1. Soak in distilled water + vinegar or citric acid for about an hour or so.
2. Flush
3. Soak in distilled water + backing soda for about an hour or so.
4. Flush
5. Wash extensively in distilled water.
6. Done

its better to have 2 tanks, one for color and one for B&W, thou You still have to clean them from time to time.
Plastic ones at some point will get more hassle to clean up.
Stainless Stell are ok, well, most of them. Usually the reel is very under-engineer thing.. but You cant have it all in one package