Google Hydraulic cement (HC), you should be able to purchase 5 lbs or so for less than $20.
Tools needed: 2Q bucket (dont expect to be able to clean it 100%), margin trowel (for mixing and scooping), 3" putty knife, rubber gloves, paint scraping implements (goggles, if you use a wire wheel)
- Remove as much of the paint as possible, especially in the bowl area.
- Dampen the area. Residual water is not a problem for HC
- Following package direction, mix a small amount(1lb) of HC and working quickly (you only have 3-5 min for most versions), push a handful into the suspected bowl area. Smooth and taper the "plug".
Test the bowl immediately. The nice thing about HC is it can even be placed underwater and will cure. This treatment will work below the bowl, also. Be sure to carefully remove any loose cement, as well as paint
If the patch is not working well enough, a masonry waterproofer (to be distinguished from a masonry sealer) would be the next step. I can personally recommend the Drylock brand (no financial connection). The powered version
is nice because you only makeup what you need. It is paintable, so the whole fountain can be redone.
The company's recommendation for the paintable waterproofing is to etch the surface if efflorescence is present. Efflorescence is a whiteish deposit on the surface of masonry that are a combination of minerals. The minerals will interfere with the waterproofing binding to the cement. You can try to dissolve it with 100% vinegar. If that doesn't work, you can use either their etcher or muriatic acid. This is a highly caustic, acidic product. You need hand, eye, lung, hair and clothing protection from the concentrated liquid (treat the diluted form with great respect, also). US Government data sheet on Hydrocloric acid
Outdoors is a given, a box fan is helpful, acid rated, charcoal activated respirator, water hose, box of baking soda for any spills. Thoroughly wet the fountain and the rinse off area.
It must be diluted by the following method:
Add the acid to the water in a bucket (NOT the water to the acid) This will minimize the reaction and safely dilute the acid without boiling. Most etching recommendations suggest a 10:1 dilution (10 parts water to 1 part acid) This would be starting with as 30% HCL Muratic acid. Increase the starting water as necessary if your Muratic acid is more concentrated.
Allow the acid to work for the recommended time (The salts should disappear in 5min or less.) Then you can neutralize with a gallon of water with a box of baking soda (you might just have this on hand ahead of time). Follow with a water rinse. Allow to dry overnight and then coat with the Drylok.
On the plus side, its a (seemingly) well adhered horrible color. That means recoating it another color, will be a fruitful effort.
Buy the best coating you can afford. Horizontal, exterior surfaces receive the harshest conditions. An anti-slip additive will be money well spent.
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To secure the base of the steel support you can use a concrete screw. TapCon is a ubiquitous brand TapCon screw that has worked well for me. You will need to drill into the concrete with the correct size bit (5/32" or 3/16") to accommodate the screw length.
Another fastener type (Redhead is one brand) Redhead bolt is one in which after drilling a proper sized hole the fastener is inserted and then sharply struck with a hammer. The force of the hammer drives a metal shield around the bolt to expand outward which wedges the threaded post rigidly in the concrete. The machine screw threads can be used to fasten the base with SAE nuts. Lastly, you can drill an opening in the concrete and insert a lead shield. This is basically a HD wall anchor. After tapping into the concrete a bolt is tightened into the shield it will expand to tighten against the wall of the hole.
Using a hammer-type drill with a masonry bit will facilitate the job of drilling into the concrete. I found when using expansion-type bolts that vacuuming the dust from the hole enables the expansion shield to hold and stay wedged as it is being tightened.