Used this first with TSP. Mixing the TSP with hot water and dissolving it completely posed no problem for the sprayer. There was never any leakage (see why below). The handle was comfortable to hold. Jet setting was way under the power of my ordinary hose nozzle so I'm going to look into removing the restricting valve at the hose connection of the sprayer. May not be possible without damaging the unit. We would have liked more power than what we get as is. Mix setting dial was easy to use and with a little experimentation we were able to adjust the concentration very nicely. Update: it is possible to remove a portion of the flow restriction valve, and it does increase the power and distance of the jet spray without interfering with anything else. There is a small plug-like insert where the hose connects. Remove it carefully because you will be putting it back. With the valve removed proceed to remove the astericks shaped restriction from the valve 'plug.' I used a small knife to cut through the projections. Once removed replace the plug back into the handle as it's essential to seal the connection with the hose.
Also I found why I had no problem with leaking at the handle as described by others. I inadvertently had two seals in place of the one which comes with the unit. It did leak when I removed the extra seal so there are two seals in the unit now.