1.More often than not, above-ground pools have a shorter runtime need. This is purely because of size - above-ground pools are usually smaller than in-ground pools. With a smaller size, the turnover rate is shorter because there is less water to be circulated and cleaned. 2.I heard someone once say that if you run your pump twice as long one time, you can skip running it the next time you normally would. This just isn't really how it works. Running it longer than necessary may not have any positive impact, and it certainly won't carry over into the next regular runtime. 3. When a pool is green/cloudy, it is a good idea to run the pump for 24 hours straight. But, that's not the first thing you want to do. First, you'll want to brush the sides and bottom of the pool and then shock it. Then you can run the pump for at least 24 hours or until it looks clean. You will also want to test the water's pH and levels, and you may need to clean the filter.
That's an insightful question about system maintenance. While my trade is roofing, the principles of long-term efficiency and system stress apply just as much to pumps as they do to attic ventilation. My advice on runtime does not significantly change based on whether the pool is above-ground or inground. The primary difference is simply the volume of water being filtered. An above-ground pump may be smaller and the plumbing less durable, but running a small, stressed motor constantly is just as poor an engineering decision as running a large one. Continuous use causes premature wear on the seals and bearings regardless of pump size, trading long-term reliability for short-term clarity. The goal for both is efficiency, not endless runtime. The dumbest 'hack' I've ever heard someone give about pump runtime is, "Just run it continuously and turn the temperature way down to slow the pump's motor wear." This ignores the fact that while continuous use might wear out mechanical parts, intentionally over-cooling a system is wildly inefficient and wastes massive amounts of energy. It's like leaving your roof ventilation fan running 24/7 in January to "cool the motor." It completely misunderstands the cause of failure and the cost of the operation. When a pool is green with algae or extremely cloudy, "run the pump 24/7" is almost never my first instruction. That's a brute-force approach that ignores the core problem. My first instruction is to chemically shock the water and clean the filter—the equivalent of treating the mold and scrubbing the surface before you worry about the ventilation. Only after chemical treatment and cleaning do we run the pump continuously to circulate the treatment. We tell them to stop the continuous run when the water achieves perfect clarity and the chemical balance stabilizes, returning to a standard six-to-eight-hour cycle. The solution is always precision chemistry, not perpetual motion.
Yes, I would say it's better for a smaller pump to run for a shorter time in general, because they will tend to wear out faster in my experience. This tends to work okay because an above ground pool will not tend to have the volume of water of an inground pool, so a smaller pump can work just fine to filter the water. I definitely wouldn't recommend running an above ground pool pump 24 hours a day, since I do think you'll wear through the motor much faster this way. If your pool is super cloudy my first advice is often going to be to check your water conditions/pH. Of course, it's also a good idea to get that pump up and running to start clearing things out, but you're unlikely to solve the problem using the pump alone. More likely you will need to disinfect your water, adjust your pH, etc, to get it back to normal conditions.