt and fall to the ground.
I think you need to up your dosage, you need to think about the amount of water being drawn from the power washer and mixing with your 5% foam you have in the 1 litre bottle