Use of rainwater to dilute cya

Jul 10, 2016
21
College Station
#1
Hi there,

The last 2 seasons I have been using 12 pct bleach to maintain chlorine. Everything is great but I’m not a big fan of buying bleach all the time. A week ago I installed a 550 gallon rain barrel that collects rain from my roof. The barrel has line that can be turned on to feed water into the pool.

I did this because during summer I am constantly adding water to the pool, but the water in my area is really bad. High alkalinity and high calcium. The rain collection is effort to minimize having to add city water. I figure it will add another 30 pct or more water going into pool. I could up this higher by adding another barrel to another downspout. Another benefit is rainwater is low ph so I don’t have to add as much acid.

I was wondering if I just always had the rain line turned on ( even over winter ) would it dilute enough of the cya so that I could use tablets ? Maybe not every year but could alternate between tabs and bleach every other year ? Is this a system others have considered?
 

Jimrahbe

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Jul 7, 2014
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Bedford, TX
#2
Steve,

There is nothing wrong with using tablets... What is wrong is not testing so you know what your CYA level is... As long as you maintain your CYA to FC balance it does not matter where the chlorine comes from.

Adding rain water sounds like a great plan to me... Try it and let us know how things turn out...

Good luck,

Jim R.
 

duraleigh

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Apr 1, 2007
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Sebring, Florida
#3
Managing your pool with TFP methods basically means understanding what affects the parameters for which you test have on your pool and, then, what to do with the results.

You obviously understand. Pucks are fine when you know how to deal with them.

PS _ where are you getting 12% bleach?
 

domct203

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Jun 3, 2015
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CT
#4
30% of your 25K gallon pool is 7500 gallons. That would take almost 14 full rain barrels at 550 gallons each. How much rain do you get in the summer?

Could you please clarify your location? Where exactly is ‘College Station’?
 

Brentr

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Oct 18, 2009
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Jacksonville, FL
#5
steveik, directing the downspouts off your roof into the pool is a great idea. I did it for a couple of years as I was fighting very high CA and I did not want to lower my pool water levels. Now I am within range:cheers:
 

Donldson

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Jun 12, 2009
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NW Ohio
#6
Sure, you will constantly keep your CYA in check by constantly adding it with pucks and then diluting it with rain water, but have you considered everything else?

Pucks are highly acidic, so they require your TA to be higher to compensate. If you are burning off TA with the pucks and then replacing your water with low TA rainwater you will need to constantly add baking soda.

You also have a plaster pool so as you constantly remove calcium rich water you will eventually get too low of a calcium level. From there you will have to regularly add calcium to keep that in check.

So to me it sounds like you will be exchanging one minor annoyance for three. From lugging liquid chlorine to lugging pucks, baking soda, and calcium. If you want increased simplicity then I would use this method temporarily to bring your calcium and TA down and then install an SWG.
 

tim5055

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May 11, 2014
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Franklin, NC
#7
College Station would be Texas, home of the Texas A&M Aggies......

The problem with the rain barrel plan is that while you are adding water, the addition is to replace water that has evaporated. Evaporation does NOT remove CYA. As the water evaporates it leaves the CYA behind in the pool.

Now, if you pump 500 gallons out and replace it with 500 gallons from the rain barrel that does remove CYA.
 

Dirk

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Nov 12, 2017
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Central California
#8
Other than splash out and what one might lose during "rain exchange," does CYA leave a pool otherwise? Some posters here are claiming they must add CYA annually (like after a winter of non use). If it's not affected by evaporation, then what?
 

tim5055

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May 11, 2014
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Franklin, NC
#9
Other than splash out and what one might lose during "rain exchange," does CYA leave a pool otherwise? Some posters here are claiming they must add CYA annually (like after a winter of non use). If it's not affected by evaporation, then what?
splash out and backwashing of filters are the main losses of CYA.

There is a natural degradation of CYA, figure 3 - 5 PPM per month.

Some pools in some climates do have a large loss over winter, some suspect a bacteria or other biological that consumes it. A company now,sells,a product that claims to harness this biological process to reduce CYA, but folks who have tested it here report poor results.
 

Donldson

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#10
Other than splash out and what one might lose during "rain exchange," does CYA leave a pool otherwise? Some posters here are claiming they must add CYA annually (like after a winter of non use). If it's not affected by evaporation, then what?
CYA is very very slowly broken down by chlorine. Typical year-round pools can expect around 5 ppm loss per month on average. Pools that close for the winter have 20% or so of its water drained before closing so that drops the CYA right off the bat. Then over the winter, it can break down slowly, but occasionally it is also consumed by a strain of bacteria. This converts the CYA to ammonia. Sometimes the nitrogen process continues and the ammonia is then converted to nitrate so the owner just opens to magically disappearing CYA. Less often the process is not complete and the owner is left with a pool full of ammonia which takes a significant amount of chlorine to remove from the water.

BioWish has tried to harness this bacteria in their CYA reducing product. The results have been less than promising.
 

Dirk

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Nov 12, 2017
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Central California
#11
I fooled around with topping with rainwater from gutters, including draining first. I didn't like what was coming off my roof: some CH, some TA, and who knows what else (Yah, I'm talkin' to you, pigeons!). I know my volume, and I know I've put in CYA that should be no more than 70, according to Pool Math. So with the rain-swapping, I should be somewhat lower than 70. (My somewhat lower CH confirms this notion.) But my CYA is testing what looks to be between 75 and 80! So confidence in my CYA testing and the actual level still eludes me...

:testkit: