low ph during vinegar dosing / solutions?

[Randy Holmes-Farley Verified Community Expert]

Thanks Randy for your advice on this. It does not seem there is much information on mixing Calcium Hydroxide into Vinegar so I am trying to get the mix right.
As my pH drops like a stone at night (3 people and 2 dogs breathing out C02 at night!), I thought I might try a couple of things first before I turn off the Kalkwasser dosing although, I think you have possible found the issue.
For 2 days I reduced the vinegar kalk mix by 1/4 and my alk never came down. I am now going to do the following to prove what is raising my alk.

1. Change the magnetic stirrer on the Kalkwasser container to mix first thing in the morning right after the last dose and only for 15 minutes reduced from 30mins. Test alk daily to see if I see a slight drop.
2. If no noticeable change from point 1, turn off magnetic stirrer on the kalk container completely so there is no mixing of Kalkwasser.
3. If both 2 and 3 have not dropped my alk, stop dosing Kalkwasser for a night or 2.

I am now thinking either 1 or 2 might do the trick. If that is not the case and it is 3, then whatever "pure" Calcium Hydroxide I was using before is clearly not as pure as Seachem Kalkwasser.

I assume you would not expect much alk in the vinegar mix as opposed to the alk from Kalkwasser?

The potency of the settled vinegar kalk mix can be calculated exactly. It is about 21 times as potent as kalkwasser. So 10 mL has alk potency similar to 210 mL of kalkwasser.

 

[Randy Holmes-Farley Verified Community Expert]

@Randy Holmes-Farley , while I will do the test listed in my last reply, I thought I would make up some more vinegar kalk mix. After my last experience where there was a lot of kalk left at the bottom mixing 60g with 1 litre of vinegar, this time I halved the kalk to 30g. As you can see, I am still getting about an inch of undissolved kalk settling at the bottom of the container even with vigorous mixing. The remainder of the liquid is cloudy but I will let it settle over night.
Would you expect that much kalk left over?

It’s hard to judge amounts by the look, but it’s good to have excess.

 

[Clownfishy]

Thanks Randy for your advice on this. It does not seem there is much information on mixing Calcium Hydroxide into Vinegar so I am trying to get the mix right.
As my pH drops like a stone at night (3 people and 2 dogs breathing out C02 at night!), I thought I might try a couple of things first before I turn off the Kalkwasser dosing although, I think you have possible found the issue.
For 2 days I reduced the vinegar kalk mix by 1/4 and my alk never came down. I am now going to do the following to prove what is raising my alk.

1. Change the magnetic stirrer on the Kalkwasser container to mix first thing in the morning right after the last dose and only for 15 minutes reduced from 30mins. Test alk daily to see if I see a slight drop.
2. If no noticeable change from point 1, turn off magnetic stirrer on the kalk container completely so there is no mixing of Kalkwasser.
3. If both 2 and 3 have not dropped my alk, stop dosing Kalkwasser for a night or 2.

I am now thinking either 1 or 2 might do the trick. If that is not the case and it is 3, then whatever "pure" Calcium Hydroxide I was using before is clearly not as pure as Seachem Kalkwasser.

I assume you would not expect much alk in the vinegar mix as opposed to the alk from Kalkwasser?

An update to the 3 points I said I would do in the above post for those that are interested.

I have now performed point 1 and 2 and I did not see any real reduction in Alkalinity so before I moved onto point 3, I created point 2a!

2a. Reduce Vinegar Kalk mix and replace volume with pure vinegar (a separate dosing).

I reduced Vinegar Kalk mix from 20ml per day to 10ml per day and added 10ml of pure vinegar separately and my alk reduced from 12 to 11. Therefore, on the face of it, it could well be the vinegar kalk mix causing the alk increase.

The other observation I have noticed is that phosphate have gone up with this mixture of pure kalk and vinegar kalk mix so I added another 5ml of pure Vinegar today making my dosing 25ml of pure vinegar and 10ml of vinegar kalk mix . This is a total of 35ml of vinegar in a 75litre (20 US gal) aquarium which seems a lot to me. Even with this amount of dosing, my phosphates are 0.44. When I was dosing 3ml per day of NOPOX, my phosphates where 0.15.

I am really reluctant to perform option 3 as my pH plummets at night and I cannot see how I can live without the pH boost from the kalkwasser during the night. Therefore, I am now considering switching back to NOPOX as although I have seen amazing pH improvements from the vinegar kalk mix, I am getting a little concerned at how much vinegar is going into my system and how much more I would need to dose to get me back to where I was previously.

Its a catch 22, I can either have -

• High alk, high pH and high phosphate (with vinegar kalk mix)
• Normal alk, low pH and low phosphates (with NOPOX)

One solution to improve the first bullet point is to increase the SPS corals I have thus increase the alk consumption which would offset the high alk. That may take some time so I am now considering switching out the pure vinegar and temporarily using NOPOX while keeping a low dosage of the vinegar kalk mix (about 5ml) so I hopefully reach a balance until I have more SPS corals.

I will update this thread with my next tests as I would like to keep on record the results for those people who have high nutrient levels and are battling with low pH due to carbon dosing.

 

[Clownfishy]

Another update for those of us that are trying to offset the drop in pH when dosing carbon. As mentioned in my last post, I wanted to increase the uptake of alkalinity by increasing the SPS corals in my aquarium. Just a recap, this was because I was hitting a limit on the amount of vinegar kalk mix I could add as my alkalinity was hitting 12.

Before I get onto the addition of SPS corals, I wanted to stabilize the carbon dosing and after a lot of daily testing of phosphate and alkalinity and trying different dosing levels, I have now been dosing 10ml of vinegar kalk mix and 1ml of NOPOX which maintained my alkalinity at 11.3 and my phosphate at 0.44ppm. Now I know that phosphate of 0.44ppm is very high but I wanted a stable baseline. I temporarily raised the NOPOX dosing to 3.5ml per day but the corals did not like that even though the phosphate dropped to 2ppm.

I then added 2 more SPS corals and over the next few days, my phosphate dropped to 0.41-0.39ppm and alkalinity to 10.9. This is logical but it was good to see the plan on adding corals could resolve my high nutrient and low pH problem.

The next thing I did was increased my lighting intensity to see if I could increase the uptake of C02 and phosphate by the corals. With increasing the lighting intensity and with a 20% water change, my alkalinity dropped to 10.5 and phosphate between 0.3 - 0.36ppm.

I have not increased my vinegar kalk mix dosing yet as I want my alkalinity to drop to 10. If that happens, I will start to increase my vinegar kalk mix and reduce my NOPOX dosing. Ultimately , I want to get to the point where I no longer dose NOPOX which impacts my pH and replace it with vinegar kalk mix which increases my pH while providing carbon.

I have just adding 4 more SPS frags to see if I can reduce my alkalinity and phosphate further so I will be testing daily for the next few days. I am also interested to see if the drop in phosphate helped by water change is maintained. If phosphate does not increase, I may do another 20% water change to see if I can reduce phosphate back a bit more.

For information, I dose NOPOX between 11:00-16:00 with 0.1ml being dosed every 33 minutes. Dosing like this prevents any reduction in pH. I dose the 10ml vinegar kalk mix between 08:00 - 20:00. Also, I still no longer dose my 2 part as my alkalinity is rock solid with no fluctuations. For those people who have high nutrient levels, I can totally recommend dosing kalkwasser at night and vinegar kalk mix during the day. Dosing kalk continuously through this method is all the dosing my aquarium needs making it a very cheap dosing method!

I will report back in about a week or so once I know what effects the additional of the 4 SPS frags are having but so far, I am very pleased with the pH jump and stable Alkalinity, calcium and magnesium levels. I will wait to report on pH levels as we are going through a bit of a heat wave here in the UK so I have my windows open all day. This is not providing a fair comparison as my C02 levels in the house are clearly lower than normal. Trust me, the heat wave wont last long in the UK so my C02 level will be back to "normal" allowing me to see what my real pH levels out at.

 

[Randy Holmes-Farley Verified Community Expert]

What is happening to nitrate during this period?

 

[Clownfishy]

What is happening to nitrate during this period?

I have only been testing that twice a week and it is tracking the phosphate in that when phosphate increases so does nitrate and when phosphate reduces, so does nitrate. I will be doing another test tomorrow so will post it then.
In the last two days, my Montipora has begun to bleach. Three different species all on separate rocks. 2 red and 1 green. I put this down to a mistake i made trying to compensate for the calcium rising so I added some alk in an attempt to balance things which then went up to 11.5. Now it has been that high before but I had it nicely sitting at 10.5 and it was coming down slowly. No other corals are showing any form of bleaching (yet!). I have just done a water change but this has now messed with the water parameters I am tracking so when i post the nitrate and phosphate levels, I suspect they would have dropped quite a bit from the water change. I was hoping I could consistently track nutrient reduction through carbon dosing and the corals taking up the nutrients as an experiment by tracking the progress of vinegar kalk mix as consistently as possible and then this happens!! This has shown me how hard it must be to perform controlled experiments in real science!!!
Still, I am absolutely amazed how good Calcium Hydroxide is as stabilizing alk/cal. I have used kalkwasser for years and I thought I knew its benefits but had never thought of using it in a vinegar mix. I really think this is unknown by many hobbyists with high nutrient reef aquariums and the stability it creates. I no longer dose 2 part just Calcium Hydroxide (kalk at night and vinegar kalk mix during the day). This is allowing me to dose Calcium Hydroxide 24/7 while reducing nutrient levels and it is as cheap as anything .
I need more corals as I need more alk consumption but from what I have seen, I believe both Nitrates and Phosphates will continue to come down.

 

[Clownfishy]

OK, things have taken a turn for the worse. Over the last 2 days, I have stopped dosing the vinegar kalk mix and reduced the kalkwasser dosing at night in an attempt to reduce my Calcium and Alkalinity. My corals are not looking good and most of the Montipora corals are bleaching (see pics below). I did a big water change yesterday and will do some big water changes for the next few days to see if it is water chemistry. I cannot be sure it is but the the only other change I have made was adding some new corals at the weekend so although they were dipped, maybe they have brought something in.

Water Parameters
Alk 11
Cal 470
Mag 1395
Nitrate 13.3
Phosphate 0.3
pH 8.34 (could be 8.14)
The difference in the pH is that during the weekend, I calibrated the probe (twice) and it jumped 0.2. I normally see a lower value when I calibrate the probe so although I calibrated it twice, I am not convinced. I will calibrate it again tomorrow and see what I get.
I have included the historical view of these parameters below. I am now just dosing 1ml of NOPOX per day and 200ml of kalkwasser each night on a 75l aquarium.

I will be sending off an ICP test but not sure if I am battling a chemistry issues or bacterial infection which started (well I believe it was a bacterial infection) taking out my lps some months ago but my SPS have been absolutely fine throughout this time and in fact, have shown impressive growth. Bleaching started 2 days ago and most other corals are either closed up or beginning to look like they are struggling.

Lets see if a few big water changes resolve this as it was going really well up until 2 days ago and although phosphate is high (it always has been), it was coming down nicely and I have managed to reduce the NOPOX dosing from 3ml a day to 1ml a day and I have never manged that before.

 

[Clownfishy]

OK, I think I may have found the culprit of my high alkalinity. Just tested my H20 Ocean Pro salt and it is 11.7 and calcium is 460. No wonder i cant get my alk down. Just ordered Red Sea Blue bucket which says it mixes up at levels of 8 alkalinity and 430 calcium. Therefore, I will be doing some big water changes to reduce the alk levels as I think this is why I am seeing bleaching of the corals. I switched to H20 Ocean Pro salt several weeks back and alk has been raising over that time. As I also started dosing vinegar kalk mix at the same time, I put it down to that. Never thought the salt would mix that high as i had used it before and it mixed to 9.9 alkalinity and 425 calcium. Just hope I can save the other corals and get back to my vinegar kalk mix experiment as it was going so well.

 

[Clownfishy]

With one single 20% water change with the Red Sea blue bucket salt, at long last my alkalinity is finally dropping. Another 20% water change and I will begin reintroducing the vinegar kalk mix.

 

[Miami Reef]

@Randy Holmes-Farley

Can I use a metal spoon to stir the saturated kalkwasser vinegar mix? I don’t have the lid of my pickle jar container.

Can I touch the saturated kalkwasser vinegar solution with nitrile gloves, or will it eat through it and damage my skin?

 

[Randy Holmes-Farley Verified Community Expert]

@Randy Holmes-Farley

Can I use a metal spoon to stir the saturated kalkwasser vinegar mix? I don’t have the lid of my pickle jar container.

Can I touch the saturated kalkwasser vinegar solution with nitrile gloves, or will it eat through it and damage my skin?

Nitrile gloves are fine. A brief stir with an ordinary kitchen spoon should be fine.

 

[Miami Reef]

Nitrile gloves are fine. A brief stir with an ordinary kitchen spoon should be fine.

Thank you Doc!

I went to get the supplies needed and I noticed I have a thick LDPE tube. I used it to stir it in.

 

[Miami Reef]

@Randy Holmes-Farley

50 mL of vinegar contains 2.5 grams (42 millimoles) of acetic acid. So if that is fully neutralized, it adds 42 milliequivalents of alkalinity to the tank. In 150 gallons (568 L), this is 42 meq/568 L = 0.074 meq/L = 0.2 dKH. Then there will be an very tiny amount of calcium hydroxide dissolved in the 50 mL.

Thus, the total alk and calcium added is small.

I’m dosing 40mL of vinegar that is saturated with kalkwasser in a 260 gallon tank.

About how much will that boost alkalinity per day?

Never mind.