Why is my pH so high???

Discussion in 'Water Chemistry' started by Fran, 9 Jun 2013.

  1. Fran

    Fran Member

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    Hi all, further to a recent thread I started on here, I am now using 100% tap water which is pH 6.8 and TDS 450. However, my tank water is pH 8.1 in the morning and 7.8 in the evening when the CO2 is on. Now using up to 6 bps and still can't get a green drop checker or get the pH to drop. Have some dragon stone in the tank and unipac fiji sand which is supposed to be inert. So whats raising my pH. Any help appreciated.
     
  2. Alastair

    Alastair Member

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    Doesnt dragon Stone leach out calcium etc slowly? This may have an impact on your ph

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  3. Yo-han

    Yo-han Member

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    My guess would be high KH as well.
     
  4. Fran

    Fran Member

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    Hi, apologies but I was a bit premature about my drop checker. Its now lime green but tank pH is still 7.8. pH was stable before when I was using RO water.
     
  5. Kogre

    Kogre Member

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    Large water changes would be problematic if there's that much of a difference.
     
  6. sciencefiction

    sciencefiction Member

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    Have you tested your tap water once it sits for 24 hours in an open glass? Tap water contains CO2 so once it settles/is aerated, the Ph goes back up to what it would be on a contstant basis. My tap water Ph is 6.6, tank settles at 7.4.
    Your TDS is high, which suggests your tap water is hard, so no surprise the Ph won't go down as probably you've got high Kh. The GH is probably high too.

    Dragon stone can also add to that but as far as I am aware it's very minimal.
     
    dw1305, foxfish and justissaayman like this.
  7. justissaayman

    justissaayman Member

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    My tap is 7.2 out of the tap and 8.2 after 24 hours.

    Tds will also change with temperature and co2 will affect ph slightly as well.

    Sent from my Nexus 7 using Tapatalk HD
     
  8. sciencefiction

    sciencefiction Member

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    TDS changes with temperature, but if you've got a good TDS stick they are made to compensate for that so it doesn't matter what temp the water you are testing is.
     
  9. dw1305

    dw1305 Expert

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    Hi all,
    It does, but not by very much.

    Graph1.jpg
    That is a bit strange, the only explanation for the initial low pH is dissolved CO2 in the pressurised tap supply. The drop checker is just a pH indicator. I'm sure the other respondents are correct and it would suggest that you have a lot more than 4dKH carbonate hardness in your tap water (450 TDS would also suggest you have a lot of salts, of which the most likely is CaCO3).

    Personally I think your best bet is to just ignore pH.

    cheers Darrel
     
  10. Andy Thurston

    Andy Thurston Forum Moderator Staff Member

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    Id be tempted to look at tds and ph pen calibration too, wrong readings maybe an explaination for strange water chemistry
    My ph pen read +0.5 when i first got it
     
  11. Fran

    Fran Member

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    Hi all and thanks for the help. Im happy that the DC is green at the moment so I'm not too worried. Fish seem fine too. I suppose pH of 8.1 is a bit extreme so I have ordered some pH calibration fluid for my tester. As Justissaayman states above there can be a big difference in tap water pH after it has been left to settle. I have now found that my tap pH is 7.9 after I let it settle in a jug for 24 hours. Which now reads the same as the tank water with the co2 on. So I now reckon the pH pen is in need of calibration.
     
  12. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

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    I agree with Darrel that you should completely ignore the pH as well as conductivity. Neither your fish nor your plants really care. If you want to worry about something then worry about getting your CO2 right and about keeping the tank clean. A pH of 8.1 doesn't really mean anything in this case.

    Cheers,
     

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