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Need Some Help Understanding Co2 Via Kh/ph

Discussion in 'CO2 Enrichment' started by Joseph Wong, Jun 13, 2019.

  1. Joseph Wong

    Joseph Wong New Member

    Jun 13, 2019
    Likes Received:
    Local Time:
    11:58 AM
    Hi guys

    New hobbyist here.
    Great forum here with plenty to learn.

    Just have some questions with co2 specially for my tank that can I get some help with please?

    Tank wise
    Its a 3ft tank, of about 59gallons.
    Using a 1500l/hr filter with jbl co2 inline atomizer going through a chiller as well.
    Filter inlet wise is a 2 in one, a surface skimmer at the top and normal inflow at the bottom, so I'm wondering is this affecting my co2 gaseous exchange?

    This are the values I have

    Just moments before co2 turns on
    PH 7
    Kh 4

    8hrs into co2 (coming to the end of photo period)
    PH 6.4
    Kh 5

    I have read that I should aim for a 1degree drop in pH to sort of have around 30 ppm of co2.
    But as my kh have shifted by 1 degree, should I be still aiming for pH 6 for that 1 degree drop?
    Currently my bps feels extreme already at 5 or 6 bps so will like to know more before gassing further for that 1 ph drop. I know that bps is inaccurate, but for someone new, it's a reference point that I'm looking at still.
    I'm also using a drop checker to help with my co2 levels before I understand better on this kh pH things.
    Pre co2 is blue.
    End of photo period is yellowish green.

    10am (co2 goes on)
    12.30pm ( lights goes on) (photo period start)
    7.15pm (co2 goes off)
    7.30pm (lights goes off)
    8pm (air pump kicks in)
    10am (air pump offs)

    To sum up.
    1) based on my before and after pH/kh values, how do I count how much co2 do I have nearing the end of the photo period?

    2)should I be using a seperate dedicated skimmer and get a normal inlet as probably the filter surface skimmer is affecting how much co2 I'm injecting in, so even though its at 5/6bps, my co2 still feels lacking?

    3)does the airpump gives me any benefits for the plants/fish at night if i already got a surface skimmer?

    thanks guys
  2. Robb

    Robb New Member

    Apr 1, 2019
    Likes Received:
    Local Time:
    10:58 PM
    Hi Joseph,
    Do you have some surface agitation as well as the skimming going on? I think both are necessary for good gas exchange and stabilizing CO2 and O2 levels. The skimmer removes organics that can build up on the water surface impeding gas exchange.

    Are the pH, kH values you measured consistent day by day or was that just one day’s reading? The values you measured near the end of your photoperiod actually put your CO2 levels well above 30 ppm. According to one table, you’re approaching 60 ppm! Levels exceeding 30 ppm are okay for fish and shrimp as long as oxygen levels are kept high enough. This is where good surface agitation and good flow throughout the aquarium become so important.

    In my opinion I think you can reduce your bubble rate of CO2. Levels above 30 ppm don’t really benefit the plants that much and so I think you’re wasting CO2. Maybe shoot for a bubble rate that has your pH settling out between 6.6-6.7.

    Pay attention to your drop checker. Is it green before the lights come on? You want have those CO2 levels high enough by the time the lights come on so there’s plenty of it around for the plants to utilize when the lights first come on. Photosynthetic activity of your plants is the highest in the first part of the photoperiod. Adjust your bubble rate accordingly to achieve a pH that gets you to the ppm CO2 you want. Your drop checker should also be green or at least noticeably changing in color.

    I hope all this information helps you! There are others much more experienced than I on this forum so hopefully they’ll chime in as well. Be patient, make a change, and wait for the result. With some tweaking and a bit of time, you’ll get it right and your plants will thank you with lots of vigorous growth! Best of luck.

    Andy Taylor likes this.

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