Carbon Dosing with AFR Questions

[Fish Fan]

I know you are looking to feed the corals as well as lower nitrates but I recently added some Media Seachem Denitrate as I had a similar issue (high nitrates, low phosphates) and my Nitrates went from 20-40PPM to around 5-10PPM and have been stable for over a week and my phosphates stayed the same. I think its just high surface area mini pumice rocks for beneficial bacteria to grow but it really works. I was worried it would bottom out my nitrates but I have not had that issue and I still overfeed slightly (not intentionally lol) I do have fish and I know you currently do not but thought I would mention it. I am in a 20 Gallon setup. It does say it stabilizes at 5PPM nitrates but thought I would mention that as my nitrates were going from 5 to 10 to 20 to 40 all within a couple of days and that fixed my issue. I may look at AFR for dosing once I get my parameters where I want them, right now I just use foundation red sea products.

Thank you for your reply and help! I will take a look at the Seachem product you're suggesting, though I am skeptical of products like this. I don't get what it does that rock rubble can't? Thank you again for your help!

 

[TheNative192]

Thank you for your reply and help! I will take a look at the Seachem product you're suggesting, though I am skeptical of products like this. I don't get what it does that rock rubble can't? Thank you again for your help!

So my understanding is it just has a lot more surface area for beneficial bacteria to grow. So rather than adding two large rocks you can add a little baggy of it and the beneficial bacteria will grow on it. I think the reason is it’s very porous (similar to pumice) so one bag can equal two to three large rocks in the tank. I am not 100% sure how it works but without changing anything else within a week my Nitrates Stabilized after adding it even after I struggled to get them down.

 

[Miami Reef]

would you think the benefit of carbon dosing (for feeding corals and for reducing nutrients) outweighs any concerns of lowering pH, which for me is already low?

For coralline and coral growth? I think higher pH and alk would have a bigger impact than carbon dosing, which I think could be counterproductive if the cost is reduced pH. But the type coral of coral makes a big difference. Some don’t care or grow faster with elevated pH.

What corals are you referring to when you say “stony?”

This is all currently for a humble 25 gallon, and I have zero problems doing regular water changes to hopefully offset any imbalances.

I see. Well, I think you can predict what I’m going to say. lol

 

[Fish Fan]

So my understanding is it just has a lot more surface area for beneficial bacteria to grow. So rather than adding two large rocks you can add a little baggy of it and the beneficial bacteria will grow on it. I think the reason is it’s very porous (similar to pumice) so one bag can equal two to three large rocks in the tank. I am not 100% sure how it works but without changing anything else within a week my Nitrates Stabilized after adding it even after I struggled to get them down.

I don't doubt your experience, but for denitrification to occur, it needs to be a low to no oxygen environment, and I don't understand how such small pieces of media would achieve that. It could be that I'm missing something for sure.

 

[Fish Fan]

For coralline and coral growth? I think higher pH and alk would have a bigger impact than carbon dosing, which I think could be counterproductive if the cost is reduced pH. But the type coral of coral makes a big difference. Some don’t care or grow faster with elevated pH.

What corals are you referring to when you say “stony?”


I see. Well, I think you can predict what I’m going to say. lol

No, I can't predict what you will say, but I'm all ears

I'm looking to keep things like Pavona, Leptoseris, Stylophora, Seriatopora, etc. I will likely avoid things like Acros for the near future, though I do aspire to a clam or two at some point.

Thank you very much for your help here, I really appreciate it!!

 

[Miami Reef]

No, I can't predict what you will say, but I'm all ears

I'm looking to keep things like Pavona, Leptoseris, Stylophora, Seriatopora, etc. I will likely avoid things like Acros for the near future, though I do aspire to a clam or two at some point.

Thank you very much for your help here, I really appreciate it!!

The corals you mentioned grow like beasts. High pH might increase their growth rate, but those things grow like a menace, regardless.

I’m convinced I could grow them in a toilet. They can’t be killed and spread fast. lol

I say change 50% of your water; it knocks down the NO3 and you can bypass carbon dosing.

But quite frankly, those corals can thrive with NO3 above 100 ppm.

You pretty much have creative liberty here. Carbon dosing is an option. It might lower the pH some, but it’s probably a good thing since you’ll eventually wish they’d stop growing. lol

 

[Miami Reef]

I also don’t see why you can’t add a few acros. I think you’d like pieces like green slimers. Montiporas are great, too.

 

[Randy Holmes-Farley Verified Community Expert]

Vinegar (acetic acid) releases 2 hydrogen ions (H⁺)

The first one immediately when the acetic acid dissociates in water.


The second one later, when bacteria metabolize the acetate and release CO₂, which forms carbonic acid and dissociates.


Ca(OH)₂ (kalkwasser) provides 2 hydroxide ions (OH⁻):

The first OH⁻ neutralizes the initial H⁺, and the second OH⁻ remains available to neutralize the other H⁺ that forms later from CO₂.

@Randy Holmes-Farley can you double check me please?

It’s a little more complicated in saying how much H+ is released, but it does release one H+ instantly and then makes one bicarbonate and one carbonic acid/CO2 after it is metabolized.

 

[Miami Reef]

It’s a little more complicated in saying how much H+ is released, but it does release one H+ instantly and then makes one bicarbonate and one carbonic acid/CO2 after it is metabolized.

Are you saying my explanation was too complicated or is the reality more complicated? I want to be accurate.

 

[Randy Holmes-Farley Verified Community Expert]

Are you saying my explanation was too complicated or is the reality more complicated? I want to be accurate.

Reality is more complicated than the simple idea of 2 H+ released.

Just like it would be complicated to answer: if I add one CO2 molecule to the water, how much H+ is released?

If it stays in the water, some becomes carbonate, releasing 2, some becomes bicarbonate, releasing one. A very small amount stays as carbonic acid, releasing none. And then it may or may not blow back off to the air as CO2, taking the H+ with it. :)

 

[Dr4gula.f32]

I dose AFR and a combination of RODI/Vodka/Vinegar mixture. I noticed the first week that my Alk skyrocketed! I had to dial back the AFR quite a bit. My AFR is dosed 14ml each over 4 periods throughout the day, and the Carbon mixture goes in all at once, 4ml which maintains about 5ppm nitrate.

 

[Sophie"s mom]

^Nice! I'll give the TM products a good look, but glad to know that traditional carbon sources will work, for those of use without a lifetime supply of TM NPBB

For the TM products, I am currently using the Elimi NP, which is designed to lower both, but more so nitrates. Then their idea is once you get things where you want them, you switch to the NP Bacto Balance to keep things stable.

 

[Fish Fan]

For the TM products, I am currently using the Elimi NP, which is designed to lower both, but more so nitrates. Then their idea is once you get things where you want them, you switch to the NP Bacto Balance to keep things stable.

Thank you for your reply! How do you feel the Elimi NP his working for you? This tank is also running high nitrates, but reasonable phosphates.

 

[Sophie"s mom]

Thank you for your reply! How do you feel the Elimi NP his working for you? This tank is also running high nitrates, but reasonable phosphates.

So my numbers were NO3 at 34.5ppm, and PO4 was at .03. So the Elimi NP is doing great. My numbers lastnight were 25.4 nitrate, and .05 phosphate. I have used it in the past and it works great.

 

[Miami Reef]

Reality is more complicated than the simple idea of 2 H+ released.

Just like it would be complicated to answer: if I add one CO2 molecule to the water, how much H+ is released?

If it stays in the water, some becomes carbonate, releasing 2, some becomes bicarbonate, releasing one. A very small amount stays as carbonic acid, releasing none. And then it may or may not blow back off to the air as CO2, taking the H+ with it. :)

Excellent. Thank you.

I thought CO2 mixed with water first caused carbonic acid, then the H popped off to form either carbonate or bicarbonate.

I didn’t think it could bypass the carbonic acid step.

 

[rishma]

Wouldn’t adding kalk to a tank based on AFR not defeat the purpose of AFR without adding additional trace and magnesium based on reduction of AFR now being added due to calcium and alkalinity provided by kalk?

Plus those few frags might not consume that additional kalk therefore not making it more complex than needed which also defeats the purpose of AFR?

Perhaps slow drip the carbon thereby allowing the effects on pH to naturally equalize throughout the day. Keep it simple. Just like the intention behind AFR.

I dose Kalk and AFR. I understand your point, but there are some positives to kalk so I continue to use both. I find using both is reasonable. For someone setting up a new tank, I don’t recommend kalk over AFR but I have not found a detriment to using both.

Kalk helps mitigate the nightly pH drop and the pH drop associated with carbon dosing, if that’s something people want to do. I don’t claim it necessary. It’s cheap, and easy, and you can mix large volumes for use over a long period of time. I have always used kalk, so it’s kinda habit.

I do add a small amount of magnesium every couple of weeks because I cannot always do a monthly water change which would probably handle it.

I like having an independent system to add alkalinity, in case of an issue.

The majority of my alkalinity is provided by AFR and ICP has shown my trace elements stay where I want them.

Anyhow, it works pretty well.

 

[Kasrift]

I am really sorry, in the mix of things above I only now just saw your reply, but I very much appreciate it!

I am using the AquaForrest "reef" salt now, I had been using AF's "sea" salt more recently. Much like Instant Ocean and others, the AF "reef" mix is supposed to mix to higher levels than their "sea" mix. However, I have been testing my newly mixed saltwater, and it's coming up short for alk, which is why I'm so focused on my dosing All For Reef.

My concern is that I'll be overdosing the Alk and Calc (or underdosing Mag and micros) if I am also dosing Kalkwasser along with AFR.

Thank you very much for your reply and for your help!

I like the all at 7.5-8, so it worked for me. For a 25g, I think you'll over complicate things by trying to dose kalk as well. I read all of the literature and thought I needed it too, I gave up trying to figure out a good way to dose it.

As for mag, you are correct. For whatever reason All For Reef is low on that. I typically have to add a 5ml shot of mag midweek to my tank, but I just do it manually with a pippette.

 

[rishma]

Just saw this now. The answer is surprisingly more complicated than expected. I asked Randy the same question 2 years ago.

Short answer: it could be a substantial amount.

https://www.reef2reef.com/threads/h...vinegar-add-to-my-tank.1022991/#post-11996894

Thanks for that link! When I eventually run out of NP BB I will probably make a kalk saturated vinegar dosing solution…maybe with some nitrate and phospate in it too. That will be a fun experiment.

 

[Miami Reef]

Thanks for that link! When I eventually run out of NP BB I will probably make a kalk saturated vinegar dosing solution…maybe with some nitrate and phospate in it too. That will be a fun experiment.

Sounds good! We can’t mix phosphate with Ca(OH)2 because it will precipitate as calcium phosphate.

Everything else is fine.

 

[Fish Fan]

The corals you mentioned grow like beasts. High pH might increase their growth rate, but those things grow like a menace, regardless.

I had hoped to encourage a lot of coralline in this tank, which is said to do better at the higher pH.

I say change 50% of your water; it knocks down the NO3 and you can bypass carbon dosing.

I have done several near 100% water changes, and the nitrates keep coming back. And again, I'm feeding almost nothing to this tank so far.

I also don’t see why you can’t add a few acros. I think you’d like pieces like green slimers. Montiporas are great, too.

I do have a Monti currently, and I believe it's doing well. I did have an Acro stick many years ago that lived, though I don't know if it thrived. I absolutely want to try some, but I want to get a handle on this tank's parameters first.