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Thread: Ph Swings, waterchanges etc!

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    Default Ph Swings, waterchanges etc!

    Hi Everyone,

    Over the last couple of days I have been reading up on PH swings and I need another opinion and advice.

    My water in the aging barrel has no PH swing, after 24 hours of heavy aeration and heating. The water comes directly from the tap, through a series of sediment/carbon filters and then into the barrel. The ph of this water is around 8.2-8.4. I should mention that there is about 0.25 Ammonia in the tap water, and is always treated with prime.

    I have been watching my tank's PH, that swings from about 7.5 at night (lights dimmed or off) and climbs to about 8.0 during the day (lights on). I'm not sure what has changed but I don't recall the swing being this big in the past. I noticed my fish breathing heavy and a little bit stressed , so I started investigating. Currently I am doing 50% WC's daily, and have since day one.
    I'd like to continue the large water changes, however my thinking is that I will have to be strict in that I will have to do it during the day when the aging barrel PH and tank PH is closer.

    My other concern is the swing over night (as mentioned above), is this too large? Would removing plants be necessary in order to stabilize the PH or minimize the swing?

    Any insight would be great,

    Thanks,

    Brendan

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    Default Re: Ph Swings, waterchanges etc!

    With plants are you running co2 at all, and have you tried aging your water longer maybe 48hr to see if you get a swing

    Jeanne

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    Default Re: Ph Swings, waterchanges etc!

    Yeah that’s the plan with the current batch of water in the barrel. Nah no co2

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    Default Re: Ph Swings, waterchanges etc!

    Brendan have you checked you kH at all! The nitrogen cycle is an acidifying process, so if your kH is low or 0 the pH drop you are seeing could be related to your carbonates being consumed or depleted through the day and into the night resulting in the pH drop. If low/no kH is the problem you can add a bad of crushed coral or aragonite into your filter to mitigate the problem.
    On another note, I am flying into Brissy in March to spend a week my folks on Nth Straddie. Can't wait!

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    Default Re: Ph Swings, waterchanges etc!

    Quote Originally Posted by danotaylor View Post
    Brendan have you checked you kH at all! The nitrogen cycle is an acidifying process, so if your kH is low or 0 the pH drop you are seeing could be related to your carbonates being consumed or depleted through the day and into the night resulting in the pH drop. If low/no kH is the problem you can add a bad of crushed coral or aragonite into your filter to mitigate the problem.
    On another note, I am flying into Brissy in March to spend a week my folks on Nth Straddie. Can't wait!
    His PH increases with lights off though. At the beginning, mine had the opposite effect. It would decrease at night and increase during the day. However, there was only a .1 - .2 difference.

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    Default Re: Ph Swings, waterchanges etc!

    Mando I see your point, the pH swing is in the wrong direction for the acidifying process. Jeanne's suggestion then is what would test also, a 48 hours aging. Not sure why the pH change would take longer, but def worth checking.
    Either way, kH still has a direct connection to pH stability so I would test that as welt...
    Last edited by danotaylor; 01-13-2020 at 11:18 AM.

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    Default Re: Ph Swings, waterchanges etc!

    My read is that the Ph drops to ~ 7.5 in the dark and comes up during the day to ~8.0. Or is that only due to the daily water change? How much of a plant burden do you have in the tank? As well, how much agitation to break the surface tension? Surface area vs volume? If you have a high tank which I have, consider aggressive aeration overnight when plants and fish are both competing for O2 and producing CO2 which, since it is reversible next AM, I would blame for the Ph drop rather than the production of nitrates and nitric acid. Regardless, the lower your Carbonate hardness the wider the ph swings so I agree, test and fix.

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    Default Re: Ph Swings, waterchanges etc!

    Quote Originally Posted by danotaylor View Post
    Mando I see your point, the pH swing is in the wrong direction for the acidifying process. Jeanne's suggestion then is what would test also, a 48 hours aging. Not sure why the pH change would take longer, but def worth checking.
    Either way, kH still has a direct connection to pH stability so I would test that as welt...
    I read it wrong anyways! it does drop.

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    Default Re: Ph Swings, waterchanges etc!

    Quote Originally Posted by danotaylor View Post
    Brendan have you checked you kH at all! The nitrogen cycle is an acidifying process, so if your kH is low or 0 the pH drop you are seeing could be related to your carbonates being consumed or depleted through the day and into the night resulting in the pH drop. If low/no kH is the problem you can add a bad of crushed coral or aragonite into your filter to mitigate the problem.
    On another note, I am flying into Brissy in March to spend a week my folks on Nth Straddie. Can't wait!
    Hey mate yeah KH is 5-6. I was reading that ph will drop at night because the plants are no longer consuming the co2, and it rises during the day because the plants are removing the co2 from the water. I do have crushed coral on me that I can try. Just wanted to pick some brains first before I go doing anything.

    Yeah mate if youíre around Iíve got cold beer in the fridge and we can talk discus!

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    Default Re: Ph Swings, waterchanges etc!

    Quote Originally Posted by dspeers View Post
    My read is that the Ph drops to ~ 7.5 in the dark and comes up during the day to ~8.0. Or is that only due to the daily water change? How much of a plant burden do you have in the tank? As well, how much agitation to break the surface tension? Surface area vs volume? If you have a high tank which I have, consider aggressive aeration overnight when plants and fish are both competing for O2 and producing CO2 which, since it is reversible next AM, I would blame for the Ph drop rather than the production of nitrates and nitric acid. Regardless, the lower your Carbonate hardness the wider the ph swings so I agree, test and fix.
    Tank is 6ftx2x2, two fx6’s outlets for surface agitation, and 3 air stones throughout the tank, running 24/7.

    I’ll check the PH in the aging barrel this afternoon to see if it’s shifted after 48 hours.
    I’ll also put a fist sized bag of crushed coral in one of the filters and report back with my findings. Sound ok?

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    Default Re: Ph Swings, waterchanges etc!

    Results this afternoon (3pm):

    Ph -
    Aging barrel (aged 48 hours) 8.5

    Water straight from filter that fills aging barrel 7.5

    Straight tap water, no filtering or aging etc 8.0

    Fish tank 7.9

    No crushed coral has been added yet, will do shortly

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    Default Re: Ph Swings, waterchanges etc!

    maybe some rock, sand make ph up. How long aquarium is started?

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    Default Re: Ph Swings, waterchanges etc!

    Kh is actually reasonable, you can bring it up to ~8 if you want but you already have adequate buffer. Hope you have a ton of plants, otherwise I am at a loss. Plants in the dark not only do not absorb CO2, they produce it, and in addition compete with the fish for O2, which sort of would explain the heavy breathing you observe (I assume first thing in the AM). But with your 3 airstones going would not expect your fish to be symptomatically hypoxic due to plants which they act like they are. Despite your 3 air stones you may actually have to increase aeration when dark, or reduce plants. My plan is to put bubble curtain walls along both sides of the my tanks to run at night to minimize this potential problem as I love planted tanks, but I have high tanks. You are always going to have some variance of ph, but I am surprised it reaches 0.5 as CO2 dissipates rapidly from liquid into atmosphere. How tightly sealed is your tank top? What kind of filter do you run that would drop your tap ph from 8 to 7.5? That it goes up to 8.5 is due to offgassing CO2. Also just to be clear, your ph recovers in the morning before your water change, or is it the water change that raises the ph from the night before?

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    Default Re: Ph Swings, waterchanges etc!

    Quote Originally Posted by dspeers View Post
    Kh is actually reasonable, you can bring it up to ~8 if you want but you already have adequate buffer. Hope you have a ton of plants, otherwise I am at a loss. Plants in the dark not only do not absorb CO2, they produce it, and in addition compete with the fish for O2, which sort of would explain the heavy breathing you observe (I assume first thing in the AM). But with your 3 airstones going would not expect your fish to be symptomatically hypoxic due to plants which they act like they are. Despite your 3 air stones you may actually have to increase aeration when dark, or reduce plants. My plan is to put bubble curtain walls along both sides of the my tanks to run at night to minimize this potential problem as I love planted tanks, but I have high tanks. You are always going to have some variance of ph, but I am surprised it reaches 0.5 as CO2 dissipates rapidly from liquid into atmosphere. How tightly sealed is your tank top? What kind of filter do you run that would drop your tap ph from 8 to 7.5? That it goes up to 8.5 is due to offgassing CO2. Also just to be clear, your ph recovers in the morning before your water change, or is it the water change that raises the ph from the night before?
    Hi Don,

    My top of tank has lids, but plenty of gaps to allow for gas exchange etc. The filter is just a carbon/sediment cartridge filter. No the Ph seems to follow the pattern of decrease and increase regardless of WC's.

    I've been testing and documenting the water and doing some experiments this week.

    I added a handful sized bag of crushed coral to the filter this week, can't say I have noticed a difference. I may add more in future, just wanting to make small changes over time to minimise stress. I removed half of the potted plants on Thursday, with no measurable difference of Ph swing pattern. I measured the PH daily at 3pm before any waterchange and it was at 8.1. I have also dropped to a 30% WC of unaged water, daily while the lights are still on. This ensures the water I am changing and adding is the same PH. Today (friday) I have removed the remainder of the potted plants, leaving only a few small java ferns, anubias and mosses/algae that is on the driftwood. I will test the PH tonight and monitor for the next few days to see if the PH stabilizes at all.

    I should also note for comparison, that my outside turtle pond (about 1000L) has a consistent Ph of around 8.2, and TDS of around 800. There is about 30kg of crushed coral in the pond, with bugger all plants as they eat it. This probably gets two large water changes per month, sometimes not even that. Its never seen a siphon, and doesn't get any pre-filtered water. (I just dose prime).

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    Default Re: Ph Swings, waterchanges etc!

    One thing that confuses me here is that your ph drops with lights off generally in a planted tank or if your running co2 your ph would go up, have you tried running your lights longer say 12hr a day so that more co2 is consumed during the day which would in turn lessen the swing

    Jeanne

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