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Thread: pH is low, but adding soda ash clouds the water with silt

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    pH is low, but adding soda ash clouds the water with silt

    Hi all. I found this site via google searches for this problem. After reading a few posts I was convinced to buy a TF-100 test kit to understand what my pool chemistry is doing and to be able to ask intelligently for help on this forum.

    Each spring I open the pool and try to get the pH up to the correct level. However, it takes a lot of soda ash to move the pH just a little. Also, when I add the soda ash, the water clouds and silt forms on the bottom. Vacuuming it up clogs the filter quickly and I have to backflush to get rid of it. I am trying to find a way to get my pH right without the clouding.

    After reading advice in other posts, and seeing the results from my tests, my high school chemistry flooded back to me and I realized by adding soda ash (sodium carbonate) I am adding carbonate ions to the pool, which is combing with calcium and precipitating out (calcium carbonate or chalk). My question is, is there any way around this? Will the problem be better if I use borax instead? Is there any other safe chemical I can add that will not precipitate out the calcium? Is this damaging the plaster in any way?

    I am in Portland OR, I have a sand filter and plaster pool. 17,300 gallons. Results of TF-100 tests below.

    TC > 5 (too yellow - off the charts)
    pH 7.1
    FC 4.5
    CC 0.5
    CH 500
    TA 200
    CYA 100

    The chlorine was low before i took these measurements, so I added 8.25% bleach. Unfortunately, I thought my pool was larger than I actually is and the pool calculator instructed me to add too much bleach. Now my eyes are burning from my afternoon swim and I am waiting for the chlorine to drop. Measured the pool size and came up with an accurate number of gallons, I hope.

    Looking at the results from plugging these numbers in the pool calculator, I may need to replace some water in order to get the CYA as a reasonable level. Reluctant to do that due to possible drought coming this summer and I hate to suck up the water. Advice appreciated.

    Thanks!

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    Re: pH is low, but adding soda ash clouds the water with silt

    welcome, you found a great site and we will get you going... could you please fill out your signature so we can see what type of pool and equipment you have, it will help everyone.. click setting top right and about half way down the page on the left

    I know you think your chlorine is to high, but it is too low, you should be at a fc of 12 with a cya of 100 Pool School - Chlorine / CYA Chart but the cya test stops at 100 so it probably needs to be higher than that..

    your CYA is high, and unfortunately the only way to get rid of CYA is to empty water, but first we need to find out really how much CYA you have... the following test is not exact but its close enough to see just how high your cya is to see how much you need to empty. (you will probably have to empty at least half of your pool, sorry, I know this is the last thing you want to read)

    extended CYA test, the 8th post down Extended Test Kit Directions
    basically your using half of the mix and multiply it by 2


    Someone will be along to respond why your eye's are burning, I have read about it but just cant remember...
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    Re: pH is low, but adding soda ash clouds the water with silt

    Use 20 Mule Team Borax to raise your pH.....problem solved.

    Your eyes did not burn from an FC of 4.5 at all. I do not know why they did but it wasn't from the FC.

    Actually, with your CYA of 100+, your FC should be up around 8-12 ppm ppm.

    Sooner or later, you will have to address that CYA of 100+. It makes your pool almost unmanageable. Couple that with your CH of 500 being really too high and I suggest a 50% drain/refill to get your pool water inside the parameters we suggest.
    Dave S.
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    Re: pH is low, but adding soda ash clouds the water with silt

    Your eyes were burning from PH too low. I swam in my pool at least 5 hours yesterday with FC19 and CYA 70 with no burning.

    I am surprised that you need to raise PH with TA that high. Has that TA number been there a while? You are going to need to lower it after you address CYA. Pool School - Lower Total Alkalinity
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    Re: pH is low, but adding soda ash clouds the water with silt

    Low ph and cc are what will burn your eyes. I'm finishing up a mini slam because of some cloudiness. My FC was 25 yesterday and no-ones eyes were burning.


    30K gallon IG vinyl. 1.5HP 2-speed Waterway Mustang pump. 600 lb sand filter. Polaris 280. Circupool SI-60+. TF-100

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    Re: pH is low, but adding soda ash clouds the water with silt

    Thanks all. I will do the extended test for CYA. Quick responses below.

    Yesterday I added 128 oz of 8.25 household bleach. No issues with burning eyes before the addition, now I have them.

    Was trying to increase pH from 7.1 to ideal range 7.4 or so because I understood that was important to maintain other chemistry. I have not read that with a high TA this may not be necessary, is this the case?

    I do not know how long TA has been high, but I expect it has been this way for years as it has been hard to adjust pH for a while.

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    Re: pH is low, but adding soda ash clouds the water with silt

    If you only need to raise the PH a little, perhaps aeration would be a good way.
    26' X 52" Intex Ultra Frame. Intex Sand Filter
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    Re: pH is low, but adding soda ash clouds the water with silt

    Quote Originally Posted by cowboycasey View Post
    your CYA is high, and unfortunately the only way to get rid of CYA is to empty water, but first we need to find out really how much CYA you have... the following test is not exact but its close enough to see just how high your cya is to see how much you need to empty. (you will probably have to empty at least half of your pool, sorry, I know this is the last thing you want to read)

    extended CYA test, the 8th post down Extended Test Kit Directions
    basically your using half of the mix and multiply it by 2
    OK, it took me a while, but I finally got around to re-testing. New numbers:

    TC 0
    pH 7.1
    FC 0
    CC 0.5
    CH 600
    TA 170
    CYA 100 (extended test)

    I came back from vacation and there was no choline. I have added bleach to adjust. The CYA test was tested with the extended test, using half the amount of pool water plus tap water to make up the difference the reading was 50, therefore the true CYA is 100.

    The pool math calculator says I need to replace 60% of my water, so it sounds like that is my next step. Let me know if anyone has different advice.

    Pool: Outdoor, Plaster, 17K gallon, sand filter, choline sanitation, TF100 owner.

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