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Thread: Ph Swings, waterchanges etc!

  1. #16
    Registered Member BrendanJ23's Avatar
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    Default Re: Ph Swings, waterchanges etc!

    Well more co2 is present when lights are off because plants are not consuming it, but also releasing it, as are the fish.
    Then as it is consumed during the day, the PH rises. I have confirmed tonight that there is much less swing in PH with majority of plants removed from the tank. I will monitor this over the next few days for consistency.

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    Default Re: Ph Swings, waterchanges etc!

    Brendan, with CO2 users, there seems to be some debate regarding whether pH swings associated with fluctuating levels of CO2 are as harmful as lowered pH from other sources. I don't know why the nature of the conjugate base would have any impact on the effects of fluctuating pH. When I get my tanks set up I want a lot of plants but do not intend to test the effects of daily pH fluctuations. Regardless, pushing your kH up will lower the degree of pH fluctuation but the "fix" is to either reduce the number of plants, add CO2 during the day, or increase offgassing by increasing surface area either with more airstones, &/or adding a sump, &/or adding wet/dry filtration, &/or fluidized filter &/or spray bar for water return. My tank design includes all of these, I like redundancy.

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    Registered Member bluelagoon's Avatar
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    Default Re: Ph Swings, waterchanges etc!

    Plants will not flourish in that PH. Generally a PH of 5.5 - 6.5 but can go a bit higher. Usually not higher than 7.5 and some plants even have a difficult time taking up nutrients in that PH.

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    Default Re: Ph Swings, waterchanges etc!

    Quote Originally Posted by bluelagoon View Post
    Plants will not flourish in that PH. Generally a PH of 5.5 - 6.5 but can go a bit higher. Usually not higher than 7.5 and some plants even have a difficult time taking up nutrients in that PH.
    No argument in re aquarium plants in general but at the same time the 0.5 ph swing indicates that whatever type of plants he has, they are metabolically active suggesting good health. Brendan, purely for my curiosity, once you pulled the plants, did your ph trend closer to 8 or 7.5?

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    Registered Member BrendanJ23's Avatar
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    Default Re: Ph Swings, waterchanges etc!

    Quote Originally Posted by dspeers View Post
    No argument in re aquarium plants in general but at the same time the 0.5 ph swing indicates that whatever type of plants he has, they are metabolically active suggesting good health. Brendan, purely for my curiosity, once you pulled the plants, did your ph trend closer to 8 or 7.5?
    Hi Don,

    The tank only drops to about 7.9-8.0 at night, and peaks at about 8-8.1 during the day.

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    Registered Member BrendanJ23's Avatar
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    Default Re: Ph Swings, waterchanges etc!

    Quote Originally Posted by bluelagoon View Post
    Plants will not flourish in that PH. Generally a PH of 5.5 - 6.5 but can go a bit higher. Usually not higher than 7.5 and some plants even have a difficult time taking up nutrients in that PH.
    What’s the theory behind that Merv? I ask because I’ve always had plants grow and flourish in that PH range, I’m currently trimming about 3ft of growth off my vallisneria each month and I recently had my swords produce about 40 pups.

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    Default Re: Ph Swings, waterchanges etc!

    So basically your ph swing was due to an accumulation of CO2 when dark rather than exuberant photosynthesis raising your ph during the day. If you are satisfied with plant growth then the first problem can be addressed by increasing the effective water surface area. Had it been the second issue, would have either required adding CO2 during the day or keeping the plant biomass way down as you have already done. My understanding of the negative effects of alkaline water on plant growth is that several important nutrients, Iron, Calcium, etc. become less soluble as ph goes up causing deficiencies.

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    Registered Member BrendanJ23's Avatar
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    Default Re: Ph Swings, waterchanges etc!

    Quote Originally Posted by dspeers View Post
    So basically your ph swing was due to an accumulation of CO2 when dark rather than exuberant photosynthesis raising your ph during the day. If you are satisfied with plant growth then the first problem can be addressed by increasing the effective water surface area. Had it been the second issue, would have either required adding CO2 during the day or keeping the plant biomass way down as you have already done. My understanding of the negative effects of alkaline water on plant growth is that several important nutrients, Iron, Calcium, etc. become less soluble as ph goes up causing deficiencies.
    Ok, so increasing the effective surface water area means either a wider tank or sump? How does this affect it?

    My end goal is to be able to have plants, with minimal PH swing.

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    Default Re: Ph Swings, waterchanges etc!

    Quote Originally Posted by bluelagoon View Post
    Plants will not flourish in that PH. Generally a PH of 5.5 - 6.5 but can go a bit higher. Usually not higher than 7.5 and some plants even have a difficult time taking up nutrients in that PH.
    I kind of disagree with you here Merv as all of my tanks are planted my lowest ph being 6.8 and the highest being 7.2 I target feed on the initial startup of a tank but nothing afterwards I do not run co2 I run my lights 12hr a day and my plants are flourishing I think it comes down to fine tuning a tank, generally you can do a 30% water change with no adverse effects on ph

    Jeanne

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    Registered Member bluelagoon's Avatar
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    Default Re: Ph Swings, waterchanges etc!

    Quote Originally Posted by Sturiosoma View Post
    I kind of disagree with you here Merv as all of my tanks are planted my lowest ph being 6.8 and the highest being 7.2 I target feed on the initial startup of a tank but nothing afterwards I do not run co2 I run my lights 12hr a day and my plants are flourishing I think it comes down to fine tuning a tank, generally you can do a 30% water change with no adverse effects on ph

    Jeanne
    Plants will grow in that range. Not too high. My water is soft, is similar to yours. They would do much better between 5.5-6.5. but a few degrees on side or the other and most plants will do ok (5.0-7.5). But 8, I don't think you'll find many fresh water plants that can handle that much alkalinity. I see nutrient imbalance.
    Last edited by bluelagoon; 01-19-2020 at 10:32 AM.

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    Registered Member bluelagoon's Avatar
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    Default Re: Ph Swings, waterchanges etc!

    oops double post

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    Default Re: Ph Swings, waterchanges etc!

    Off-gassing the excess CO2 produced by the plants overnight first requires sufficient water circulation in the tank to avoid a concentration gradient, but with any reasonable flow (which you have with two canister returns) that should not happen. Your rate limiting step for removing CO2 is the total surface area between water and air. All aeration does is increase this interface by the size and number of the bubbles, same goes with either a fluidized biofilter https://www.youtube.com/watch?v=U9ovPRxMWk8 or a wet/dry chamber https://lovefishtank.com/wet-dry-sump-filter/ Since I am using both, I have a filter pad in the base of the box and use K-1 media in the fluidized filter. Adding a spraybar to the canister or sump filter return increases surface area, drilling a bunch of holes in the top of sump chamber separators to break up flow increases area. The fastest and easiest steps for you are to increase aeration with increased stones or bubble curtains, only need to run when lights off so aesthetics not an issue and add spraybars to your cannister returns. Reintroduce all the plants and see where you are at. If that still fails then would consider adding a sump. If you like your tank, that would be the last thing I change.

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