Confused with effects of aeration on pH & Alkaline Buffer/Acid Buffer

Can someone with some chemistry background give me a hand?

My water out of the tap has a pH of 6.8-7 and <1 deg of GH and KH. If I aerate it with a water stone or let it sit out 24h, the pH comes down to 6,6-6.8.

In order to combat pH swings I am raising buffering capacity/adding KH with Seachem Alkaline Buffer and Acid Buffer. In a 5 gallon bucket of water, I can add alkaline buffer to bring the KH up to 6 deg and then use acid buffer to drop the pH from 8.0 back down to 7.0. However, the puzzling part is that if I leave an air stone in the adjusted water for an hour, the pH shoots back up to 8.2. What is going on here?

 

Not sure what’s going on there but my best advice is to stop tinkering with the ph levels. It’s much harder to chase a pH value you want than to just use what you have. I’ve heard lots of people say their pH from tap drops after 24 hrs sitting out, it’s something in how they treat your water. These people just leave the water sitting out over night before a water change so the pH matches the tank.

 

Thanks for the input. Really my goal was to just raise KH to keep my pH from dropping between weekly water changes. I'll run the aquarium at 8.0 if I have to. I might shoot an email to Seachem and see what they have to say.

 

What is your source water? Municipal water, well? And does it go through an RO/DI system? That’s strange to have such a low KH and GH.
I remineralize RO/DI water with Seachem products but the ph goes up after aerating it. Which I guess makes sense as I’m guessing the hydrogen atoms are bound up when oxygen is introduced. But I’m not a chemist!
Let us know what Seachem says if you talk to them.

 

My tap comes out at 0 kh, it’s not unheard of to have 0 and 0 in tap.

If all you want to do is raise the kh to maintain a ph that won’t fluctuate, add some crushed coral to the hob filter.

 

Thanks Basil, I will report back from Seachem. The water is municipal. I have tested 2-3 times to make sure I didn't have an error in testing. I also asked the guy at the LFS and he confirmed that our water here (Greenville, SC) is very soft. Basically free RO/DI.

 

Thanks Basil, I will report back from Seachem. The water is municipal. I have tested 2-3 times to make sure I didn't have an error in testing. I also asked the guy at the LFS and he confirmed that our water here (Greenville, SC) is very soft. Basically free RO/DI.

I guess that’s easier to deal with than my well water which has 0 KH, 11 GH, 5.4 ph, and at times up to 40 ppm of nitrates. Thus the RO/DI!

 

After snooping around the Seachem forum, I think I found the answer to my question. When you use both alkaline and acid buffers, the reaction off-gasses CO2 slowly using up the acid buffer (pH creeps up). The more surface agitation you have, the quicker the acid buffer gets used up. I wish Seachem explained this a little better on their packaging.

How do most people remineralize RO/DI water, specifically raise KH, without jacking up their pH?

 

After much experimenting in 5 g buckets, the best I could achieve was GH of 6-7, KH of 2, and ph of 7.4.
I was aiming for a higher KH and ph of about 7 but this is working.
Every once in a while, one tank will drop to maybe a 7.2 ph but no lower.
I also have to do weekly water changes although I have tested and seem to be able to go about 10 days before too much of a drop.
I’ve also copied this from member Chanyi who just uses these chemicals to remineralize. I’m drawn more to doing this but need to get some more buckets to experiment again.

0.386 Grams CaSO4 - 30ppm Ca, 4.2 degrees general hardness (GH)

0.384 Grams MgSO4 - 10ppm Mg, 2.3 degrees general hardness (GH)

0.135 Grams KHCO3 - 14ppm K, 1.0 degrees carbonate hardness (KH)

This should give a ph of 7.0

 

2.5 gallon tank, heated
Tap water pH is 9.4, aerated for 3 hours, it's 7.9
Undergravel filter which makes adding crushed coral a challenge
Cycled, KH 1.5-2, GH 4-5, Ammonia 0, Nitrites, 0, Nitrates 20

I'm having wide pH swings. Last night it was 7 and woke up this morning to 6.4.

I have RO water available. I wonder how I can use Seachem Equilibrium, Alkaline & Acid buffer to hold 7-7.5.

I know some replies will recommend a larger tank...that's not going to happen short-term. I have a betta, mystery snail, and three plants. Everyone seems happy and I want to keep it that way. I'm leaving for a week next month and won't be here to babysit the water parameters so closely, so I need to find stability.

 

2.5 gallon tank
Tap water pH is 9.4, aerated for 3 hours, it's 7.9
Undergravel filter which makes adding crushed coral a challenge

I'm having wide pH swings. Last night it was 7 and woke up this morning to 6.4.

I have RO water available. I wonder how I can use Seachem Equilibrium, Alkaline & Acid buffer to hold 7-7.5.

I know some replies will recommend a larger tank...that's not going to happen short-term. I have a betta, mystery snail, and three plants. Everyone seems happy and I want to keep it that way. I'm leaving for a week next month and won't be here to babysit the water parameters so closely, so I need to find stability.

Im curious as to what your tap water PH is after 24 hours.
Your tap water PH drops as it sits out because its equalizing with the carbon dioxide levels in the atmosphere. As carbon dioxide enters the water the PH will drop. You will see this happen after a few hours.

But......

After about 24ish hours all of the chlorine in your water will evaporate and that raises your PH back up a bit.

9.4 to 7.9 after a few hours means that your tap water is fairly hard....(im jealous).

7 to 6.4 is not really a wide swing....its normal for your PH to move around a bit over the course of a day.

Im betting that you don't really need to be adding crushed coral.

Have you tested your GH/KH?

since it's only a 2.5 gallon tank, leaving some water out to gas off overnight before a water change shouldn't be very difficult.

I'd be curious to see how that alone would do.

 

Im curious as to what your tap water PH is after 24 hours.
Your tap water PH drops as it sits out because its equalizing with the carbon dioxide levels in the atmosphere. As carbon dioxide enters the water the PH will drop. You will see this happen after a few hours.

But......

After about 24ish hours all of the chlorine in your water will evaporate and that raises your PH back up a bit.

9.4 to 7.9 after a few hours means that your tap water is fairly hard....(im jealous).

7 to 6.4 is not really a wide swing....its normal for your PH to move around a bit over the course of a day.

Im betting that you don't really need to be adding crushed coral.

Have you tested your GH/KH?

since it's only a 2.5 gallon tank, leaving some water out to gas off overnight before a water change shouldn't be very difficult.

I'd be curious to see how that alone would do.

KH is 1.5-2, GH is 4-5. The testing colors look like the want to change a 1 and 4 respectively, that's why I assign a range.

After 24 hours, without aeration, the water ph drops to 7.8...the same as if I aerate it for a few hours. My water is municipal sourced from lake erie, which is 8-8.2 pH. We have a new water treatment facility that's supposed to protect us from algae blooms (microcystin).

I'm thinking about just using my RO water and adding seachem products (equilibrium and buffer) to get it where it needs to be. When I first established this tank I wasn't checking pH. When I eventually did, I found the pH was 5.8, while using RO that was never re-mineralized. I lost a Betta... I was doing much larger water changes once per week. Now I'm changing 5-10% per day without large water changes.

I realize crushed coral is a better/lower maintenance option, but I'd like to just treat my water going in, monitor it, and keep a steady pH.

 

KH is 1.5-2, GH is 4-5. The testing colors look like the want to change a 1 and 4 respectively, that's why I assign a range.

After 24 hours, without aeration, the water ph drops to 7.8...the same as if I aerate it for a few hours. My water is municipal sourced from lake erie, which is 8-8.2 pH. We have a new water treatment facility that's supposed to protect us from algae blooms (microcystin).

I'm thinking about just using my RO water and adding seachem products (equilibrium and buffer) to get it where it needs to be. When I first established this tank I wasn't checking pH. When I eventually did, I found the pH was 5.8, while using RO that was never re-mineralized. I lost a Betta... I was doing much larger water changes once per week. Now I'm changing 5-10% per day without large water changes.

I realize crushed coral is a better/lower maintenance option, but I'd like to just treat my water going in, monitor it, and keep a steady pH.

calcium carbonate is your answer though, calcium will raise you GH, carbonate will raise you KH. and keep them stable. getting those two parameters up will normalize and stabilize your pH and allow for amendments to pH to "stick", by getting them up and in balance, you might not have to amend the pH at all except to let the water sit before adding it.

you can play with the chemicals to raise or lower pH but the issue is the lower KH ( it's under 2, it should be 4-8 dKH) your GH is 4-5, (it should be between 4 to 8, so this is ok, maybe a little low) the problem is the KH.

now, MgSO4 Magnesium sulfate (epsom salt) will raise the GH without raising the KH, as will CaSO4 (calcium sulfate).

KHCO3 Potassium Bicarbonate (potassium hydrogen carbonate), or K2CO3 Potassium Carbonate (Potassium Sodium carbonate technically) will raise KH and not touch GH.

NaHCO₃. (baking soda) is Sodium bicarbonate, it's a Sodium Hydrogen Carbonate. it will add sodium to the tank, but most all of the buffers do that aren't coral shell or rock in crushed form. .

For this reasoning, for ONLY raising KH, I'd use KHCO3 Potassium Bicarbonate to amend the water. you will have some excess potassium, I'd suggest planting to use that up. if the excess potassium ends up feeding algae, you could just try the baking soda, and deal with the excess sodium which won't cause algae.

this is why the crushed coral (calcium carbonate) is the better option it hits both GH and KH equally, and maintains them in the safe range for the tank and the pH controls it's release, and as the water shifts alkaline or acid but even the slightest, it buffers that to keep it steady and not shift.

if you insist on amending the water instead. it's going to be trial an error and doing it in buckets that sit for 24 hours before amending, and measures noted so you can reproduce the results when you settle on a dosing that works.
the "buffers in a bottle" will have you shifting the pH acid or alkaline and one cancelling the other out and you not hitting what you want to be because your KH (carbonates) isn't high enough to make them stick,

Like Seachem Alklaine Buffer, it's a proprietary mixture of salts, no potassium. this raises pH and creates KH (doseage if 1 teaspoon per 20g raises dKH by 2.8........

The Seachem Acid Buffer is no magnesium, and still a proprietary mixture of salts. this lowers pH and Converts carbonate alkalinity (KH) into available CO2.

so both products are sodium forms of carbonate (easier to tell with the Alkaline Buffer than the acid buffer) . they will raise or lower pH and "buffer it" to where you want it, but theres' nothing to KEEP it where you want it. you'll wind up pushing your dKH up, and the pH with it, then using the Acid buffer to take the pH back down, and the KH with it, and then back up again. it's even less stable of a method because it's amending the pH THROUGH playing with the KH instead of amending the KH to get a stable pH.

And all said and done, a stable pH is what you need, a little high, a little low the fish can and will acclimate to it and it will be fine. it's the wild swings that are damaging to the fish, the instability of the pH that kills.them. raising KH will get you where you want to be, raising KH and GH together and in balance with each other will keep you where you want to be for pH. and putting in a half pound of crushed coral once a year or so in the substrate would get it done.

up to you on how to proceed.

 

calcium carbonate is your answer though, calcium will raise you GH, carbonate will raise you KH. and keep them stable. getting those two parameters up will normalize and stabilize your pH and allow for amendments to pH to "stick", by getting them up and in balance, you might not have to amend the pH at all except to let the water sit before adding it.

you can play with the chemicals to raise or lower pH but the issue is the lower KH ( it's under 2, it should be 4-8 dKH) your GH is 4-5, (it should be between 4 to 8, so this is ok, maybe a little low) the problem is the KH.

now, MgSO4 Magnesium sulfate (epsom salt) will raise the GH without raising the KH, as will CaSO4 (calcium sulfate).

KHCO3 Potassium Bicarbonate (potassium hydrogen carbonate), or K2CO3 Potassium Carbonate (Potassium Sodium carbonate technically) will raise KH and not touch GH.

NaHCO₃. (baking soda) is Sodium bicarbonate, it's a Sodium Hydrogen Carbonate. it will add sodium to the tank, but most all of the buffers do that aren't coral shell or rock in crushed form. .

For this reasoning, for ONLY raising KH, I'd use KHCO3 Potassium Bicarbonate to amend the water. you will have some excess potassium, I'd suggest planting to use that up. if the excess potassium ends up feeding algae, you could just try the baking soda, and deal with the excess sodium which won't cause algae.

this is why the crushed coral (calcium carbonate) is the better option it hits both GH and KH equally, and maintains them in the safe range for the tank and the pH controls it's release, and as the water shifts alkaline or acid but even the slightest, it buffers that to keep it steady and not shift.

if you insist on amending the water instead. it's going to be trial an error and doing it in buckets that sit for 24 hours before amending, and measures noted so you can reproduce the results when you settle on a dosing that works.
the "buffers in a bottle" will have you shifting the pH acid or alkaline and one cancelling the other out and you not hitting what you want to be because your KH (carbonates) isn't high enough to make them stick,

Like Seachem Alklaine Buffer, it's a proprietary mixture of salts, no potassium. this raises pH and creates KH (doseage if 1 teaspoon per 20g raises dKH by 2.8........

The Seachem Acid Buffer is no magnesium, and still a proprietary mixture of salts. this lowers pH and Converts carbonate alkalinity (KH) into available CO2.

so both products are sodium forms of carbonate (easier to tell with the Alkaline Buffer than the acid buffer) . they will raise or lower pH and "buffer it" to where you want it, but theres' nothing to KEEP it where you want it. you'll wind up pushing your dKH up, and the pH with it, then using the Acid buffer to take the pH back down, and the KH with it, and then back up again. it's even less stable of a method because it's amending the pH THROUGH playing with the KH instead of amending the KH to get a stable pH.

And all said and done, a stable pH is what you need, a little high, a little low the fish can and will acclimate to it and it will be fine. it's the wild swings that are damaging to the fish, the instability of the pH that kills.them. raising KH will get you where you want to be, raising KH and GH together and in balance with each other will keep you where you want to be for pH. and putting in a half pound of crushed coral once a year or so in the substrate would get it done.

up to you on how to proceed.

I stopped by petsmart and only saw one large bag of crushed coral for "marine/reef" tanks. I assume it would be fine, but decided not to buy it. Instead I came home and dug up some of my substrate and added 1/4 pound of oyster shells, then covered that with the original substrate.

I'll keep an eye on the ph, KH, and GH to see if I need to add more or take some of this out.

Thank you for the advice. I hope this will keep the Sonic the Betta and his Mystery Snail sidekick happy.

First test after 45 minutes: pH 7.3, KH 2.5, GH 5 I did about 15-20% water change total today. My conditioned tap water is KH 4, GH 5, pH 7.8 (after 24 hours or several hours of aeration).

 

A quarter pound of oyster shells will do something, but might not be enough, it's 95% calcium carbonate though, and a great start at least to getting the pH stable. your GH and KH should both come up and match, and then pH will go up or down depending on what it needs to do once the KH comes up.
See where the 1/4 pound gets you, in a day or two, then add or subtract like you said. if both are balanced between 4-8dKH then your pH should level off and stabilize also right in that straight 7 range.

if you want or need to go up or down from there it should just be an easy adjustment dosing pH up or down for the volume of water and the KH will hold it where you put it after that. calcium carbonate available assuming the oyster shells are broken up enough so it will become available. Like I think I said earlier or maybe not you could chuck a couple pounds of limestone rock as part of the scape but only the surface area is shedding calcium carbonate, all the rest is locked up in the middle and unavailable, it's not a good source like that.
Best of luck it should absolutely work once you have enough

 

It's such a relief to have woke up this morning without a pH crash. It appears this is working. I have bought some time to find a larger tank. Thanks for all the advice.