The problem with that is that most in ground pools drain through the skimmer at the surface of the water. sot the thing to do it get a hose connected to the skimmer intake, taking care that not too much air gets into the system, and throw the end of the hose on the floor of the pool. so long as no air robs the system of prime and you have a reasonable pump you should be able to empty it. It would be wise to keep an eye on it as you are doing this. ( You wouldn't want to wreck the pump) a safer way is to hire a submersible pump to do it.
Closed
Vacuum the pool. If you have to drain it, only drain it half way. Floating pools are a disaster.
Why would you drain your pool just becasue the water is hot? Never drain your inground pool unless you have first cut holes in the bottom of the pool to keep it from floating. If the water table in your area is high enough, your inground pool could "float" out of the ground, effectively ruining your pool.
Filter it then swim in it.
Hmmm, do you possibly mean the back wash valve on the filter? This valve has many positions to choose from especially for sand filters. Filter, back wash, drain, drain to waste, filter bypass, closed. They are pretty much self explanatory. Normal position would be the "filter" position while the pump is running and the filter is working. Ken
NO!
You need to vacuum the mud to waste. ie: vacuum not through your filter as you normally would, but using a separate pump and discharging vacuumed mud/water to waste (somewhere other than back into the pool).
Need to rephrase question.
Justin Bieber has a inground pool
To effectively detect an inground pool leak, you can use specialized techniques such as a pressure test, dye testing, or electronic leak detection. These methods can help accurately pinpoint the location of the leak in your pool.
Most likely bubbles that do not actually use soap. There are many formulas that you can mix up to make bubbles. Try finding a combination that won't ruin your pool filter and if possible, keep you from having to drain the pool.
The rainwater will be treated by the chlorine in the pool and you may have to adjust the chlorine levels. See the related link for more information.