PH is unstable - should I do water changes or leave it? More info in post :)

donburi

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Hi all,

I have a 140L/37Gal tank that I have just finished fishless cycling. I am very very excited but I still can't get fish, because 1) I have very high nitrates (40ppm) and 2) my PH levels have been lowering since I did a 25% water change once the cycle finished (to lower nitrates).

So over the course of cycling my tank, the PH settled at about 6.4ppm which is fine for the fish I want (I have driftwood so it was initially higher as my tap water is 7.0ppm). I did the 25% water change 2 days ago, and after that the PH has been steadily declining. Yesterday it was 6.2, and today is was 6.0.

I also have a GH of 3 and a KH of 2, I know this is very low but I am wanting mainly tetra variety fish which would need a GH of under 10. I also know my nitrates are way too high right now, so I am going to continue to do water changes.

My questions are:

-If I don't use any buffers for my PH etc, will water changes alone be enough to keep the PH pretty steady after enough of them? I have been cycling the tank for over a month and only done one water change at the end so I'm assuming if I did weekly water changes then it would slowly rise again, is this true?

-Can I do water changes more than once a week, say every day or every other day, in order to lower the nitrates and get a higher PH or would that crash the cycle?

-Should I bother trying to raise my GH and KH using crushed coral or the likes or would it be better off to leave it?

So sorry for the long post but thank you in advance :) Just really want to nail this all down before introducing any fish!
 

YellowGuppy

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-If I don't use any buffers for my PH etc, will water changes alone be enough to keep the PH pretty steady after enough of them? I have been cycling the tank for over a month and only done one water change at the end so I'm assuming if I did weekly water changes then it would slowly rise again, is this true?
It stands to reason that if you remove a portion of low pH water and replace it with neutral pH water, your pH will get closer to 7.0. Remember that the pH scale is logarithmic, so don't expect a 50% water change to split the difference between your current pH and 7.0
-Can I do water changes more than once a week, say every day or every other day, in order to lower the nitrates and get a higher PH or would that crash the cycle?
You can do water changes as often as you'd like, or as large as you'd like. This is especially true for an aquarium that doesn't have any fish in it yet—there are no inhabitants to stress out by altering your water change schedule (even if doing so drastically). There's evidence that very little of the beneficial bacteria live in the water column items (most are adhered to surfaces) so it should have a negligible impact on your cycle.
-Should I bother trying to raise my GH and KH using crushed coral or the likes or would it be better off to leave it?
This one's a little more complicated, as GH/KH/pH are somewhat interlinked. Pick the parameter that matters most to you and work to stabilize that first. Having low pH and high GH/KH might get a little challenging. Fish are generally fairly adaptable to water conditions, so even if one parameter is a little outside of an ideal range, they'll likely grow accustomed to their surroundings.

Best of luck with the new tank!
 

Basil

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Is the GH of 3 and KH of 2 what your tank is now? Or is that your source water?
 

mattgirl

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Is the GH of 3 and KH of 2 what your tank is now? Or is that your source water?
And ^^this is the right question^^ :)

I have a 55 gallon tank full of vaious tetras. My PH pretty much stays at 7.2/7.4 I have very soft water so run crushed coral to keep it at that number. A stable number is much more important than a specific number.

All this to say, Tetras don't have to have a PH as low as you are trying to achieve. What is the PH straight from your tap?
 

Basil

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I keep wild caught Botia loaches at a ph of 7.4 and a GH of 6. It’s been a year and so far so good!
I think your ph of 7 from the tap is perfect.
Due to extreme well water (GH of 11, KH of 0 and a ph of about 5.5) I make my own RO/DI water. But even then.water chemistry had a mind of its own so I’ve settled with a consistent ph of 7.4 KH of 2, and GH of 6. If I try to raise the KH, my ph gets to about 8. So I also keep broken coral (what my good LFS recommended) in my filters to keep the KH from dropping and thus keeping the ph stable.

And ^^this is the right question^^ :)
I’m learning! Unfortunately, mostly through error rather than trial.
 
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donburi

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It stands to reason that if you remove a portion of low pH water and replace it with neutral pH water, your pH will get closer to 7.0. Remember that the pH scale is logarithmic, so don't expect a 50% water change to split the difference between your current pH and 7.0

You can do water changes as often as you'd like, or as large as you'd like. This is especially true for an aquarium that doesn't have any fish in it yet—there are no inhabitants to stress out by altering your water change schedule (even if doing so drastically). There's evidence that very little of the beneficial bacteria live in the water column items (most are adhered to surfaces) so it should have a negligible impact on your cycle.

This one's a little more complicated, as GH/KH/pH are somewhat interlinked. Pick the parameter that matters most to you and work to stabilize that first. Having low pH and high GH/KH might get a little challenging. Fish are generally fairly adaptable to water conditions, so even if one parameter is a little outside of an ideal range, they'll likely grow accustomed to their surroundings.

Best of luck with the new tank!
Thank you for this, that's really helpful. I was so worried if I did a lot of water changes then it would crash my cycle but that makes a lot of sense, and I do have a lot of nitrates so it needs to come down drastically.

I think in this case since the GH and KH would be okay so long as they're below 10, I'll focus on the PH since that's too low currently. I'll try changing the water and see how it goes :)

And ^^this is the right question^^ :)

I have a 55 gallon tank full of vaious tetras. My PH pretty much stays at 7.2/7.4 I have very soft water so run crushed coral to keep it at that number. A stable number is much more important than a specific number.

All this to say, Tetras don't have to have a PH as low as you are trying to achieve. What is the PH straight from your tap?
Okay so I tested my tap water and the KH is 3, GH is also 3 so not too much variance. I use seachem prime to condition my water in case that alters those stats a bit :)

That's also good to know about the PH. I guess I just want to stabilize it overall, since my kit (API Master test Kit) only reads to 6.0 so it could still be lowering without me knowing!!!

I will do a big water change today though and in the following days and see if I can get the PH to go up a little. I'm not too worried on the number so long as it's a constant since my tap water is only 7.0 so that would still be fine even if it got that high. Thank you!

I keep wild caught Botia loaches at a ph of 7.4 and a GH of 6. It’s been a year and so far so good!
I think your ph of 7 from the tap is perfect.
Due to extreme well water (GH of 11, KH of 0 and a ph of about 5.5) I make my own RO/DI water. But even then.water chemistry had a mind of its own so I’ve settled with a consistent ph of 7.4 KH of 2, and GH of 6. If I try to raise the KH, my ph gets to about 8. So I also keep broken coral (what my good LFS recommended) in my filters to keep the KH from dropping and thus keeping the ph stable.


I’m learning! Unfortunately, mostly through error rather than trial.
In regards to the crushed coral, do you just place a decent amount into a media bag and place it in or do you have to be quite specific on the measurements? If I could stabilize that way it might be good, I am also going to try just doing water changes to try and raise it a little from the tap water :)
 

mattgirl

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Okay so I tested my tap water and the KH is 3, GH is also 3 so not too much variance. I use seachem prime to condition my water in case that alters those stats a bit :)

That's also good to know about the PH. I guess I just want to stabilize it overall, since my kit (API Master test Kit) only reads to 6.0 so it could still be lowering without me knowing!!!

I will do a big water change today though and in the following days and see if I can get the PH to go up a little. I'm not too worried on the number so long as it's a constant since my tap water is only 7.0 so that would still be fine even if it got that high. Thank you!
Sounds like you have a good plan. In most cases it is best to work with what we have instead of trying to adjust things. Your tetras should be fine in water straight from your tap.

before adding crushed coral you may want to wait until you do a few water change to get the PH of the tank up to the PH of your source water. Keep an eye on the tank. If the PH remains stable at 7 CC may not be necessary.
 
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donburi

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Sounds like you have a good plan. In most cases it is best to work with what we have instead of trying to adjust things. Your tetras should be fine in water straight from your tap.

before adding crushed coral you may want to wait until you do a few water change to get the PH of the tank up to the PH of your source water. Keep an eye on the tank. If the PH remains stable at 7 CC may not be necessary.
Thank you so much for the advice :) I'll do the water changes over a few days and see how it goes!
 
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