There is no filter at the bottom of a pool. Perhaps you are looking at the hydrostatic valve which is there in case your pool is emptied and Will make sure that the pool wont float in ground water.
The cleaning schedules varies from filter to filter, but a general guideline on any swimming pool filter is to take a reading when the filter is clean, then clean the pool filter when the pressure rises about 10 psi.
If you use a test kit and your chlorine level is high I would say no, let the filter run and while the filter is running vacuum the bottom of the pool to remove some of the mud off the bottom of the pool floor and check the filter for high pressue, so the filter can do its job and get the pool clean. You want to keep your chlorine level above normal during the cleaning level so when the pool is clean your are ready to use it, also I do not know how brown or muddy the water is.
Clean and empty in ground pool filter, clean and empty filter near pool pump. Be sure all whips are clear of dibris. also do a flush of the system. If this does not help, you will need to have a C02 charge done between the pool line and the pool pump. OR you may need to have your impeller replaced in the pool motor.
The closest you can come would be to use a floculent to settle the dirt to the bottom and then vacuum the bottom layer of water to waste.
No
No , if you have a D.E. filter instead of an older cartridge filter than the D.E. can get pretty messy if when you filter clean , and if you have a backwash when you backwash .
If you are getting sand coming into the pool and have a sand filter you may have to replace worn laterals in the sand filter.
No you only backwash your pool when your filter pressure on your filter is high 30psi and above on most pools. If you backwash your pool be sure to add two scoops of de to your skimmer. If the presure is still high the u need to clean the filter
There are ways to clean without draining or running through your filter but they would include the use of a separate filter which would be as much hassle.I would recommend draining the pool and lightly acid washing to properly get out all the mud and bacteria it may have left behind.
If you are backwashing more than you care to,or your filter pressue is high, or you put your hand against the outlet where the clean water is returning back to the pool and your hand does not get pushed away any of these reasons would be a reason to change the sand, depending on the size of the filter some filters need to be changed once a season every other season or not for years, bottom line you should only be backwashing after vacumning the pool. if your water in your pool is clean or clear I would say the sand is ok.
Alum is a floculent and these are often used to settle excessive amounts of dirt to the bottom of pools the are available from pool shops. It sounds like you will need to replace the laterals in your sand filter first so that you don't have this problem in the future. Take care vacuum the settled dirt and flock to waste do not put it through the filter.
Keep your pool water clean is a very challenging task. You can use some pool supplies like Dust Net, Water filter, water vacuum cleaner for remove dust from surface, etc. Keep switch on your water filter for 24/7 hrs for cleaning water or remove small dust particles from the water. Clean your water filter after every 7 days it makes clear passage through the filter, it helps your water clean regularly. If you do not clean your filter then your filter get chocked up and water will not pass through the filter. You can chlorinate you pool water it also help to keep your pool water germs free.