low ph during vinegar dosing / solutions?

[Randy Holmes-Farley]

I do not recall the color of mine, but I do not think it was darker than a typical beer.

 

[Clownfishy]

I did not realise working out what is safe/good Calcium Hydroxide was going to be so complicated! Everything food grade I can find in the UK looks like it has been repacked and sold by some unknown company. I will keep searching but might just order Seachem kalk as I am assuming this would be of good purity. Makes you wonder what I have been putting in my aquarium all these years as Kalkwasser. I thought I was buying high grade at 98% purity!

Here is the best I have come up with so far -

Specification
Molecular Formula: Ca(OH)2

Molecular Weight: 74.09

Calcium Hydroxide (Ca(OH)2): >97.98%

Calcium Carbonate (CaCO3):>0.55%

Magnesium Oxide (MgO <0.23%

Iron Oxide (Fe2O3): <0.03%

Aluminium Oxide (Al2O3): <0.04%

Silica (SiO2): <0.36%

Manganese (Mn)

Sulphur (S): <0.01%

Lead (Pb):

Arsenic (As):

Free Moisture: 0.53%

Available Lime (as Ca(OH)2): >97.06%

Neutralisation: 74.46%

 

[Randy Holmes-Farley]

Just bear in mind that color is often a poor indication of purity as substances we do not care much about can be pretty strongly absorbing, such as iron.

 

[Clownfishy]

So I have been thinking about what @Randy Holmes-Farley said in an above post about using food grade Calcium Hydroxide. I thought buying 98.7% "pure" Calcium Hydroxide was good and have been using it in my aquarium for years. As mentioned above, I attempted to make the vinegar kalk carbon mix and the color it mixed using my "pure" Calcium Hydroxide concerned me (first picture). I searched for food grade Calcium Hydroxide but the only people selling it were unknown sellers on eBay so I brought Seachem Kalkwasser. The first thing I did was to mix up a new batch of Kalkwasser for my Kalkwasser container which I dose during the night. The difference in color was night and day. Before, it would always mix with a slight brown tint in the water and the powder that settled at the bottom was a dark cream color. Using Seachem Kalkwasser it mixes completely clear and the powder stays white.
I then mixed up a new batch of vinegar Kalk carbon mix and the difference in the saturated color is unreal (second picture). As @Randy Holmes-Farley mentions, color is not a perfect measure of purity but I feel a lot happier using the Seachem Kalkwasser. It will be interested to see if I notice any difference is calcium and alkalinity levels just swapping out the Calcium Hydroxide.

Many thanks to @Randy Holmes-Farley. If it was not for him, I may have never known I have been using low grade Calcium Hydroxide.

Tomorrow, I plan switching from dosing NOPOX to the vinegar kalk mix so I will update this thread on the differences I observe.

 

[Clownfishy]

One other question about how much Calcium Hydroxide to mix into the vinegar. I keep adding it and gently shake the container and it mostly mixes and leaves a little bit on the bottom. I leave it to stand for several minutes and it keeps dissolving so I add more and keep repeating. I assume I keep doing this until it cannot dissolve anymore and that the Calcium Hydroxide powder remaining on the bottom of the container will no longer dissolve and at that point, I know I have mixed enough? Just wondering if you can over dose the amount of calcium hydroxide?

 

[leo carvalho]

another option would be to try to raise the pH in a way unrelated to the dosage of the carbon source. in my tank, i solved the low pH problem by connecting a hose to the skimmer and taking it outside. after a few days the improvement is very good.

 

[Clownfishy]

another option would be to try to raise the pH in a way unrelated to the dosage of the carbon source. in my tank, i solved the low pH problem by connecting a hose to the skimmer and taking it outside. after a few days the improvement is very good.

Hi, thanks for the suggestion. I already have a C02 scrubber and my pH rarely goes above 8.03. If I do not carbon dose, my nitrates and phosphates rocket and I think that is what is keeping my pH low. I am going to test dosing vinegar/kalk mix and see if that helps at all, if not, I think I need to look at an algae reactor or some other way of reducing my nutrient levels but I will leave that for another thread. I want to conclude if adding kalk to the vinager dosing helps with the pH.

 

[Randy Holmes-Farley]

One other question about how much Calcium Hydroxide to mix into the vinegar. I keep adding it and gently shake the container and it mostly mixes and leaves a little bit on the bottom. I leave it to stand for several minutes and it keeps dissolving so I add more and keep repeating. I assume I keep doing this until it cannot dissolve anymore and that the Calcium Hydroxide powder remaining on the bottom of the container will no longer dissolve and at that point, I know I have mixed enough? Just wondering if you can over dose the amount of calcium hydroxide?

Yes, that's pretty much what I did: dumps in so much that no more dissolves. It should take around 60 g per liter of 5% acidity vinegar, but there's nothing wrong with adding way more and you can reuse the solids again if you want.

 

[Randy Holmes-Farley]

another option would be to try to raise the pH in a way unrelated to the dosage of the carbon source. in my tank, i solved the low pH problem by connecting a hose to the skimmer and taking it outside. after a few days the improvement is very good.

One intent to adding calcium hydroxide to the vinegar is tp eliminate the immediate pH drop that comes when dosing vinegar manually or otherwise all at once. Actions to raise the tank pH wouldn't stop that effect, but putting calcium hydroxide in the vinegar does.

 

[Clownfishy]

Yes, that's pretty much what I did: dumps in so much that no more dissolves. It should take around 60 g per liter of 5% acidity vinegar, but there's nothing wrong with adding way more and you can reuse the solids again if you want.

Thanks, I think I am about there with just a small amount of undissolved powder at the bottom of the container. I did not measure it but 60g does sound about the amount I added to the 1 litre container.
Will start dosing it Saturday and will continue to test the water to check for any major changes.

 

[Randy Holmes-Farley]

Thanks, I think I am about there with just a small amount of undissolved powder at the bottom of the container. I did not measure it but 60g does sound about the amount I added to the 1 litre container.
Will start dosing it Saturday and will continue to test the water to check for any major changes.

It's good to make sure there is excess because the high pH it ensures will prevent bacterial growth.

 

[Clownfishy]

Good to know, I will add another teaspoon or two.

 

[leo carvalho]

One intent to adding calcium hydroxide to the vinegar is tp eliminate the immediate pH drop that comes when dosing vinegar manually or otherwise all at once. Actions to raise the tank pH wouldn't stop that effect, but putting calcium hydroxide in the vinegar does.

yes, you are correct. but if the pH fluctuates between. 8.2 and 8.5 as here in my tank, these drops in vinegar dosage end up being less significant. moreover, both measures can be taken. =)

 

[Randy Holmes-Farley]

yes, you are correct. but if the pH fluctuates between. 8.2 and 8.5 as here in my tank, these drops in vinegar dosage end up being less significant. moreover, both measures can be taken. =)

Ok, I certainly understand there are other ways to deal with pH, but there is no better way, IMO, to manually dose vinegar than as a saturated calcium hydroxide solution.

 

[Clownfishy]

It has only been 1 day switching my dosing from NOPOX to the Vinegar Kalk mix so this is clearly not be an accurate picture as I may not have the dosing volume correct. However, my pH has never been this high ever since setting up the aquarium back in November 2021. As you can see below, I hit a pH of 8.13 at its peak What is also interesting, I did not see my ORP drop off a cliff as I normally see after the first hour dosing NOPOX (please see my previous posts in this thread).

Dosage
Previously, my Apex DOS started dosing NOPOX at 9:00am at 0.1ml every 13 minutes or so adding a total of 3.5ml until 16:00. I recently extended the dosing period to 17:30. Now, my Apex DOS doses 0.2ml of the Vinegar Kalk mix every 10 minutes during the same time but I upped my dosage to a total of 10ml as I have been advised it would require additional volume compared to NOPOX.

pH
Previously, I would be lucky for my pH to hit 8.03 by late afternoon, today it hit 8.13.

ORP
As you can see from the graph below, previously my ORP would drop over 100 within a 2 hour window. Now (3rd June) my ORP dropped just 30 over approximately 3.5 hours

Alkalinity / Calcium
I will be testing Alkalinity and Calcium at least twice a day as I switch over to the Vinegar Kalk mix. Before I switched from NOPOX my Alk was 11 and my Calcium 465. These are quite high and before switching to the Vinegar Kalk mix, I have had to reduce my 2 part dosing from 11ml a day to 7ml per day. I have put this down to changing the way I have been dosing Kalkwasser the last couple of weeks. I now have a magnetic stirrer which gently mixes my kalk 3 hours before I start dosing it so I am assuming it is super saturated (not slurry) before dosing. I cannot think of anything else I have changed which would have caused a reduction in the uptake of 2 part and an increase in calcium, which is normally 450 and my alkalinity, which is normally 9.5 - 10.

Nutrient Levels
I have always had high nutrient levels (hence originally dosing NOPOX) and my phosphate levels were previously between 0.18 - 0.23 dosing NOPOX at 3.5ml a day. I took a reading this morning before starting dosing the Vinegar Kalk mix and for some reason it had jumped to 0.27. No idea why the phosphate level was higher as nothing has changed so I took another reading at 13:00 and it read the same 0.27. I then took another reading at 17:30 and it was 0.26.
Nitrate levels have previously sat at around 8 - 10 and the reading I took this morning before the Vinegar Kalk dosing was 9.6. At 17:30 today, it was 9.5.
I will continually check these levels daily over the next few weeks to make sure I am not reducing them too low or if they start to rise, I will obviously increase my dosing volumes

I will keep updating this thread but I can say that day one has made a big different to my pH levels and prevented ORP dropping rapidly, just need to see what differences, if any, I see with my nutrient levels.

Many thanks @Randy Holmes-Farley for you advice on this topic. I am always nervous making changes to my reef so your guidance on this is greatly appreciated.

 

[Clownfishy]

A quick update for those people like me, who have never tried dosing the Vinegar Kalk mix. Today (day 2) was never going to be an easy day to monitor for any changes as it is a maintenance day for my aquarium so that messed around with my water parameters for the day. However here goes -

Nutrients
So after blowing all the detritus off the rocks and cleaning the pumps and glass, I obviously caused a fair bit of phosphate to dissolve into the water and my phosphate hit 0.4. After a few hours and my regular weekly 20% water change, it dropped down to 0.29. I did not test Nitrates today.

Dosage
I decided to increase my Vinegar Kalk dosage from 10ml to 12.5ml for the next few days to see if I can bring my phosphate down a bit and I feel I am not quite dosing enough. I did see a very slight bacteria bloom and my skimmer started to skim wetter as it was pulling out most of the bloom.

pH
Overnight, my pH dropped to a low of 7.98 for a few minutes but the rest of the time the low was 7.99 and 8.0 which is unheard of in my aquarium as I normal hit 7.86 -7.95 so I am very pleased with that. Today I did a water change and that always boosts my pH temporarily to about 8.1. At the time of starting my water change, my pH was 8.06 and after the water change it jumped to 8.12. What was nice to see, my pH continued to rise to a high of 8.18 as the Apex DOS continued to dose 0.2ml of Vinegar Kalk every 14 minutes. I suspect that will be a little hard to hit again but it is nice to see the Vinegar Kalk boosting my pH even higher after the water change so very pleased with that as I have never seen that before.

ORP
Even stirring up all the detritus my ORP only dropped a total of 40 and by the evening, it returned back to its normal level of 310 - 320. I am not seeing it plummet like it did dosing NOPOX.

Alkalinity
My alkalinity rose a bit over night into the morning from 11 to 11.2. I have dropped my 2 part dosing down another 1ml to now just 6ml per day to see if I can bring the levels back down to 10.

Summary
So far, I am VERY happy making the switch but clearly the real test is to see it control my phosphate and Nitrates levels so time will tell on that. What I can say is that NOPOX definitely suppresses pH as I observed an immediate jump in pH moving over to Vinegar kalk mix. Tomorrow, will be a normal day so I plan on performing a full range of tests in the morning before the vinegar kalk dosing starts and then again in the evening.

Hope the above is useful for people considering trying to boost their pH while carbon dosing. As mentioned, it is early days so will report back soon on the nutrient levels.

 

[Clownfishy]

@Randy Holmes-Farley when you dosed Vinegar Kalk mix, did you dose during the day or night? I was thinking as I am getting such a boost of pH using it, I wonder if it better to use it during the night to maintain the pH after lights out?

 

[Randy Holmes-Farley]

I dosed in the late AM since it can lower O2 in the period of time after dosing.

 

[Clownfishy]

After leaving the Vinegar Kalk mix dosing container to stand for a few days, the brown particles seem to have sank to the bottom of the container. I wonder if I am better off siphoning the clear vinegar mix out and throwing the rest away? The brown stuff does not look good and no idea what this is.

 

[Randy Holmes-Farley]

The settle brown is probably things like iron oxide. I'd not dose it, but I wouldn't go to extremes trying to avoid it.