Originally Posted by USNA94

I used to use the Mr. Clean Car Wash nozzle and it was actually pretty good about not leaving spots as long as you kept a fresh filter in it. But I could only get about 5 washes out of it before its indicator changed brown telling me I needed to replace the filter. For what I was spending on a year's worth of those disposable filters I bought one of these:
Garden Hose Water Softener Canister

$48 for the water softner canister and another $21 for the filter insert.

Another $5 worth of water softner pellets from the supermarket allows you to recharge the filter insert for about 20 years or so.

You just put it between two lengths of hose and works like a charm.