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Thread: How to drain water out of pool

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    How to drain water out of pool

    Hello all,

    New pool owner here. Just tested my water for the first time today. Here are the results:

    FC 10.5
    CC 0-1
    TA 130
    CH 470 ( source water 180 )
    CYA 100+
    PH 7.2-7.5 ( source water 7.5 - 7.8 )

    After reading from the Pool School it seems most of the readings are within parameters with the obvious exceptions being CYA & CH. So if I understand correctly I need to drain & replace water. Seems to me I should drain half the pool & replace. Does this sound right?

    But how to go about it? When I backwash the filter, I'm obviously replacing some water, but I need to drain much more. Specifically below the skimmer...

    There is a stop on the multi-port switch just before the filter that says "drain". Will this setting bypass the skimmer? I'm looking for whatever would drain from the main drain, correct?

    Thanks in advance,
    Dave
    20K gal IG plaster pool, Manually chlorinated with 6% bleach, 1.5 HP Sta-Rite Dura-Glas II pump, Pentair FNS Plus 48 DE filter, Polaris 280

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    frustratedpoolmom's Avatar
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    Re: How to drain water out of pool

    Quote Originally Posted by Beez
    Hello all,

    New pool owner here. Just tested my water for the first time today. Here are the results:

    FC 10.5
    CC 0-1
    TA 130
    CH 470 ( source water 180 )
    CYA 100+
    PH 7.2-7.5 ( source water 7.5 - 7.8 )

    After reading from the Pool School it seems most of the readings are within parameters with the obvious exceptions being CYA & CH. So if I understand correctly I need to drain & replace water. Seems to me I should drain half the pool & replace. Does this sound right?

    But how to go about it? When I backwash the filter, I'm obviously replacing some water, but I need to drain much more. Specifically below the skimmer...

    There is a stop on the multi-port switch just before the filter that says "drain". Will this setting bypass the skimmer? I'm looking for whatever would drain from the main drain, correct?

    Thanks in advance,
    Dave
    Correct, though I'm unfamiliar with your setup, I'd give it a try and see what happens. Any risk of the pool popping? Maybe drain 1/3 down, retest, repeat if neccessary? THe high CH isn't as much of a problem as the high CYA. High CH is a problem if the PH goes above 7.8.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: How to drain water out of pool

    With your CYA over 100, you can test a sample that's 1/2 pool water 1/2 tap water, and then double the result. This doubles the range of the test with some loss of accuracy, but it's not that precise a test to begin with. That will give you a better handle on how much water to replace.

    Regarding how to drain, some jurisdictions place restrictions. Where I am, I can backwash onto the ground, but to drain it has to go into the sewer so I couldn't use the pool pump for that. I bought a cheapo sump pump from HD. (Took a week to drain far enough, but it wasn't worth getting anything heftier as mostly I will use it for draining the hot tub which takes <1hr.) If your area has this restriction, you could probably rent a pump for less money.
    --paulr
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

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    Re: How to drain water out of pool

    Thanks for the speedy replies, y'all!

    Quote Originally Posted by frustratedpoolmom
    Correct, though I'm unfamiliar with your setup, I'd give it a try and see what happens. Any risk of the pool popping? Maybe drain 1/3 down, retest, repeat if neccessary? THe high CH isn't as much of a problem as the high CYA. High CH is a problem if the PH goes above 7.8.
    Don't know what "popping" is...maybe the pool popping out of the ground? If so, I would think that's not very likely, but what do I know? I've never drained a pool!

    Quote Originally Posted by PaulR
    With your CYA over 100, you can test a sample that's 1/2 pool water 1/2 tap water, and then double the result. This doubles the range of the test with some loss of accuracy, but it's not that precise a test to begin with. That will give you a better handle on how much water to replace.

    Regarding how to drain, some jurisdictions place restrictions. Where I am, I can backwash onto the ground, but to drain it has to go into the sewer so I couldn't use the pool pump for that. I bought a cheapo sump pump from HD. (Took a week to drain far enough, but it wasn't worth getting anything heftier as mostly I will use it for draining the hot tub which takes <1hr.) If your area has this restriction, you could probably rent a pump for less money.
    --paulr
    Good idea on the CYA test, Paul! The pump already backwashes into the sewer, so if the "drain position" works, it will drain into the sewer as well. Guess I'll give it a try... Wonder how long it will take to drain half the pool?

    Dave
    20K gal IG plaster pool, Manually chlorinated with 6% bleach, 1.5 HP Sta-Rite Dura-Glas II pump, Pentair FNS Plus 48 DE filter, Polaris 280

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    reebok's Avatar
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    Re: How to drain water out of pool

    I don't have one of these types of filters, but is your drain setting simply a pvc that water shoots out of? if so, you can use this formula:
    Q = 29.7 x D2 x √ P x .9
    d2 is the diameter squared (the diameter of the pvc pipe...I'm assuming it's just an open pvc pipe, but if you can show me or explain better, it may be a slightly different formula)
    √ P is the square root of the pressure. this will be dependent on if the pressure gauge reads when you're dumping water or if you can find out from your manual or something.
    Q is gpm.
    so for example, let's say you have an open 2 inch pvc pipe that the dump water comes out of and it goes at 10psi.
    Q=29.7 x (2)2 x sqrt 10 x .9 = 338gpm
    you have a 20K gallon pool so 20K/338 = 59.1715976 which is about an hour to drain the whole thing, or 30 minutes for half.
    again, these numbers are just totally random, you need to know your own numbers to be able to use the formula. or just sit there and watch ;)
    16x32 21,000 gallon in-ground exposed aggregate, 1.5hp pump, 120 sqft catridge filter, birdcage, solar panels, aquavac tigershark qc robot.

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    launboy's Avatar
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    Re: How to drain water out of pool

    Quote Originally Posted by Beez
    There is a stop on the multi-port switch just before the filter that says "drain". Will this setting bypass the skimmer? I'm looking for whatever would drain from the main drain, correct?

    Thanks in advance,
    Dave
    Just turning the handle to drain on the multiport will not shut off the skimmers. It will send thewater out the backwash pipe though. To drain below the skimmers, you'll need to find out how to shut them off. Do you have a couple of valves before the pump(suction side) or do you just have one pipe coming out of the ground? If you have valves, or a 3 way valve, then you need to figure out which one controls flow to the main drain, and shut off the rest. If you only have one pipe, it might be a bit more complicated.

    Oh, and yes, when they say popping, they do mean your pool literally popping out of the ground. This can happen if you drain the water out below the water table. If you KNOW you have a low water table, you can drain most of the water, but if you know it's high or have no clue, you can't. Most people will say don't drain more then 6"- 1/3" of the depth, it all depends on how much of a risk you want to take.

    HTH,
    Adam
    18' x 42" Intex Easyset Pool, with 16' x 52" deep end in the middle. Approx. 5500 Gal.
    Hayward Power-Flo LX 1 HP, 100# Jacuzzi Brand Sand Filter(Piped underground so it looks nice) 8)
    3 - 2' x 20' Solar Pool Heater Panels(roof mounted)
    Goin' on 9 summers...NOBODY thought it would last this long.
    Buried Portable Spa sharing pumps and water with pool (Almost complete project)

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    Re: How to drain water out of pool

    Well, I was wrong on two counts. For one, the multi-function valve does NOT read "drain" it reads "WASTE". Secondly, as Adam points out, that setting does not shut off the skimmer. One of the valves might shut it off, but how do I know whichy one? Should I shut each one off, one at a time, until I get the desired result?

    I noticed that the drain at the bottom of the pool was not doing anything. Again a valve issue?

    Would it work to put a garden hose in the pool while running the pump to waste? It seems like that would take much longer because I would be diluting while draining...

    Dang, nuthin's easy...

    Thanks for all the help,
    Dave
    20K gal IG plaster pool, Manually chlorinated with 6% bleach, 1.5 HP Sta-Rite Dura-Glas II pump, Pentair FNS Plus 48 DE filter, Polaris 280

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    launboy's Avatar
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    Re: How to drain water out of pool

    How many valves are there on the suction side of the pump? How many skimmers? The main drain(s) should only be one valve. Easiest way to figure out which one is the main drain valve is to have the pump on and turn a valve. Go check for flow in all of the skimmers, if one is no longer flowing, the valve controls that skimmer. Do this one by one until you turn a valve and all of the skimmers are still flowing, this is probably the valve that controls the main drain.

    Try that and let us know what happens.

    "Waste" is the same as "Drain".

    Also, you can use the hose to fill and pump water out at the same time, but like you said, it's not as efficient, and you will have to stop to refill every once in a while because the pump will remove more water then the hose can fill.

    Adam
    18' x 42" Intex Easyset Pool, with 16' x 52" deep end in the middle. Approx. 5500 Gal.
    Hayward Power-Flo LX 1 HP, 100# Jacuzzi Brand Sand Filter(Piped underground so it looks nice) 8)
    3 - 2' x 20' Solar Pool Heater Panels(roof mounted)
    Goin' on 9 summers...NOBODY thought it would last this long.
    Buried Portable Spa sharing pumps and water with pool (Almost complete project)

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    Re: How to drain water out of pool

    Well, I give up. By turning the two 3 way valves I was able to successfully drain the spa, and I did figure out how to turn off the skimmer, but I could not activate the main drain.

    I'm going to go the slow route fill and drain simultaneously.

    Thanks for the help,
    Dave
    20K gal IG plaster pool, Manually chlorinated with 6% bleach, 1.5 HP Sta-Rite Dura-Glas II pump, Pentair FNS Plus 48 DE filter, Polaris 280

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    frustratedpoolmom's Avatar
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    Re: How to drain water out of pool

    It's entirely possible the main drain was sealed off at some point because of leaks. How old is the pool?
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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