Nitrate: You have to read this

dallasg

Controversial Reefer, but knowledgeable!
Moderator
Joined
14 Dec 2008
Posts
16,900
Reaction score
666
Location
Sandton
Once again RHF delves into the grind, brilliant article
Nitrate in the Reef Aquarium - REEFEDITION

Most of the nitrate present in the ocean results from the recycling of organic materials. The degradation of plankton, for example, provides nitrate. This can be shown in a simplified chemical equation describing what happens when organic “food” is digested with oxygen:

(CH2O)106(NH3)16(H3PO4) + 138 O2 → 106 CO2 + 122 H2O + 19 H+ + PO43- + 16 NO3-

which in words reads as:

plankton + oxygen → carbon dioxide + water + hydrogen ion + phosphate + nitrate

Note that this process consumes alkalinity (the H+ being produced shows this). So when nitrate is accumulating in a reef tank, alkalinity is being depleted. Production of 10 ppm of nitrate will deplete about 0.16 meq/L (0.45 dKH) of alkalinity. If this nitrate is removed by water change, that alkalinity is lost forever. If the nitrate is taken up by an organism (algae, coral, bacteria, etc.) and used, then all of that alkalinity is returned to the system (see equations below showing this fact).
 
Do the salt we add have any alkalinity?
Or is it between zero and 0.16 meq/L?
 
Do the salt we add have any alkalinity?
Or is it between zero and 0.16 meq/L?

Production of 10 ppm of nitrate, nitrogen cycle, will deplete about 0.16 meq/L (0.45 dKH) of alkalinity, so what he is saying is that if you WC to remove nitrate you wasting alk, but if you doing 10% WC is that factor adding more or removing 0.16meq/L
 
Do the salt we add have any alkalinity?

Salt does to the correct required parameters or specified parameters, but if you're losing the Alk by pulling it out, it will need to be replaced eventually, cause as it gets taken out via the WC you need to supplement it in again, if you are not dosing.
 
so running a DSB is better?

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.

So there is no depletion. Sticking to the same brand of salt would then also keep alkalinity at around the same value.
 
Do you not add water with alk of roughly 12 dKH when using good coral salt, Tropic Marine Reef Pro shows it has an alk of 12 dKH. So by adding higher alk concentration water you are removing nitrates and adding back alk or am I missing something? For instance my setup runs at alk of 7 naturally. It is 72L, if I remove 15% (+-10L water) of 7dKH and replace with 10L of 12 dKH I should have (62x7+10x12)/72=7.7dKH new water, do not know if this is a valid calc but that is what my logic tells me. So if I lose 0.45dKH by 10ppm nitrogen cycle I should replace more (0.7) at next w/c.
 
Do you not add water with alk of roughly 12 dKH when using good coral salt, Tropic Marine Reef Pro shows it has an alk of 12 dKH. So by adding higher alk concentration water you are removing nitrates and adding back alk or am I missing something? For instance my setup runs at alk of 7 naturally. It is 72L, if I remove 15% (+-10L water) of 7dKH and replace with 10L of 12 dKH I should have (62x7+10x12)/72=7.7dKH new water, do not know if this is a valid calc but that is what my logic tells me. So if I lose 0.45dKH by 10ppm nitrogen cycle I should replace more (0.7) at next w/c.

so how did you lose the initial 5 dKH?
 
So there is no depletion. Sticking to the same brand of salt would then also keep alkalinity at around the same value.

there would be a decrease if you are not dosing alk and doing water changes, this is if I'm reading correctly..

Coral consumes alk, so you'd be dosing that anyways.
 
I'm not dosing anything, but then again I got a softy dominated system. Nitrate at .1
Just doing water changes when I get time.
 
soft corals, and hard will consume NO3 as mentioned...
way back when i never used a skimmer, i used corals as filters :)
 
Nice article, thanks Dal. @RiaanP, time to venture out into sps, or too scared? Don't tell us you have no time.
 
Last edited by a moderator:
ja ja...
One day, when I'm not that often away from home.
 
I know.
but work is work.
And I have to be realistic. Need a system that can look after himself. Tank sitter only needs to feed the fish. That is it. Tank can run for 2 weeks with no other tasks needed.
So until I have another job, my system will stay as is.
 
so how did you lose the initial 5 dKH?

Must have been used up by the corals, I have some SPS and LPS. ATM I alk seems to stay up with only water changes but will probably have to start dosing alk as I get more growth and corals. This is a very interesting article but since my tank does not have the capacity to deal with the nitrates water changes is my only option.
 
alk should be dosed on a daily basis at least a weekly basis with your Ca and Mg. Mg stabilizes the CA and Alk levels so the levels can be elevated to the required Alk and Ca parameters essential for Coral growth. Do water changes; and according to the article you lose more alk. You tried any sort of source for Carbon dosing to keep your nutrient levels within spec? Nutrient levels are prolly the only reason why you do water changes for the moment?
@Franske
 
Last edited by a moderator:
Do water changes; and according to the article you lose more alk
Back to my question.

What happens if the new salt water alkalinity is higher than 0.16 meq/L?
Plus the water change add Ca and MG. As long as its higher than your tank at that moment. OK, that depends on the salt, "cheaper" salt meant for fish only systems will not have enough Ca or Mg. Salt marketed as Coral Pro or special should have high enough levels to replenish what was used.

Very well to take part of the article. But that is not the full picture applicable to everyone's tank. Each tank is different. There are many brands of salt out there. And different setups.

I do not say that my method is the right way. But it works for me. I do not dose anything. I do not do my 10% water change every week, more like every second week or so. But my corals are growing.

These two photo's are 6 months apart.

07-08-2014
Centurion-20140807-00676_zps25ee316e.jpg


14-01-2015
Centurion-20150114-00130_zpsf08dd588.jpg


Tell my corals to stop growing... I'm running out of space an need to upgrade.

Note the small pincushion on the left. And the anemone below it.
 
you missing the point, by doing 10% water change, to remove NO3 you are loosing a possible 0.16meq/L of ALK which is more costly than theNO3. You are better off using another means of nutrient control and allowing corals & algae to re-use the NO3 to produce the alk from the H+ ion.
 
Last edited:
Back
Top Bottom