Pumps are rated for lift, which is the biggest detail you need to investigate. The packaging and product info will tell you that. Then you need to understand headloss, which is caused by such things as gravity, pipe diameter, obstructions, friction, changes in direction, etc. What you want to do is not necessarily easy or cheap depending on the force you want. A more narrow tube propels the water with more force than a larger diameter tube. Fountain heads are cheap and widely available. They are simply a cap that has holes or divisions that redirect water flow and can increase the force of the discharge. They are attached by pushing them onto the end of the discharge pipe. They are often included with pumps. I have acquired a box full that give different spray patterns. All just cap the end of the discharge pipe. What kind of spread do you want? Any bowl or surround of the tubing or the fountain head is pretty much ornamental rather than functional unless the tubing is really flexible. Then it can help keep it in position. Filtration is important for fountains. They rely on small holes to separate the spray and propel it. Blocking part with even a bit of algae can change the dynamics with drastic results. Debris of any sort will be a problem. Water loss will be a problem with such a tall spray. Wind will redirect the water very easily and evaporation is going to be increased especially if the spread is wide. I don't know a thing about the pump you show. I've never seen it before but then I don't buy pumps a lot. Mike in Illinois may know something about it.

To clear up the green water, either erect some kind of shade device to prevent the algae from getting sunlight, or install a UV sterilizer. You can also try some carbon, just regular aquarium carbon, placed in the filter (be sure to use a container of some kind like panty hose) or in the waterfall unit where the water is flowing through it.

A picture makes a difference. This is not a "pond." It is a courtyard fountain basin. Still, we can't see it because you've got it covered. Need to show the whole thing so it can be understood in the context of its surroundings. You would not want to "fill it" since it is 2' deep and that would be a massive thickness of concrete. (The next person dealing with it who wanted to get rid of it would be really pissed!) Making a bench out of it seems feasible (from what we can see). But you would only need to create a concrete cap of some sort (not near 2' thick.) And then probably tile it to look nice.

If you bought the wash tubs new, how did you cleanse them in a fish-safe way? I am about to create a 2-washtub fountain in my own backyard, with a solar power pump. Do I have to have fish, or do the small pumps move the water around sufficiently to prevent mosquito infestation? I want birds to be able to safely drink the water. I would think the murky water could be parts of dead plants or fish excreta. Perhaps the circulation in the cloudy tank is less active than the 2 clearer tanks.