I use tap hot water when available or have some 25 litre containers that I can fill and take with me, just drop the solution pump hose into it. The magma will heat from cold, and perform better with warm/hot water, I don't own an in-line heater but have tried the magma and was impressed but tap hot seems to do me fine. For bad traffic lanes on synthetics try a Heavy Duty Splitter like HDX, Prochem Ultrapac or powerburst all with an acidic rinse subject to testing. As has been mentioned dwell is important but try not to let it dry out. You can also save on the job time by mixing pre-spray in the sprayer before you leave home.
