In my experience, most horror stories of pool maintenance are usually the result of neglect, or not paying attention to the instructions. It's not that hard, but expect to spend an average of 10-15min per day checking on your pool, adding chlorine, clearing out leaves in the skimmer, etc. Also, once a week, expect to spend some extra time brushing/vacuuming the pool and cleaning the filter.
As a first time pool owner, the simplest thing you can do is pick up a free pamphlet on pool care. Follow the instructions in the pamphlet, and make sure you stay on top of it. My Wal-Mart usually has pamphlets by HTH Pools next to their chemicals.
Start by getting a test strip kit. You dip the strip in the water and compare the colored pads against a chart. Pretty easy (unless you get into a fight with your wife about the shade of orange of the pH pad).
Make sure you pick a good test kit, which measures several properties of the water (should measure pH, stabilizer/CYA, alkalinity, hardness, chlorine). Cheaper ones will only measure a few properties.
Measure your pool every day or so. If the levels are off, adjust them by adding the appropriate chemicals. Just follow the instructions on the container. Most any chemical you need can be found at your local pool store, or Wal-Mart. Beyond that, I'm not going to repeat what you would find in the pamphlet. (Did you get one yet?)
One bit of advice that wasn't in a pamphlet: If you buy "stabilized" chlorine products, they will raise the level of stabilizer/CYA in the pool. If your CYA levels are already high enough, the stabilized product can push your levels over the top. If you aren't sure if the product is stabilized, look for the words Dichlor or Trichlor in the ingredients. Un-stabilized chlorine is usually Calcium Hypochlorite or Sodium Hypochlorite.
Beyond the chemicals, there will be some "mechanical" maintenance/care:
Dirt, pollen, and algae will naturally collect in all the crevices of your pool, so use a pool brush to break it up. Regular churning of the water (from brushing or swimming) will give the filter an opportunity to suck up the debris before it settles.
You will need a vacuum (manual or automatic) to suck up non-floating debris. 48 hours before vacuuming, shock the pool to make sure any algae is dead. 24 hours before vacuuming, add some clarifier to make the algae and dirt settle on the bottom (where the vac will get it).
Make sure your filter is clean. There should be a pressure gauge on the filter that will indicate when too much crud has built up in it (pressure levels will go up). At that point, you need to clean it. Some filters are cleaned by backwashing. Others have a cartridge that needs to be changed. The filter should come with some instructions on how to care for it.
Check the strainer baskets in your skimmer and pool pump. Larger debris like leaves and large bugs will collect there. Periodically shut off your pump and scoop the crap out.
A plugged filter or strainer basket will strain your pump, and maybe cause a burst hose (very bad). So, keep the water path clear.
If you have cold winters, make sure you follow the instructions on winterizing the equipment. I disconnect my pump and bring it indoors every year.
I wouldn't tear the bathroom wall apart... I'd tear the bedroom wall apart. What you are experiencing is the noise traveling through mechanical connections to the wall (screwed to studs) and the noise from the water passing through thin copper pipe (probably the Type M pipe rather than the thicker Type L).
The only effective way I know of is to insulate that wall with Roxul Safe and Sound. It's an insulation designed for noise.... and noise only. It doesn't burn. To go the added mile, use resilient channels before hanging the drywall. The demo is probably a DIY, the installation of the Roxul is DIY, and the drywall.... call someone. For a few hundred bucks the repair will disappear.
Edit:
Blown in insulation will not work... blown in is for warmth, not sound. It's the sound transfer you're trying to conquer. We once built a house and insulated the walls with thermal insulation, thinking just like you are. It didn't work. We had the type L pipe, all the plumbing was fastened with cushioned fasteners. We thought we had it knocked. Turned out, it was a waste of money.
If you truly want to fix it, just take down the drywall and do it the right way with the Roxul. Going into a wet wall from the bathroom side is a suicide mission. Building an offset wall will create a door opening that's 10"... with a door that has a 5" jamb. Then there's the carpet... or other flooring surface. It sounds like a difficult job, but it's probably only one weekend.
Otherwise, just buy your son some foam ear plugs at Costco and call it a day.
Best Answer
I think the point to the question was to build a soundproof box more than buy a new motor, although good suggestions for power and such.
From some research on similar topic and some personal experience I have discovered that looking at the mounting of your motors is very important. Sometimes placing a rubber or similar vibration absorbent material between the motor and whatever it is standing on reduces referred vibration and low level tones that are almost impossible to sound proof. Spend time getting the low level vibrational sounds sorted out.
As for a housing, for me their was already a small brick wall around the pumps. I used ply board against many recommendations to build a housing then lined the inner area with heat resistant foam and a lightweight insulation material called "think pink" (in South Africa).
The padding is lightweight enough for me to lift the cover off to get to the pumps and the gap and ambient temperature around the pumps when sealed is cool enough for the motors. Obviously not in direct sunlight helps.
Ventilation is always an issue as direct air exposure permits sound waves to "escape" thus one must use a bit of common sense to allow more ventilation if the pump house needs it to keep the motor cool.
I would not say the rig is 100% sound proof... Yet... Our bedroom is literally right next to the motor and you can definitely hear when the motor runs. So a lot better than it was. Can't hear the motor from any other room in the house.