can carbon dosing cause alkalinity increase?

[coralcruze]

Randy and reef community;

Wondering if you could help me understand if Carbon dosing either by vodka, bio pellet, or vinegar can cause an alkalinity spike?

I would think that in order to get a spike in alkalinity in a reef that you must add a product like sodium bicarbonate to raise Alk. As i understood Kalk or even a calcium reactor do not even boost this ion, rather just maintain its level. Interestingly, a friend reported that he saw an Alk boost above 11.5 dkh which he attributes possibly to vodka dosing.

Perhaps someone can explain in more technical terms if this is/is not even possible?

has anyone heard of this occurrence?

Thanks in advance!

 

[Randy Holmes-Farley]

If you have a lot of existing nitrate and it gets consumed (by macroalgae, bacteria, corals, etc.) so that the actual nitrate level drops, alk will rise.

Here's a copy and paste from an article of mine:

In the absence of O2, and taking the nitrogen species completely to N2 (which may happen in several reaction steps), we have the following overall reaction:

organic + 124 NO3– + 124 H+ → 122 CO2 + 70 N2 + 208 H2O

It can be seen that the process above produces alkalinity (by consuming H+). In fact, it is the exact same amount of alkalinity that was depleted when the nitrate was originally formed from foods, so the net effect of the nitrogen cycle on alkalinity is zeroed out.

 

[Randy Holmes-Farley]

As i understood Kalk or even a calcium reactor do not even boost this ion, rather just maintain its level.

That part is wrong. Both limewater (kalkwasseer) and calcium carbonate reactors will add alk and can raise it if you add more than the demand.

For limewater:


Ca(OH)2 ---> Ca++ + 2(OH-)

The calcium ions in the solution obviously supply calcium to the aquarium, and the hydroxide ions supply alkalinity. Hydroxide itself provides alkalinity (both by definition and as measured with an alkalinity test), but corals consume alkalinity as bicarbonate, not hydroxide. Fortunately, when limewater is used in a reef aquarium, it quickly combines with atmospheric and dissolved carbon dioxide and bicarbonate to form bicarbonate and carbonate:

OH- + CO2 --> HCO3-

OH- + HCO3 ---> CO3-- + H2O

 

[coralcruze]

Thank you Randy... this is going to take me a while to understand, especially the chem calcs

If you have a lot of existing nitrate and it gets consumed (by macroalgae, bacteria, corals, etc.) so that the actual nitrate level drops, alk will rise. In fact, it is the exact same amount of alkalinity that was depleted when the nitrate was originally formed from foods, so the net effect of the nitrogen cycle on alkalinity is zeroed out.

My friend is still in the process of lowering Nitrates and dosing vodka but is getting close to the target range. At the time my friend was experiencing issues with high Alk he had Nitrate at 10 (as tested with red sea kit) and Alk at 8.5. Nitrates then dropped to 5 and Alk raised to about 12 dkh. Which caused some bleaching of corals. The time frame we are talking about is several weeks as he has been following the recommended vodka regiment closely. According to your calculations, it even possible to raise Alk by that much when Nitrates dropped only 5 points?

I also dose vodka and before that bio pellets and don't ever recall an Alk spike of any kind. at least not like he experienced...

 

[coralcruze]

oh important to note that he was dosing two part (b-ionic) daily and still continues. ESV recommended that he stop dosing when this occurred.

 

[Randy Holmes-Farley]

FWIW, the alk added is not especially large. The alkalinity gain is 0.8 meq/L (2.3 dKH) for every 50 ppm of nitrate consumed.

 

[coralcruze]

ok... that's a fairly low amount that Alk would rise by. So basically since he only dropped about 5 dKH in the time frame mentioned... that's about 1/10th of 0.8 meq/L (2.3 dKH) = .23 dKH rise.. I think that there must have been something in addition to the above at play to raise the Alk by the amount he was actually seeing.

As always, thanks so much for all of your help Randy, i really appreciate it and will let him know.

 

[coralcruze]

That part is wrong. Both limewater (kalkwasseer) and calcium carbonate reactors will add alk and can raise it if you add more than the demand.

For limewater:


Ca(OH)2 ---> Ca++ + 2(OH-)

The calcium ions in the solution obviously supply calcium to the aquarium, and the hydroxide ions supply alkalinity. Hydroxide itself provides alkalinity (both by definition and as measured with an alkalinity test), but corals consume alkalinity as bicarbonate, not hydroxide. Fortunately, when limewater is used in a reef aquarium, it quickly combines with atmospheric and dissolved carbon dioxide and bicarbonate to form bicarbonate and carbonate:

OH- + CO2 --> HCO3-

OH- + HCO3 ---> CO3-- + H2O

Thanks for correcting me Randy... This is why I use your recommendation of adding Kalk to the system in addition to calcium reactor for that very reason and cant be happier that I did since. I also love the added benefit of one balancing the other in terms of PH. I get a PH boost but fairly stable day/night. LOVE IT!

Randy as always thank you sir!!!

 

[nano reef]

I realize this is very old thread but was doing some research on uping alkalinity and lowering nitrates. First I should start by saying my 36 gallon bowfront is about 5 months old. I added corals about 3 weeks ago but to many at a time because I won some of them then got carried way with buying from ebay auction they had and live sale so I added about 16 frags. I have never dosed anything to the tank and keep everything up with weekly water changes of about 30 percent with IO reef crystals. I wasnt running my skimmer either because it had a leak in it. i have been running it now for about 5 days and seems to be dialed in but not changing numbers but pulling out some dark skimmate.

Once I started feeding reefroids the nitrates have shot up to 80! I question the api kit because the lid was off so buying anew kit before I start using the nopox that came with the preowned aquarium. I was going to start dosing 2 part with soda ash, or red sea, possibly brs. I am assuming I should start the nopox first before I attempt to mess with the alk? I hate to let the bottle go to waste..lol Is there any reason I should not use this method and try another? I have about 30 or more marine pure balls in m y sump but that hasnt helped with nitrates. They have usually been around 10 after a wc and maybe up to 20 right before. I also have abag of gfo in the filter sock. I am guessing I should remove that asap. I also have a api for phosphates and looks like it between 0 and 0.25. I am getting a low range better test kit since it so hard to read.

I also have stopped feeding corals and scared to start back because reefroids is some potent nitrate inducer! I was thinking about using red sea coral nutrition or reef energy as a food source at first before I start actually feeding corals. Will that have as big effect on nitrates? I hope it will keep them nourished in the meantime.
I would apreciate any help Randy

 

[rmurken]

Are you testing for Ca/Alk? I would pay attention to that now that you have a bunch of frags in the tank. Even more so if you have significant coralline growth.

IMO, I’d hold off on nopox and make sure you have a handle on the Ca/Alk first. Not feeding your corals is fine, and should help with your NO3 and PO4 (assuming your levels are actually high). And whether you ever need something like nopox depends on your system and your goals, so just not a thing you need to rush.

Testing. The API PO4 test really isn’t sensitive enough for a reef tank. The NO3 test isn’t particularly sensitive or precise, but it’ll give you a general idea of whether you have a lot or a little NO3. TBH, probably good enough. If the bottle was damaged, wise to replace.

Bottom line, focus on Ca and Alk. Forget the nopox. Taking a break from feeding corals good.

 

[nano reef]

Are you testing for Ca/Alk? I would pay attention to that now that you have a bunch of frags in the tank. Even more so if you have significant coralline growth.

IMO, I’d hold off on nopox and make sure you have a handle on the Ca/Alk first. Not feeding your corals is fine, and should help with your NO3 and PO4 (assuming your levels are actually high). And whether you ever need something like nopox depends on your system and your goals, so just not a thing you need to rush.

Testing. The API PO4 test really isn’t sensitive enough for a reef tank. The NO3 test isn’t particularly sensitive or precise, but it’ll give you a general idea of whether you have a lot or a little NO3. TBH, probably good enough. If the bottle was damaged, wise to replace.

Bottom line, focus on Ca and Alk. Forget the nopox. Taking a break from feeding corals good.

I didint realize that I left out the numbers but alk is 7 and nitrates are a whopping 80! I retested it so many times because I coulnt believe it. It is missing the lid but its been missing for over a month and was testing between 10 and 20.

I was going to change water today but didnt get to do it. i am always on time with changes but dreading doin it today because i have threw my back out and in a lot of pain. Plus both of my daughters came to visit. Certainly will tomorrow. My alk is usually 9 or so and nitrates have been anywhere for 10 to 20, so been needing to lower for a while anyway. I never had a skimmer though until last 5 days or so.

I was aking about which I should take care of first was because I read that lowering my nitrates would lower my alk so thats why I thought I should take care of that first because after nitrates come down I may not even need to lower alk. Actually they were fine until the nitrates shot up!

Its just a little scarry not having dosed before and having two things to do Plus I have even more frags coming! Quite a lot too...lol. Getting carried away with my winnings from unique corals! LOL Plus each time they had my order on hold. All the while their having ebay auctions and live sales plus when I starts buying them each time my nitrates werent to bad! Defietly wasnt thinking about the big picture and how the heck am I going to feed them all when my tank isnt used to a bioload like that? What do you think about using reef energy (which you know is carbs and amino acids to feed) ? Not meaning right now but once I get things under control. I dont supposed they can starve to death, just take a halt from growing!

 

[rmurken]

Top thing is don’t let your Alk get any lower. I would start dosing two-part (Ca/Alk together) to a steady target at least in the mid-7’s or 8. If you’re using the API test, it should be enough to distinguish between 7 and 8. Get yourself a Ca test too if you don’t have one. Aim for the 400’s.

As for nitrates, I would not rush to take any action until you have a reliable test kit. High nitrates aren’t going to kill anything overnight. A fresh API nitrate test will verify whether your levels of that are actually that high. You might consider investing in a more sensitive test once you’re done with the API (or get picky like a lot of us).

Good chance water changes and not feeding will help your nitrate situation without carbon dosing.

Nopox (i.e.., carbon dosing) is a longer-term strategy and not to be toyed with, so don’t rush it. Read up on vodka too—not clear Nopox adds value on top of good old vodka.

 

[Randy Holmes-Farley]

I realize this is very old thread but was doing some research on uping alkalinity and lowering nitrates. First I should start by saying my 36 gallon bowfront is about 5 months old. I added corals about 3 weeks ago but to many at a time because I won some of them then got carried way with buying from ebay auction they had and live sale so I added about 16 frags. I have never dosed anything to the tank and keep everything up with weekly water changes of about 30 percent with IO reef crystals. I wasnt running my skimmer either because it had a leak in it. i have been running it now for about 5 days and seems to be dialed in but not changing numbers but pulling out some dark skimmate.

Once I started feeding reefroids the nitrates have shot up to 80! I question the api kit because the lid was off so buying anew kit before I start using the nopox that came with the preowned aquarium. I was going to start dosing 2 part with soda ash, or red sea, possibly brs. I am assuming I should start the nopox first before I attempt to mess with the alk? I hate to let the bottle go to waste..lol Is there any reason I should not use this method and try another? I have about 30 or more marine pure balls in m y sump but that hasnt helped with nitrates. They have usually been around 10 after a wc and maybe up to 20 right before. I also have abag of gfo in the filter sock. I am guessing I should remove that asap. I also have a api for phosphates and looks like it between 0 and 0.25. I am getting a low range better test kit since it so hard to read.

I also have stopped feeding corals and scared to start back because reefroids is some potent nitrate inducer! I was thinking about using red sea coral nutrition or reef energy as a food source at first before I start actually feeding corals. Will that have as big effect on nitrates? I hope it will keep them nourished in the meantime.
I would apreciate any help Randy

I would always focus on alkalinity. Everything else is less important.

The rise in alk from nitrate reduction/organic carbon dosing is going to be a slow process. It is not going to happen overnight. It's a fine approach.

 

[lagnew904]

FWIW, the alk added is not especially large. The alkalinity gain is 0.8 meq/L (2.3 dKH) for every 50 ppm of nitrate consumed.

My apologies for bringing up an old post. I started dosing nopox last week with a starting point of 50+ nitrate and alk 8.5dKH.

The end goal is to get the nitrate to roughly 10-15 ppm. Is the ratio of 2.3 dKH gain on 50ppm nitrate reduction completely accurate? Does skimming reduce the alk gain or is this already converted at consumption prior to skimming?

As of now I'll stop dosing alk to see if the gain would compensate for daily dosing/consumption.

 

[HuduVudu]

Does skimming reduce the alk gain or is this already converted at consumption prior to skimming?

The alk gain is from anaerobic decomposition of the nitrate. The speed of the alk gain and the nitrate reduction is dependent on the capacity of that decomposition in your system. Skimming doesn't do anything to the existing nitrate unless you are carbon dosing. Whereby the bacteria will consume the nitrate and then be removed from the system by the skimmer. For this route no alk is created because there will be no anaerobic breakdown to produce the alk.

 

[lagnew904]

The alk gain is from anaerobic decomposition of the nitrate. The speed of the alk gain and the nitrate reduction is dependent on the capacity of that decomposition in your system. Skimming doesn't do anything to the existing nitrate unless you are carbon dosing. Whereby the bacteria will consume the nitrate and then be removed from the system by the skimmer. For this route no alk is created because there will be no anaerobic breakdown to produce the alk.

Understood. I was thinking that but I wanted to confirm. I'm carbon dosing and running skimmer 24 hours.

 

[Randy Holmes-Farley]

. Is the ratio of 2.3 dKH gain on 50ppm nitrate reduction completely accurate? Does skimming reduce the alk gain or is this already converted at consumption prior to skimming?

It is completely accurate, but if spread out over time will get swamped out by other additions and subtractions of alkalinity.

Skimming or not does not impact the ratio.

 

[crabgrass]

It is completely accurate, but if spread out over time will get swamped out by other additions and subtractions of alkalinity.

Skimming or not does not impact the ratio.

Reviving a really old thread. So if this was spread out, and we were dosing something like AFR, and trying to target all, would this lead to more of an imbalance?

Eg if alk/ca we’re at there sweet spot. My alk spikes because of N reduction via carbon dosing. I lower AFR to compensate for it. Now my CA is lower than I want?

I understand The above scenario could happen naturally anyway - depending on corals and other stuff in my tank.

 

[Randy Holmes-Farley]

Reviving a really old thread. So if this was spread out, and we were dosing something like AFR, and trying to target all, would this lead to more of an imbalance?

Eg if alk/ca we’re at there sweet spot. My alk spikes because of N reduction via carbon dosing. I lower AFR to compensate for it. Now my CA is lower than I want?

I understand The above scenario could happen naturally anyway - depending on corals and other stuff in my tank.

If alkalinity is being added because of a nitrate reduction, and one stops a balanced alk/calcium dosing method to keep alk from rising, then yes, there will be a small calcium reduction, but the emphasis is on small.

If you drop nitrate by 50 ppm, the alk boost is 2.3 dKH.

If you had added that same alk via AFR, you would only have added 16 ppm of calcium.

If that 16 ppm of calcium concerns you (when the range of OK calcium is at least 400-550 ppm), then I'd recommend adding it as calcium chloride, or the calcium part of a two part.