How much water should I drain ?

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AlphaMare101

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LifeTime Supporter
Jun 26, 2013
51
Fortson Georgia
I am a new member & boy am I glad I found you all!!! We have had our pool for 21 years and I am just now beginning to really learn how to easily care for our pool!! In the past, we just checked salt, ph & chlorine with "dip strips"( should be "dip sh***" lol).
Our pool was a green SWAMP for the first time in YEARS.
We (as advised by pool store) added baking soda & got ph & TA within range began shocking with ditrichlor. We have put a total of 98 lbs in the pool over the past 2 weeks. I have also used a total of (12) 3in trichlor pucks as my SWG cell died & I am waiting for the replacement to be shipped. Pool store advised flocculent, then clarifier :blah: I did this as well as daily brushings & almost daily back washings... then I found this site :whoot:
My pool is now blue, but cloudy. I can make out the liner pattern in the shallow end, but not the deep. Clearing seems "stuck" My new Taylor 2600 kit is on its way, so I'm having to rely on pool store results for the next few days. These are the results from this afternoon:
salt 2600(not worried @ this time as SWG not in use)
TC/FC 20+( they couldn't measure any higher-go figure !!said both were equal)
TA 125 (high?)
PH 7.5
CYA 100
I was told my cya was fine, which I know it's not!! She was very concerned about my high chlorine level
which I now know probably never got up to shock level. Needless to say my water is not clear.
Sorry to ramble on, but I wanted to give as much info as possible.
I now need to drain some of my water to decrease the cya level. How much(in) should I drain?? Pool is 22x42 with 3 ft shallow end & 8 ft deep end. I was" guesstimating" about 18in-does that sound right??
Any input would be GREATLY appreciated!!
 
Most CYA tests have an upper limit of around 100, so anything over 100 will still read 100, having said that 98 pounds of trichlor alone would raise your CYA by over 160 ppm, this does not count what your CYA level was at before that point, so you are likely looking at a near complete water replacement, or at a minimum around 70-75% of your water if you plan to switch to manual chlorination.

Ike

p.s. note this may need to be done as several partial drains if you have a high water table to avoid the chances of your pool floating out of the ground.
 
:wave: Welcome to TFP!!! :wave:

The problem you have is that pool store testing is not reliable ... especially the CYA test. And 100ppm is the max of most tests, so there is no way to know how much water to replace. The CYA might be 100ppm, or maybe 200ppm, or maybe 300ppm ... you need your test kit.

You could always replace 50% of the water while you are waiting, but you may need to replace more when you get your kit.

@ Isaac, I think the 98 lbs was baking soda and not trichlor ???
 
Welcome to TFP! :wave:
We are glad to have you. :mrgreen:

To confirm, no, you haven't reached shock level, which is 39ppm for your CYA level.
However, pool store testing is notoriously inaccurate and more of a guess at best.

To calculate how much you need to drain and fill to lower your CYA, use http://www.poolcalculator.com. Enter your pool volume in gallons at the top, choose your pool surface and current chlorination method toward the bottom. Then enter your current CYA under the "now" column and your desired level of 30-50 (depending on climate) :goodjob: under the Target column. Then click to the right and it'll calculate how much to drain.

Once you have drained and refilled, you need to follow the shock process. See my sig.
However, you can't properly perform the shock process without one of our recommended kits. So you should wait till it arrives.
It sounds like you are already on the right track, congrats!! :goodjob:

Be sure to stop putting pool store products in your pool and leave their advice at the door. Stick with what we have here and you'll be fine. You have a bit of a battle ahead of you, but we are right here every step of the way with you. You can do this!! :thequeen:

Be sure to read pool school, link in upper right of any TFP pg. or in my Sig.
 
Unfortunately 98 lbs of dichlor is not correct, it was actually 110 lbs!! . It has been added over the past 5 weeks,( the majority over the past 2 weeks). (1) 50lb bucket & (2 1/2) boxes of (24) 1lb boxes, plus the (12) 3in trichlor pucks. This, plus all the clairifier, & other "snake oil" we bought =$$$.
Our CYA level was supposedly 0 when we started(I hope so). So I'm guessing the CYA level is probably closer to 180-200, than 100 per the pool store.( Hoping my kit arrives tomorrow)
When I found this site, I knew the only thing I would be going to the pool store for in the future would be to buy liquid chlorine.($15.00 for (4) gal 12.5%) or "parts" I need in a hurry
I was worried about empting all of the water at once, because we do have under ground springs, but my pool is 2-3 feet above the ground @ the end of the waste hose & the "lay of the land" continues down hill . We have been brushing daily for 5 weeks & vacuuming daily the past week. I will continue to brush with each chlorine addition & emptying to as far as I can with the pump to waste (about 5 in) twice daily(before adding chlorine). Pool calculator says I need to remove 65% of my water( 3.9 ft), 26k gal :grrrr: I may use the sump? pump tomorrow & take out 2 ft.(that would be 1/2) & wait until I get my test kit to remove anymore water. Assuming the FC reading of 20 was correct, should l go ahead & add bleach to get to shock level per the pool calculator tonight?Or should I wait until after I remove water in the morning.
Thanks so much for all the advice.. I have hope again!! :p
 
I wouldn't waste the bleach taking it up to shock level. I'd start a siphon with a garden hose and let it trickle all night long. 110 pounds of dichlor would have pushed CYA to 166. Not counting the trichlor pucks and whatever residual was in there from last season. Edit: Probably 75% will need to be replaced. Do it in two increments, a couple feet at a time, to avoid trouble.

In your case, it will probably end up being faster to let the thing go green while you drain and refill and clear it later. Water is relatively cheap compared to the barrels of bleach you will need to shock a pool that size and with that high a CYA.
 

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Richard320 said:
I wouldn't waste the bleach taking it up to shock level. I'd start a siphon with a garden hose and let it trickle all night long. 110 pounds of dichlor would have pushed CYA to 166. Not counting the trichlor pucks and whatever residual was in there from last season. Edit: Probably 75% will need to be replaced. Do it in two increments, a couple feet at a time, to avoid trouble.

In your case, it will probably end up being faster to let the thing go green while you drain and refill and clear it later. Water is relatively cheap compared to the barrels of bleach you will need to shock a pool that size and with that high a CYA.
Click to expand...

I couldn't agree more Richard. :goodpost:
However, I have understood that it's bad to drain a vinyl liner pool all the way, short of a foot or 2 in the deep end. Which I don't think that's what's being recommended here, however I have also understood it bad to leave the vinyl exposed to the elements for very long. Is that why you have advised to just drain it down by 1/4 of the depth, then fill it back up & do it again?

If so, then it gets complicated where you get into the messiness of dilutions. Where in, if you had to say drain it by 1/2, but you only drain it by 1/4, you can't just do that 2x and get half. As the next drain will be only 1/4 of the remaining diluted amount, not what you 1st started with.
As an example:
Code: 
|----------------Done All At Once---------------|
|-----------------------------------------------|
 100 PPM CYA    -  50% drain & fill  =    50 PPM
|-----------------------------------------------|
|--Partial Drain & Fill @ 1/4 Drain Increments--|
|-----------------------------------------------|
 100 PPM CYA    -  25% drain & fill  =    75 PPM 
 75 PPM CYA     -  25% drain & fill  = 56.25 PPM 
 56.25 PPM CYA  -  11% drain & fill  =   ~50 PPM 
|-----------------------------------------------|
Not too horrible @ 100ppm CYA, but the higher the CYA, the more you waste in water & time, as it just compounds.
So you had to use 11% more water doing it that way. At 40k gal, that's 4,400gal!!
Is there any way to avoid this /w a vinyl liner?


As an example of the compounding, more in line with what the OP may have to deal with, it'd go something like this. Rounding shown, but actual 6th place decimals used in each calculation and rounded from there.

Code: 
|----------------Done All At Once---------------|
|-----------------------------------------------|
 200 PPM CYA    -  80% drain & fill  =    40 PPM
|-----------------------------------------------|
|--Partial Drain & Fill @ 1/4 Drain Increments--|
|-----------------------------------------------|
 200 PPM CYA    -  25% drain & fill  =   150 PPM
 150 PPM CYA    -  25% drain & fill  = 112.5 PPM
 112.5 PPM CYA  -  25% drain & fill  =  84.4 PPM
 84.4 PPM CYA   -  25% drain & fill  =  63.3 PPM
 63.3 PPM CYA   -  25% drain & fill  =  47.5 PPM
 47.5 PPM CYA   -  16% drain & fill  =   ~40 PPM
|-----------------------------------------------|

Here you used 61% more water, or instead of just over a 3/4 drain & fill, you did it nearly 1.5x over.
In water wasted, it would be 24,000 GALLONS !!!!!

THAT'S A LOT OF WASTED WATER!!! :shock: :shock:
 
Ok, I got my test kit today ..
PH- 7.4
TA- 160
FC- 9
CC- 1
CH- 110
CYA- WAY over 100 :cry: ( I diluted twice & it was still>100)

Pool calc.says I need to drain 47%- 60% of the water ( assuming CYA is 150-200) . Should I refill after draining half (20K gal) & check my CYA? How long do I need to let the pool circulate before I should expect an accurate reading? My target is 70- 80 as we have a SWG( new cell arrived today). After I get a reasonable CYA, & get everything else back @ appropriate levels after drain & refill, I will restart the shock process.
Thanks
 
AlphaMare101 said:
Ok, I got my test kit today ..
PH- 7.4
TA- 160
FC- 9
CC- 1
CH- 110
CYA- WAY over 100 :cry: ( I diluted twice & it was still>100)

Pool calc.says I need to drain 47%- 60% of the water ( assuming CYA is 150-200) . Should I refill after draining half (20K gal) & check my CYA? How long do I need to let the pool circulate before I should expect an accurate reading? My target is 70- 80 as we have a SWG( new cell arrived today). After I get a reasonable CYA, & get everything else back @ appropriate levels after drain & refill, I will restart the shock process.
Thanks
Click to expand...
Just to clarify... What reading did you get after diluting 50-50? And 25-75? and did you multiply by 2 and 4 respectively? Because the way it's phrased now leads me to think it might be 400, which means 60% is still not enough to replace.

Doesn't it rain down there in Georgia? Can't you feed a raingutter downspout into the pool? Get some free rain that way?
 
I retested my CYA & I did the dilution wrong the first time. I was diluting with sample, not tap water :crazy: . When I diluted 50/50( 1/2 first mixture 1/2 water) the reading I got was 80. So this would mean my CYA is about 160,right?
Richard, I wish we could run a down spout extension of some sort to the pool, but we don't have gutters :( I've been watching the rain POUR from the house all week, trying to figure out a way to get it captured & to the pool. Anyone have any ideas?
 
I retested CYA. I put 7ml pool water, 7ml tap water to equal 14ml in clean test spray bottle- shook well- discarded 7ml of this mixture, added 7ml reagent to the remaining water in the bottle & shook for 30 sec. CYA read 90. Would my actual CYA be 180? According to pool calc, I need to empty 61% of the pool water to hit target of 70. Sound right?
Thanks sooo much for the continued help!!
 

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