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  1. #1
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    PH on the RISE ... WHY ???

    My current tank is 100 gallons net with fish only and base rock (no live rock at this time). I upgraded my lighting from 5 X 75 watt power saver household bulbs to 2 x 250 MH coralview 12 K bulbs 2 days ago. First issue was temp control and I have that dealt with. Tank is running between 78.9 and 80.7 from morning to late evening. HOWEVER the PH goes from 8.2 to 8.36 and beyound over the day??? I have some red slime on the go but not a big mess of it. I have changed NOTHING ELSE. I would have been expecting a drop in PH with the water being warmer but the reverse is happening. PH returns to 8.2 ish overnight and then climes over the day after the lights come on. This seems unusual ... any ideas??
    Rob

  2. #2
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    Maybe lack of O2? not sure.is a bit wierd though.

  3. #3
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    lack of O2 would drive PH down wouldn't it Johnny ??? I have made no effort to add additional O2 because I think that will compound the issue. It just hit 8. 37 and is bouncing off 8.38 ???
    Rob

  4. #4
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    Do you have any algae? One salty dog is right, lack of O2 and an increase in CO2 would drive the pH down. So, if there is something to consume the CO2 then the carbonic acid equilibrium will shift away from the acid therefore increasing the pH.

  5. #5
    NFR Mod Azonic's Avatar
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    Originally posted by smartin77
    So, if there is something to consume the CO2 then the carbonic acid equilibrium will shift away from the acid therefore increasing the pH.
    :wha?:

  6. #6
    ijo
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    I love these types of posts... so informative!!! I'll sit back and read this one

    Salty... could it be a faulty PH meter? have you tuned it lately?

    IJO

  7. #7
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    Okay, I may be totally wrong so somebody correct me if this is the case. However, if the tank has algae, then during the day time the algae will consume the CO2 during photosynthesis. CO2 is always in an equilibrium whereby is reacts with water to form carbonic acid. So, if there is alot of CO2 then there is more of it to react with water and more carbonic acid is formed hence driving the pH down (acidic). Now for the main point. If there is something to consume the CO2 like algae then less acid is produced and the pH will go back up. I now for sure that this is the case in the human body but I may be out to lunch for the tank. I give you permission to grill me if I am wrong... lol.

  8. #8
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    Ivan
    I still have a little of the red junk but as Iwas saying .... there really not too much in there.
    No I have not used the cal soluations yet but will check it out tomorrow and run a reg PH test. Redox however also falls over the day which makes more sence with the water warming up and holding less O2. It just seems to be that the PH is moving in the wrong direction ??
    Azonic ... the only thing in this tank is fish and a few shrimp Given the tanks size it is lightly stocked. There are NO missing fish ether.
    Lights have been out now for just over 1/2 hour and PH is already not bouncing off 3.8 .. It is now moving down and is bouncing off 3.6
    Rob

  9. #9
    Senior Member ALRHA's Avatar
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    normally when the lights are on, it is the algae that raises the pH. Do you have macro algae growing in a fuge or something? or it could just be the little algae you have in your tank raising the pH being that there isnt much competing to bring it back down.
    Albert
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  10. #10
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    ALRHA ... That woulds make sense if there was any algae in the tank but there is only fish (3 yellow tangs, 1 Hippo tang, 1 flame hawk, 7 chromes) and 4 shrimp... and all are accounted for. This tank is bare bones. There is no refuge, no skimmer. I did not expand on the set up because a new tank is in the works and I did not want to be moving stuff that was hardly settled in. The PH issue only started after I upgraded the lighting. On the first day the temp went to 83 because I did not vent the hood well enough but that has been corrected and the temp is now between 78 and 80 morning to night. The lights have been out now for just over 50 min and the PH is now bouncing off 8.35 so it is dropping now as it did yesterday. It just seems that the PH should be falling with the added heat?? I am confused
    Rob

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