Alkalinity for the Chemistry Challenged Reefer

[A_Blind_Reefer]

Does dosing ammonia lower alkalinity?

Interesting is that I recently started dosing ammonia (I’ve been dosing sodium nitrate for a few years now) and my initial results are that as I’m adding .2 ppm ammonia per day, my nitrate has gone up by .7 ppm per day, and my alkalinity has gone up by .7 dkh per day. Not scientific in anyway, or proof of anything, just my initial readings on my system which for sure isn’t anything to speak of. I’m only a couple weeks in.

 

[DrTim]

Dosing ammonia lowers the alkalinity because both the oxidation of ammonia to nitrite and nitrite to nitrate produces hydrogen ions (H+). The H+ ions are neutralized by the alkalinity until the alkalinity drops to zero then your pH will fall. "The oxidation of 1 milligram of ammonium ions destroys 7.14 mg of alkalinity (measured as CaCo3)."

 

[Randy Holmes-Farley Verified Community Expert]

Dosing ammonia lowers the alkalinity because both the oxidation of ammonia to nitrite and nitrite to nitrate produces hydrogen ions (H+). The H+ ions are neutralized by the alkalinity until the alkalinity drops to zero then your pH will fall. "The oxidation of 1 milligram of ammonium ions destroys 7.14 mg of alkalinity (measured as CaCo3)."

I do not agree that it is that simple, and you are focusing on cycling, not an operating reef tank.

`First, when folks say they are dosing ammonia, it can mean many different things being dosed, such as ammonium chloride, ammonium bicarbonate (both recipes are in my DIY thread for ammonia dosing), or ammonium hydroxide.

Those have very different alkalinity effects. No matter what else happens, dosing ammonium chloride will add less alk or reduce alk more than ammonium hydroxide or ammonium bicarbonate.

If nitrate is rising for any reason, independent of whether you are dosing ammonia, that conversion depletes alkalinity, which is the process you note. Each 50 ppm rise in nitrate depletes 2.3 dKH of alk.

If nitrate is stable, the ammonia/nitrate processes do not have any net effect on alk.

If nitrate is falling, that process adds alkalinity (unless it is only falling due to water changes).

Now, in an operating reef tank where dosed ammonia is being used as an N source for tissue growth, the conversion of NH3 to organic tissue has no impact on alkalinity. So if you dose the equivalent of NH3 (as ammonium hydroxide which is NH3 dissolved in water, such as household ammonia) or ammonium bicarbonate (which is NH3 plus CO2 + water) then the effect is as I note here: no effect on alkalinity.

OTOH, in an operating reef tank where dosed ammonium chloride (NH3 + HCl) is being used as an N source for tissue growth, the conversion of NH3 to organic tissue has no impact on alkalinity, but the dosed HCl is depleting alkalinity. So if you dose the equivalent of NH3 + HCl (as ammonium chloride) then the effect is to deplete alkalinity.

For those interested, this is the ammonia dosing thread for low nitrate systems, including recipes:

DIY Ammonia dosing for low nitrate systems

Some reef aquaria have chronic low nitrogen availability. One indicator is very low nitrate. Nitrate dosing is a fine remedy, but it is possible that ammonia dosing may be more beneficial for some organisms since ammonia can be energetically easier to assimilate than is nitrate. For this...

www.reef2reef.com

 

[Doctorgori]

I'd also add a number 6; higher alkalinity can lead to faster calcification (skeletal growth) of many hard corals. The reason for #5 is presumably because the coral needs more nutrients to keep the tissue growing fast enough to cover faster growing skeletons of some corals, or risk getting 'burnt tips' which may be too thin of tissue on coral growing tips.

Thank you, I’ve always wondered “exactly” why I had issues using high level salts like RC and Fritz red, or Alk in the 11-ish .

I went over numerous threads especially those touting NSW levels for everything and finally settled on playing it safe with 8ish -9ish dKH …

Not saying thats ideal, but would rather love to see a “All-in-one” discussion/debate on how to run higher alkalinity successfully and if so, why?

 

[Randy Holmes-Farley Verified Community Expert]

Thank you, I’ve always wondered “exactly” why I had issues using high level salts like RC and Fritz red, or Alk in the 11-ish .

I went over numerous threads especially those touting NSW levels for everything and finally settled on playing it safe with 8ish -9ish dKH …

Not saying thats ideal, but would rather love to see a “All-in-one” discussion/debate on how to run higher alkalinity successfully and if so, why?

IMO, the how and why of higher alk are (copied from an article of mine):

Interestingly, because some corals may calcify faster at higher alkalinity levels, and because the abiotic (nonbiological) precipitation of calcium carbonate on heaters and pumps also rises as alkalinity rises, the demand for alkalinity (and calcium) rises as the alkalinity rises. So an aquarist generally must dose more calcium and alkalinity EVERY DAY to maintain a higher alkalinity (say, 11 dKH) than to maintain 7 dKH. It is not just a one-time boost that is needed to make up that difference. In fact, calcification gets so slow as the alkalinity drops below 6 dKH that reef aquaria rarely get much below that point, even with no dosing: natural calcification has nearly stopped at that level.

In general, I suggest that aquarists maintain alkalinity between about 7-11 dKH (2.5 and 4 meq/L; 125-200 ppm CaCO3 equivalents). Many aquarists growing SPS corals and using Ultra Low Nutrient Systems (ULNS) have found that the corals suffer from "burnt tips" if the alkalinity is too high or changes too much. It is not at all clear why this is the case, but such aquaria are better served by alkalinity in the 7-8 dKH range. One possible explanation is that coral skeletal growth takes place faster than tissue growth can keep up at high alk/low nutrients.

As mentioned above, alkalinity levels above those in natural seawater increase the abiotic precipitation of calcium carbonate on warm objects such as heaters and pump impellers, or sometimes even in sand beds. This precipitation not only wastes calcium and alkalinity that aquarists are carefully adding, but it also increases equipment maintenance requirements and can damage a sand bed, hardening it into a chunk of limestone. When elevated alkalinity is driving this precipitation, it can also depress the calcium level. An excessively high alkalinity level can therefore create undesirable consequences.

 

[lmfbs]

This thread is perfect for all my silly alk related questions, perhaps!

My approach, to help make myself feel a bit less overwhelmed, and because I know there's an interaction between alk and calc, is that I'm currently focusing on getting my alk stable and where I want it (I'm a few weeks into this, I've needed to raise my alk from low 7s, and I'm aiming for a consistent ~8.6. I'm wary of raising the dKH too much too quickly.

My plan is to:

1. focus on getting my alk up and stable on a day to day/week to week basis via dosing
2. once alk is stable for a couple of weeks, I'll target calcium consistency via dosing (aiming for ~450 in lieu of a reason not to)
3. Once calcium is stable, I'll focus on mag consistency via dosing (aiming for ~1400).

While I'm focusing on alk, I've been testing calcium and mag weekly-ish to make sure they don't get too far away from where they should be.

My rationale for this approach is I understand alkalinity consistency is more stressful for corals than calcium and magnesium consistency, because alk and calc impact each other, and because I feel like if I focus on a bunch of things, I'm more likely to create more instability. My pH is pretty stable at 8.3 - 8.5 (if I test consistently at the same time each day).

Questions:

1. is 8.6 dkh for a pretty new, pretty low stocked tank with softies and LPS primarily a good target? I'm planning to have primarily an LPS tank, and my tank is currently growing coralline like crazy and using ~0.7 - 1 dKH a day.
2. Is my staged plan stupid? Will I regret this choice?
3. Would you recommend a different plan?
4. Is it true the best time to test alk is before the lights go on? If I test consistently at the same time in the evening when the lights are on, what do I need to be concerned about?

Edit: I can't believe I forgot to say thank you in advance for your time, smart friends.

 

[Randy Holmes-Farley Verified Community Expert]

This thread is perfect for all my silly alk related questions, perhaps!

My approach, to help make myself feel a bit less overwhelmed, and because I know there's an interaction between alk and calc, is that I'm currently focusing on getting my alk stable and where I want it (I'm a few weeks into this, I've needed to raise my alk from low 7s, and I'm aiming for a consistent ~8.6. I'm wary of raising the dKH too much too quickly.

My plan is to:

1. focus on getting my alk up and stable on a day to day/week to week basis via dosing
2. once alk is stable for a couple of weeks, I'll target calcium consistency via dosing (aiming for ~450 in lieu of a reason not to)
3. Once calcium is stable, I'll focus on mag consistency via dosing (aiming for ~1400).

While I'm focusing on alk, I've been testing calcium and mag weekly-ish to make sure they don't get too far away from where they should be.

My rationale for this approach is I understand alkalinity consistency is more stressful for corals than calcium and magnesium consistency, because alk and calc impact each other, and because I feel like if I focus on a bunch of things, I'm more likely to create more instability. My pH is pretty stable at 8.3 - 8.5 (if I test consistently at the same time each day).

Questions:

1. is 8.6 dkh for a pretty new, pretty low stocked tank with softies and LPS primarily a good target? I'm planning to have primarily an LPS tank, and my tank is currently growing coralline like crazy and using ~0.7 - 1 dKH a day.
2. Is my staged plan stupid? Will I regret this choice?
3. Would you recommend a different plan?
4. Is it true the best time to test alk is before the lights go on? If I test consistently at the same time in the evening when the lights are on, what do I need to be concerned about?

Edit: I can't believe I forgot to say thank you in advance for your time, smart friends.

#1 is fine, but so is 7 dKH and 10 dKH. Alk is really a matter of choice for the types of corals you have, and what matters most (higher alk can yield faster growth of some hard corals).

#2 is fine. Magnesium depletion, if any, is very slow. It never needs to be added daily.

#4 is not true, and evening testing is fine.. Without dosing, alk generally trends downward only, except in some unusual circumstances. It does not cycle up and down, unelss your dosing is causing the cycling.