How can you unplug the main drain pipe in your pool?

I have had mine to clog to the amount of trees in the yard. All you have to do is take your garden hose to the exit point of the drain. Wet a cloth put the hose in the end wrap the cloth around the hose. As tight as you can. Turn the water on. It is pushing in the other way. It has always worked for me.

I usually use a "Clog Buster". It's a rubber bladder that connects to a water hose and it will expand to the size of the pipe then flush water through the pipes. You can search google for "Clog Busters" and find 'em usually. Also, home depot and lowes carry them as well.

When I purchased my property the fibreglass pool had rust coloured marks in various places on pool floor. I tried diving and using a pot scourer to remove them..but to no effect as both air and energy quickly ran out. The only solution was to completely drain the pool to get right down to the problem. Now I thought that draining the pool was to be as simple as "pulling out the plug" as one does when emptying the bath at home. Not so! For some reason that escapes me, when I unscrewed the plastic outlet plug, the pool proceeded to backfill with foul smelling sandy water up through the plughole ! Now why would a pool have an outlet hole which just interfaces the underlying ground surface of the pool instead of having an outlet pipe connected just like a household bath through which to drain out the water using the pool's own water pump? You tell me? As if this wasn't worrying enough, I noticed that as I walked down to the depest end of the pool I felt unsteady on my feet as if I was becoming ill and going fall over at any minute. I did begin to feel queezy because the sensation was like that of seasickness...an if you've had that you know exactly what I mean! But No! I wasn't ill at all for as I retreated up the slope to the shallower part of the pool I felt perfectly ok again! Now I really was confused. How could I feel so sick in one place and not another! So, I gingerley started stepping forward again down towards the deeper end of the pool. Whoah! Whoa! there comes that crazy day feeling again ! I took one step back while looking down. And guess what? The whole pool floor was actually flexing up and down in a wave like motion as I walked upon it. I looked at the drain hole and with every step I took the sandy water would swoosh up from the drainhole and when I stepped back it was be drawn back down again into the plughole! What a joke! This could only mean that there was a pool of water of indeterminate size and volume under the pool proper. Anyway I had to use the pool pump to suck the water out of the pool as low as the vacuum hose extension would allow me to. Then I rigged up a small 240volt water pump from an old backyard water fountain system with a washing machine hose and a length of garden hose attached to suck out some more. The final dregs were taken out using a plastic dustpan as a scoop to put the last drops into a bucket. Phew!...it was a sunny day of about 25 degrees celsius, but inside the pool was like being in a kind of enclosed oven. This took me a whole day and I was exhausted. Next day I diligently set to using dampened fine wet or dry paper to rub the pol surface to remove the rust stains, and at first it worked a treat. Then I found that I had been working on the SMOOTH fibreglass surface area. Yep! you guessed it life wasn't meant to be easy for for a "do it yourselfer" like me. Now I had to tackle the stippled fibreglass surface area, and yep, you guessed that one too........this was where the majority of the big rust stains were! Is pool ownership such a good idea? I found myself endlessly and punishingly asking myself ! Now I was down to using a toothbrush and Jif paste cleaner to try and remove the rust stains. On the stippled surface I found it very difficult. It was a bit like trying to scrub an deeply piited orange peel. In the end, I settled for a small improvement attempt then gave it up as a bad job! OK so now I had an empty pool with some scuffed out markings in various places on its bottom. T Don't laugh !...........can you guess? Yep, that night it rained quite heavily! As our Australian sunshine State of Queensland is currently badly drought affected, the news bulletins had a field day RAVING ON ABOUT THE WONDERFUL DOWNPOUR, which although welcome, would do little to change the newly imposed water use restrictions. Can you guess what this Do It Yourselfer was screaming out loud all day? You can? OK so there's no need for me to print the filthy diabolical diatribe! Now like most of you I have stumbled onto this site as I search in vain for some hero to give me the freebie info I need to remedy the water table problem I have. You know the next time you have a bath, I want you all to say a prayer for the smartass who invented the 100 liter home bath plughole ...with a downpipe..so that ignorant do it yourselfers like you and me could simply pull a plug and have the unwanted water drain away to a place..who knows or cares where ! Then I want you all to set up your candles and voodoo gear and Satanic ritual stuff, and Yep!..you guessed it ... Put Beelzebub's Curse on the twit who thought the best way to empty a 30000 litre swimming pool was with a hole directly into the ground underneath it!

Just be thankful that after you pulled the plug that your pool did not float out of the ground once the pool was even partially empty. I just cannot imagine what fowl things would exit your head then. The "Main Drain" unlike a bath tub is meant to draw pool water from the bottom of the pool for better circulation throughout the pool. It's connection goes directly to the skimmer and then directly to the pool pump. Great story LOL. Another reason to not hire a house plumber to plumb your pool

Yikes.... concerning the second answer...

The main drain has two pipes. One leads directly back to your pump/filter and is the proper one to use for expelling water from your pool. You simply shut off your return valve and open your backwash valve and water will be pumped out of the pool. There is nothing to be done to the main drain at the bottom of the pool. There is NO "pulling the plug". ...Alternatively, you can rent a commercial submersible pump if you want to drain the pool quickly.

The second pipe (the one opened by the afforementioned answer) is a hydrostatic release valve. It's purpose is not to drain the pool!!! It is to release pressure from ground water residing underneath the pool (explaining the foul sandy water entering the pool when opened). This valve needs to be opened when draining the whole pool to prevent the pool from cracking or popping out of the ground. When you drain the pool is can become very much like a boat and will want to float on top of the ground water beneath.

Your quite lucky that you didn't crack your pool or watch it rise from the ground!!!