Alkalinity and nitrification...

[reverendmaynard]

Hi Randy,

I've read a lot of your articles about alkalinity and supplementation using 2 parts (i use your recipe #1), and most of them stress balanced additions, in the ratios in which they are used by calcification. I don't recall seeing much mention of the role alk plays in the nitirification process. I'm wondering if you can share your thoughts on this, or point me to an article.

Isn't carbonate alkalinity a primary source of carbon for the nitirification process? Couldn't that significantly skew the "balance" of the addition of 2 part additives?

The reason I ask is that I don't currently have any calcifying corals, so the primary calcifiers in my tank would be coralline algae, and maybe snails, and my demands for calcification should be fairly low. I find that I am adding about twice as much alk as calc to keep the levels in balance, and even then they seem to get skewed towards high calc and low alk. I know some of it has to do with my salt (oceanic) being skewed in those directions, but it doesn't seem like weekly 10-15% wcs would skew the ratio that far.

Any thoughts?

 

[Randy Holmes-Farley]

Nitrification does use alkalinity, and denitrification gives it back. So unless nitrate is increasing (not just high, but actually increasing), the nitrogen cycle has little effect on alkalinity.

This article has more:

When Do Calcium and Alkalinity Demand Not Exactly Balance?
http://reefkeeping.com/issues/2004-12/rhf/index.htm



I know some of it has to do with my salt (oceanic) being skewed in those directions, but it doesn't seem like weekly 10-15% wcs would skew the ratio that far.


That could be big enough to skew it. It is also possible that the mix that you made is skewed for whatever reason. What did you use for calcium in it?

 

[reverendmaynard]

I'm using a pellet form of driveway heat, not one of the brands you tested. I made it based on your recomendation for the prestone driveway heat (I think 2 cups, instead of the 2.5cups of flake.)

My tank is fairly new, and until the last couple of weeks I hadn't seen a noticable decrease in nitrates through water changes (started with nitrates due to using old water that was in the used tank, they stayed between 20-30ppm for the first 8 weeks or so), which would suggest I was getting more nitrification than denitrification. The past couple of weeks it has started to come down (now down to less than 10ppm), I assume as my sand bed and remote DSB in a bucket have started "kicking in". Perhaps my additions will begin to balance out as that process continues, and my wcs decrease.

 

[Randy Holmes-Farley]

The actual amount of calcium in that material will depend on the moisture in it, so it may be going into the mix on the high side.

 

[reverendmaynard]

Is there a simple way to determine the concentration of my solution?

 

[Randy Holmes-Farley]

Not easily. You could estimate it and the alkalinity part with test kits, after dilution, or if you had a calibrated conductivity meter we might be able to determine it that way by comparing to a calcium chloride standard.

 

[reverendmaynard]

Hmmm.... Sounds like a lot of effort. I think I'll just continue with the occasional testing until I get a real good feel for how much needs to be added to maintain levels. I'll also need to test mg, since that should be in a ratio with calcium, and if I don't know the concentration of my calc solution, I don't know how much mg to add. Correct?

Thanks for the help Randy.

 

[Habib]

Perhaps density measurement or refractive index after a simple dilution step (perhaps tenfold or better fivefold) might be options to get a good enough estimation.

Required dilution to be usable with regular aquarium apparatus to measure density or refractive index would depend on the initial concentration of the solutions.

For test kits a much higher dilution would be required making it perhaps less accurate (for hobbyists) than above methods.

 

[reverendmaynard]

Are you saying I can dilute it with DI water, 5:1, and use my refractometer to measure it? What would the readings mean?

 

[Habib]

<a href=showthread.php?s=&postid=6967680#post6967680 target=_blank>Originally posted</a> by reverendmaynard
Are you saying I can dilute it with DI water, 5:1, and use my refractometer to measure it? What would the readings mean?

If you know the composition of the supplements or assume one to be mostly calcium chloride and the other sodium bicarbonate or carbonate then tables (from the literature or with some help) can be used to find with which concentration value the refractive index or density corresponds.

Dilution might be needed to bring the concentration in a range the aquarium hobby instruments can measure.

 

[Randy Holmes-Farley]

Does your refractometer give values in refractive index? Or only units relating to salinity of seawater?

 

[Habib]

<a href=showthread.php?s=&postid=6969589#post6969589 target=_blank>Originally posted</a> by Randy Holmes-Farley
Does your refractometer give values in refractive index? Or only units relating to salinity of seawater?

Are you asking me or Reverend Maynard?

 

[Randy Holmes-Farley]

Rev.

 

[reverendmaynard]

Not sure what you mean, Randy. It has SG (normal reading of 1.025) on one side and ppt (about 34 normally) on the other. Does that answer the question?

 

[Randy Holmes-Farley]

If it read refractive index (which looks like 1.3342), then we could look up the refractive index in a table of the refractive index of calcium chloride solutions (which I have). But translating it into the units on your meter (salinity of seawater) is probably not worth the effort.

 

[reverendmaynard]

Ok. I guess I'm just gonna wing it for now. It seems, with all three of these components more is better, within reason. So I'll just try to overshoot by a little, so if I'm off on the low side, and don't test for a while, it shouldn't reach catastrophically low levels.

Thanks for the help. You too, Habib.

 

[Habib]

<a href=showthread.php?s=&postid=6969771#post6969771 target=_blank>Originally posted</a> by Randy Holmes-Farley
If it read refractive index (which looks like 1.3342), then we could look up the refractive index in a table of the refractive index of calcium chloride solutions (which I have). But translating it into the units on your meter (salinity of seawater) is probably not worth the effort.

CRC has a table for seawater too, including concentrated (IIRC).

salinity reading ---> refractive index from the table ---> calcium concentration from another table.

 

[Randy Holmes-Farley]

I'm just worried that each step introduces more uncertainty.

We can do it, I guess.

rev: if you want, you can see if you get any reading at all with it on your refractometer without diluting it first.

 

[reverendmaynard]

I'll try it tonight when I get home. Undiluted, huh?

 

[Randy Holmes-Farley]

If you can get a reading, yes. I do not know how high your refractometer goes.