Nitrates making alk rise

[LxHowler]

So I was speaking to my LFS earlier and they said that my alk could be rising because I have started using nopox to lower nitrates. This sounded odd but what they said kind of made sense and the time frames coinside.
So my nitrates where really high at 40ppm before and my alk was at 9.1. I have now been using nopox and my nitrates are at 5 and my alk is at 9.5.
Is what they said correct or could something else be affecting the alk, I haven't been dosing anything else during this time. I think it would be interesting if now my nitrates are steady my alk starts to drop again.
If this is correct does anyone know why and the science behind it?

 

[andrewey]

In reference to the relationship between nitrate and alkalinity, some great reading is the section alkalinity decline in the nitrogen cycle by RHF:

http://reefkeeping.com/issues/2004-12/rhf/index.htm

As to whether that explains your particular findings, I'll leave to someone else

 

[LxHowler]

In reference to the relationship between nitrate and alkalinity, some great reading is the section alkalinity decline in the nitrogen cycle by RHF:

http://reefkeeping.com/issues/2004-12/rhf/index.htm

As to whether that explains your particular findings, I'll leave to someone else

Thanks for the article, will give me something to read.

 

[Randy Holmes-Farley]

The rise in alkalinity only applies if nitrate is declining, not when it is steady regardless of the level or the use of organic carbon dosing.

 

[LxHowler]

The rise in alkalinity only applies if nitrate is declining, not when it is steady regardless of the level or the use of organic carbon dosing.

So because nopox is carbon based does it mean that it shouldn't change my alk, even though it has dropped my nitrate pretty quickly?

The part where I mentioned it being steady is where it is now, the nitrate has stopped dropping and it has leveled out. I was saying I wanted to see if now that they are steady would my alk start to drop again

 

[Randy Holmes-Farley]

So because nopox is carbon based does it mean that it shouldn't change my alk, even though it has dropped my nitrate pretty quickly?

The part where I mentioned it being steady is where it is now, the nitrate has stopped dropping and it has leveled out. I was saying I wanted to see if now that they are steady would my alk start to drop again

When you produced the nitrate, the alkalinity declined. When you use consumed the nitrate, you got that alkalinity back.

When nitrate is consumed for any reason (e.g., carbon dosing (such as NOPOX, vinegar, etc.) or by macroalgae, etc.) except a sulfur denitrator, alkalinity is produced. About 4.5 dKH for each 50 ppm consumed. Sulfur denitrators deplete alkalinity.

That 4.5 dKH is exactly the amount of alkalinity that was lost when ammonia was converted into 50 ppm of nitrate in the first place.

So any time nitrate is steady, there is no net change to alkalinity from nitrate processes.

Yes, your alk may start to drop again as other organisms use it to deposit calcium carbonate skeletons and shells.

 

[LxHowler]

When you produced the nitrate, the alkalinity declined. When you use consumed the nitrate, you got that alkalinity back.

When nitrate is consumed for any reason (e.g., carbon dosing (such as NOPOX, vinegar, etc.) or by macroalgae, etc.) except a sulfur denitrator, alkalinity is produced. About 4.5 dKH for each 50 ppm consumed. Sulfur denitrators deplete alkalinity.

That 4.5 dKH is exactly the amount of alkalinity that was lost when ammonia was converted into 50 ppm of nitrate in the first place.

So any time nitrate is steady, there is no net change to alkalinity from nitrate processes.

Yes, your alk may start to drop again as other organisms use it to deposit calcium carbonate skeletons and shells.

Thanks for the help. It was confusing me for ages as to why my alk was changing without dosing alk. I look forward to seeing hat happens now everything is stable again

 

[corky1618]

The rise in alkalinity only applies if nitrate is declining, not when it is steady regardless of the level or the use of organic carbon dosing.

Randy, my tank is relatively new (3 months) and my Alk has been steadily increasing from 8.9 to 12.5 over the last few weeks that I started to add some frags. It is a nano tank of about 10-11 gallons and I have made 5 water changes of 25% every time. Every time I measured my new water, the alk is 8.2-8.8, so where is my rise in alk coming from? I have kept a good log of the last 3 weeks and nitrate is zero and phosphate is ranging from .02-.04. Calcium is 420-500. I had a salinity problem because my ATO needed several adjustment before I finally able to get it to work right. All this time, my blastos have no problem but my frogspawn, duncan, and hammer are not liking it at all. I have also used the acclimation features of my kessil starting at 25% and ramping up 7 days. The only parameter that is somewhat out of the ordinary is the alk. I am only feeding my corals a little reef roids and mysis once per week but no dosing of any chemicals.

 

[Randy Holmes-Farley]

Artificial rock that is not fully cured can cause alk to rise. Do you have anything like that? Do you too off with tap water?

Randy, my tank is relatively new (3 months) and my Alk has been steadily increasing from 8.9 to 12.5 over the last few weeks that I started to add some frags. It is a nano tank of about 10-11 gallons and I have made 5 water changes of 25% every time. Every time I measured my new water, the alk is 8.2-8.8, so where is my rise in alk coming from? I have kept a good log of the last 3 weeks and nitrate is zero and phosphate is ranging from .02-.04. Calcium is 420-500. I had a salinity problem because my ATO needed several adjustment before I finally able to get it to work right. All this time, my blastos have no problem but my frogspawn, duncan, and hammer are not liking it at all. I have also used the acclimation features of my kessil starting at 25% and ramping up 7 days. The only parameter that is somewhat out of the ordinary is the alk. I am only feeding my corals a little reef roids and mysis once per week but no dosing of any chemicals.

 

[corky1618]

Artificial rock that is not fully cured can cause alk to rise. Do you have anything like that? Do you too off with tap water?

Thank you for the reply Randy Holmes-Farley, I have read that man made rocks can do that but mine were dried rock but are not man made, they were real live rock(12 lbs) that was dried out. I have broke some of the pieces to aquascape and it is not man made. I did cure them for 2 months prior to actually putting it into the tank and measuring ammonia, nitrite, and nitrate to see it cycle. I am using RO/DI water and measure it and found it to be zero to one tds.