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Thread: Alum (Aluminum Sulfate) effects on pool chemistry

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    smeestu's Avatar
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    Alum (Aluminum Sulfate) effects on pool chemistry

    After reading a lot on here it would seem that using alum as a floc is generally frowned upon .
    Its something that a few pool owners i now here in N/E Thailand (as recomended by there pool builder)
    do on a regular basis maybe once a month for some of them
    i have used it before with good results for clearing my cloudy pool within a day or so .
    What i noticed before was it drops the PH when you use it
    was wondering what other effects it had on the pool chemistry balance.
    Hopefully wont be using it any more as im going to use the method described on TFP
    it was more out of interest than anything else and why people seem to be against it .
    I now understand if the pool is balanced properly should be no need for it .
    Home built Concrete pool tiled 100% 6M X 12M 1.1-1.6 m deep 93,000 litres 24,500 US gallons
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    Re: Alum (Aluminum Sulfate) effects on pool chemistry

    Coagulants, clarifiers, and flocculants are not needed in a properly chlorinated residential pool. Neither are enzymes, "shock", ozone, UV, metal ions, or other products. People use such products most commonly because they use Trichlor pucks/tabs that build up CYA in the pool and that lowers the active chlorine level that is proportional to the FC/CYA ratio. The lower active chlorine level allows algae to grow faster than chlorine can kill it and that often makes the water dull/cloudy (depending on algae species) before a full-fledged algae bloom appears. Also, the lower active chlorine level more slowly oxidizes bather waste so it may stay in the water longer and also cause some cloudiness.

    The reason that alum products drop the pH is that they form aluminum hydroxide floc so the removal of the hydroxide lowers the pH.

    Other than creating a precipitate that gets caught in the filter (or settles to the bottom of the pool, depending on how much you use), there shouldn't be other side effects with it. You mostly end up filtering it out though if the pool is fairly clean that can take some time.
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    Re: Alum (Aluminum Sulfate) effects on pool chemistry

    Since you've used it before and you mentioned "monthly" it sounds like the pool getting cloudy is more than a one time occurrence. Any idea what might be causing it ?? Might be something simple and stopping the cause puts you way ahead of having to filter it out after.
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    Re: Alum (Aluminum Sulfate) effects on pool chemistry

    I would hazard a guess that this monthly cloudiness is from high CYA and inappropriate amount of FC.

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    Re: Alum (Aluminum Sulfate) effects on pool chemistry

    Hi thanks for your replys i was uneducated with the FC/CYA problems before and yes i did use alum on several ocasions (i personally didnt use it every month) but there is a guy who has built 5-6 pools in a 60 mile radius from where i live and has told the owners to use trichlor and alum i personally know 3 of them and they all have the same problem that i had green/clouding and the last time it happened i put 2kg of trichlor in that should of riased the FC up around 20 and it didnt seem to do anything thats what got me thinking the chlorine doesnt seem to be doing its job . So on the internet i go and i find here ,after plenty of reading i understand my problem (i think) too much CYA from the Trichlor so i phone a friend a few hours away that has a comerical pool tester and sent him some samples of water one from the pool one from the well water i use . It came back that the CYA was 146 so it seemed that i was on the right track which would of put normal FC levels at 11-18 and a shock level of 57 .

    So i decieded to empty the pool by poolmath i needed to ditch 65% so i emptied it gave it a good scrub and started to fill it again .The thing is the well water isnt the best so i put a small cartrige filter on it that kept the worse out after a few days im getting close to full (much quicker then the first time took 2 weeks ) as soon as i could i ran the pump//filter whilst filling also bought some bleech from the local shop (ive ordered 200 litres) it had started to go green striaght away now i have the chlorine levels over 5 the water is more brown than green and theres a lot of what i guess is dead algae on the floor which ive been vacuming the pump/filter has been on for 24hours (hasnt needed to backwash yet ?) anyways the question was really more about the Alum if it didnt do any harm it might of been worth doing it once when its 100% full rather than running the pump for days and filtering/vacuming it out . Ive ordered a Palintest test kit SP315C which im waiting for delivery and will not be using trichlor (unless to raise the CYA level ) ill be sticking with bleech and will keep a eye on the FC/CC/PH/CYA/TA/CH and hopefully have a nice clean balanced pool ,
    Home built Concrete pool tiled 100% 6M X 12M 1.1-1.6 m deep 93,000 litres 24,500 US gallons
    Emaux SB15 1.5hp pump ,Emaux v700B Sand Filter with Zealbrite
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    Alum (Aluminum Sulfate) effects on pool chemistry

    Did you look to see if you can get the SP 300 kit too. That is the FAS/DPD chlorine test which can measure high levels of chlorine. I think the kit your getting can only measure FC of up to 5. It would be a good idea to have the SP 300 kit also in case you had an algae problem and had to SLAM the pool. 😎
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    Re: Alum (Aluminum Sulfate) effects on pool chemistry

    Thanks for the Reply yes i did ask them he didnt have any in stock but can order it said there wasnt much call for it in the UK .I needed something striaght away so i got him to ship the basic kit that does FC/CC/CYA/TA/CH out to Thailand from the UK ive got family coming over xmas time so ill get them to bring one out then i can see that im going to need one as/when/if i need to slam to hold the high FC levels over time he did say i could dilute the the test by 50% which would in effect double the reading (goes up to FC 6) so up to 12 FC but i think in the long run a FSD/DPD kiy would be more usefull as well .I was wondering about regents/tablets and a rough guess on how much i need to buy i know the tablets have a long shelf life but most regents seem to be about 12 months .Having to ship everything 6000 miles is a pain
    Home built Concrete pool tiled 100% 6M X 12M 1.1-1.6 m deep 93,000 litres 24,500 US gallons
    Emaux SB15 1.5hp pump ,Emaux v700B Sand Filter with Zealbrite
    Emaux SSC50-T 45g/hr swg ,Jacuzzi chlorine Tablet Feeder

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    Re: Alum (Aluminum Sulfate) effects on pool chemistry

    Just as a follow up i didnt put alum in to clear it just kept the pump running and vacuming twice a day keeping FC up at 10 ( by diluting the basic swimline test kit buy half and using pool math calculator and now i have a nice clear pool , picked up 200litres of 10% liquid chlorine so lets see how it goes from here just waiting for my main test kit now
    Home built Concrete pool tiled 100% 6M X 12M 1.1-1.6 m deep 93,000 litres 24,500 US gallons
    Emaux SB15 1.5hp pump ,Emaux v700B Sand Filter with Zealbrite
    Emaux SSC50-T 45g/hr swg ,Jacuzzi chlorine Tablet Feeder

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    Re: Alum (Aluminum Sulfate) effects on pool chemistry

    Good job!
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    smeestu's Avatar
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    Re: Alum (Aluminum Sulfate) effects on pool chemistry

    Thanks its a learning curve for me and i had to stick with it even if i got a bit impatient but its clear staying clear so now to balance the rest of the levels 100% and see how it goes from there .Which should get easier as my test kit arived today
    Home built Concrete pool tiled 100% 6M X 12M 1.1-1.6 m deep 93,000 litres 24,500 US gallons
    Emaux SB15 1.5hp pump ,Emaux v700B Sand Filter with Zealbrite
    Emaux SSC50-T 45g/hr swg ,Jacuzzi chlorine Tablet Feeder

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    Re: Alum (Aluminum Sulfate) effects on pool chemistry

    SWEET! I can't wait to see what your levels are! Let us know soon!

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    smeestu's Avatar
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    Re: Alum (Aluminum Sulfate) effects on pool chemistry

    Just done the levels this afternoon FC 6 PH 7.6 TA 180 CH 140 CYA is somewhere between 10-20 ill have to get used to the black dot .
    Havent done a CC test yet either havent got the instructions how to do it with the kit just emailed the seller to make sure i do it right
    ive been using some trichlor granules i had left over to bring the CYA up whilst watching the FC carefully as CYA is low and theres lots of sun here . ill have to raise CH as well is it worth doing anything with the TA as its on the high side the pool is nice and clear . i must say the tests match the colours 100% not like the cheap **** i used before and the TA and CH test when the colour changes its really clear to see so over all im really happy with the kit
    Home built Concrete pool tiled 100% 6M X 12M 1.1-1.6 m deep 93,000 litres 24,500 US gallons
    Emaux SB15 1.5hp pump ,Emaux v700B Sand Filter with Zealbrite
    Emaux SSC50-T 45g/hr swg ,Jacuzzi chlorine Tablet Feeder

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