This is the most sought after cleaning supply that almost every household has for good. Its cleaning capacity has long been established and there are no doubts about it. With that said, cleaning your shower with baking soda; should not come as a surprise for sure. That is correct and all you need to do is to follow simple procedures for accomplishing your goals.
There are many corrosive products that are out there claiming to blast away calcium, lime and rust (catch my drift?) which I’d never allow in my house.  Certainly, all you need to dissolve this build up is a good soaking in some plain white vinegar.  The acids in vinegar naturally break down limescale and rust and allow your shower heads to work like new again.  You can also use this trick for cleaning and unclogging faucets.
I agree with Lynn’s tip about the spray and walk away foaming-type products. I tried them all and I finally found a winner. My water spots were really severe and a friend told me about Bruce’s heavy duty brown, a paste that you wipe on and rinse off. Now the water just rolls off the glass instead of sticking to it. Ace Hardware has it and it’s only like five bucks.

Here is what you can do, make a paste of baking soda with warm water. Wear a pair of gloves to protect your hands as baking soda is abrasive by nature and apply this mixture on the shower head. Our advice would be not letting it sit longer and then cleaning it with a soft cotton cloth. Remember to rinse it thoroughly with water and then see the magic!
Start by opening a window or door to ventilate the room, then grab your favorite tub-and-tile spray cleaner, like CLR Fresh Scent Bath and Kitchen Cleaner ($15, "Work on the shower in three vertical sections — this will cut down on fumes and prevent the cleaner from drying before you wipe it," says Forte. Spray the first section, covering both tile and tub, and give it a few minutes to penetrate. Then spray the second section, and let it soak while you clean the first.
Taking a shower is something many Americans do every single day. Sometimes multiple showers in a day! But, cleaning your shower doesn’t happen every day, and when it does, it likely avoids cleaning the shower head! With all the spray holes, tiny spaces between, and hard-water build-up and grossness, we avoid it, and just deal with whatever water pressure it puts out.

“Leftover wine” is stale wine. The reason leftover/stale wine can be used as a cleaner (and fresh wine can’t) is because of the air exposure time – when a bottle of wine is opened, the wine is exposed to the air and begins to oxidize (combine with oxygen). As it oxidizes, it will become more acidic and eventually turn into vinegar, often within a couple days. Ways that people use leftover wine (rather than pouring it down the drain since it now tastes stale/like vinegar) are usually as a substitute for vinegar, like for a salad dressing or as a cleaning solution. In other words, you wouldn’t go buy leftover wine; you would buy vinegar. But if you happen to have any leftover wine, this is a way to use it. If you have a neighbor who likes wine, they might have some on hand. Otherwise, you can drink a portion of a new bottle and wait a few days to make your own leftover wine.
Fill a spray bottle with undiluted lemon juice; add a couple drops of dish soap as a surfactant if you want but don’t overdo it; it’s the lemon juice that does the work. Spray all surfaces repeatedly (letting it soak after each application), until you see some results. When you first start, it will appear to have no more effect than spraying water, but, eventually the stains will start to “run”. Once the lemon juice has loosened the scale, you can use a non-abrasive scrubbing pad with Soft Scrub or Bon Ami to remove it.
The next step is to soak the showerhead in a cleaning solution to dissolve the clogs. If you were able to remove your showerhead, you can soak it in the smallest container that is large enough to hold it. If the showerhead is still attached, you can use rubber bands or a zip tie to fasten a solution-filled plastic bag around the showerhead to get the job done.

how to clean a shower head