what ways of lowering nitrate

[TheLastKon]

1.5 cups of shrimp =
12 ounces of shrimp =
340 grams of shrimp =
119 grams of food, dry weight (35%) =
100 grams of protein (84%) =
16 grams of nitrogen =
13,122 mg ammonia =
47,771 mg nitrate

In a 681 liter (180 gallon) tank, yields 47771/681 = 70 ppm nitrate every day which is around 7x what your WC schedule and nitrate readings suggest (assuming you are doing huge changes.)

Also, based on your post, I calculated around 6.4 lbs of fish in the tank. So that works out to .68 lbs food/6.4 lbs fish per day, or 11% of net body weight, which is around 4-5x what they should be getting in food per day.


It's like both numbers are off by 5-7x. Maybe you meant per week not per day. That would make more mathematical sense.

Nope. Fed that much daily. Weekly wc for about 6-8 months and then I got tired of dealing with such a high bioload and got rid of the aros, gars, and a few bichirs. Now my water is clean for at least 3 weeks before I notice any changes in the parameters. But I still change once every week or two to make sure I don’t run into problems.

As far as the math is concerned...there’s probably factors that I haven’t noticed that keep my numbers lower than what would be expected from a mathmatical standpoint. I’m not sure 100% what those factors may be but I can tell you that for at least 6 months my water never went above
0.50ppm ammonia
0.50ppm nitrite
10ppm-20ppm nitrate.

I tested once every week or two before my water changes. Added declorinator and salt. No prime or anything to help reduce those numbers. And my water changes ranged from 50-70% depending on how bad my water was.

Just before I got rid of the fish the water parameters were close to the 20ppm. Nitrate range and that’s when I decided I couldn’t keep up anymore. I was doing 2 wc a week for The last 2-3 weeks trying To keep nitrates lower than 10ppm. Finally had enough and decided to get rid of bioload.

 

[tarheel96]

Nope. Fed that much daily. Weekly wc for about 6-8 months and then I got tired of dealing with such a high bioload and got rid of the aros, gars, and a few bichirs. Now my water is clean for at least 3 weeks before I notice any changes in the parameters. But I still change once every week or two to make sure I don’t run into problems.

As far as the math is concerned...there’s probably factors that I haven’t noticed that keep my numbers lower than what would be expected from a mathmatical standpoint. I’m not sure 100% what those factors may be but I can tell you that for at least 6 months my water never went above
0.50ppm ammonia
0.50ppm nitrite
10ppm-20ppm nitrate.

I tested once every week or two before my water changes. Added declorinator and salt. No prime or anything to help reduce those numbers. And my water changes ranged from 50-70% depending on how bad my water was.

Just before I got rid of the fish the water parameters were close to the 20ppm. Nitrate range and that’s when I decided I couldn’t keep up anymore. I was doing 2 wc a week for The last 2-3 weeks trying To keep nitrates lower than 10ppm. Finally had enough and decided to get rid of bioload.

What kind of test kit were you using? Some kits measure nitrate-nitrogen (NO3-N) instead of nitrate (NO3) so you have to multiply the result by 4.42.

Drstrangelove - I get 104 ppm daily NO3 accumulation because of the conversion from nitrogen to ammonia. I'm thinking that you start with 16 grams nitrogen. Hydrogen are added to each nitrogen to form ammonia so the total mass ends up being greater than 16 or 16 x 1.2193?

 

[Drstrangelove]

What kind of test kit were you using? Some kits measure nitrate-nitrogen (NO3-N) instead of nitrate (NO3) so you have to multiply the result by 4.42.

Drstrangelove - I get 104 ppm daily NO3 accumulation because of the conversion from nitrogen to ammonia. I'm thinking that you start with 16 grams nitrogen. Hydrogen are added to each nitrogen to form ammonia so the total mass ends up being greater than 16 or 16 x 1.2193?

This is what I use:

1) Nitrogen has a relative atomic mass of 14.00643, hydrogen is 1.00784, oxygen is 15.999
2) Ammonia is NH4, so total mass of 18.03779; nitrite is NO2, so 46.00443; and nitrate is NO3, so 62.00343.

Protein varies (due to it's amino acid components) but approximates 16% nitrogen.

Not all nitrogen is converted into ammonia. I've seen it stated as 82% which I interpret as 100 grams of nitrogen will become the equivalent of 82 grams of ammonia. This would imply that 64% of the nitrogen combines with hydrogen to form ammonia, with the remaining 36% gassed off or consumed in other biological processes.

Keep in mind, I am a controller not a chemist, so don't quote me.

 

[TheLastKon]

What kind of test kit were you using? Some kits measure nitrate-nitrogen (NO3-N) instead of nitrate (NO3) so you have to multiply the result by 4.42.

Drstrangelove - I get 104 ppm daily NO3 accumulation because of the conversion from nitrogen to ammonia. I'm thinking that you start with 16 grams nitrogen. Hydrogen are added to each nitrogen to form ammonia so the total mass ends up being greater than 16 or 16 x 1.2193?

I use api master freshwater test kit.

 

[Drstrangelove]

Nope. Fed that much daily. Weekly wc for about 6-8 months and then I got tired of dealing with such a high bioload and got rid of the aros, gars, and a few bichirs. Now my water is clean for at least 3 weeks before I notice any changes in the parameters. But I still change once every week or two to make sure I don’t run into problems.

As far as the math is concerned...there’s probably factors that I haven’t noticed that keep my numbers lower than what would be expected from a mathmatical standpoint. I’m not sure 100% what those factors may be but I can tell you that for at least 6 months my water never went above
0.50ppm ammonia
0.50ppm nitrite
10ppm-20ppm nitrate.

I tested once every week or two before my water changes. Added declorinator and salt. No prime or anything to help reduce those numbers. And my water changes ranged from 50-70% depending on how bad my water was.

Just before I got rid of the fish the water parameters were close to the 20ppm. Nitrate range and that’s when I decided I couldn’t keep up anymore. I was doing 2 wc a week for The last 2-3 weeks trying To keep nitrates lower than 10ppm. Finally had enough and decided to get rid of bioload.

The issue of course is that this implies much more:

1) 3/4 pound shrimp per day equates to 8.14 pounds of net dry weight food per month (12 oz * 35% * 31 day.) Typically fish have extremely low feed conversion ratios (FCR) normally in the range of 1-2
https://en.wikipedia.org/wiki/Feed_conversion_ratio
http://www.aqua-techna.com/en/productivity/experts/feed-conversion-ratio-farmed-fish
http://ag.auburn.edu/fish/international/uganda/docs/catfish manualchapters/Chapter6_Feeds and Feeding the Fish.pdf

2) Had the fish biomass been 2.3 pounds at the start of the last 31 days In the 6-8 months reported, then they would have needed to add 4.5 pounds of biomass in the last 31 days. 8.14 pounds of food for 4.5 pounds of growth is an FCR of 1.8. That FCR works fine for what is typically reported. And it works fine if one assumes the larger fish grew several inches (the smaller ones grew 1-2 inches) in the last 31 days.

3) But that feeding regimen runs into a brick wall prior to that when the fish were necessarily much smaller. Even if they doubled in mass (from 1 to 2 pounds) in the prior month, the metrics suggest that the feeding was far lower, since feeding 8 pounds to get 1 pound of growth, or an FCR of 8.0, makes no sense. FCRs don't do that. That, is they don't rapidly decline as the animal gets much larger.

So without having specific data by day or week, this sort of suggests that the feeding of 3/4 pound of shrimp was done only in a tiny part of the 6-8 months, coinciding (and probably not coincidentally) with an increase in water changes. Certainly then, it's plausible that at much lower food levels, the tank was at 20 ppm or less. It would make perfect sense as the fish were far smaller. Not in the last 3-4 weeks though.

 

[tarheel96]

This is what I use:

1) Nitrogen has a relative atomic mass of 14.00643, hydrogen is 1.00784, oxygen is 15.999
2) Ammonia is NH4, so total mass of 18.03779; nitrite is NO2, so 46.00443; and nitrate is NO3, so 62.00343.

Protein varies (due to it's amino acid components) but approximates 16% nitrogen.

Not all nitrogen is converted into ammonia. I've seen it stated as 82% which I interpret as 100 grams of nitrogen will become the equivalent of 82 grams of ammonia. This would imply that 64% of the nitrogen combines with hydrogen to form ammonia, with the remaining 36% gassed off or consumed in other biological processes.

Keep in mind, I am a controller not a chemist, so don't quote me.

Right. Using the atomic masses of N and H, N is equal to 82.35% the mass of NH3 which is where 82% comes from, and if NH3 = N * .8235 it would imply that not all nitrogen would bond with hydrogen in the formation of ammonia, as you say.

Chemistry definitely isn't my forte either but the link below might explain this briefly.

https://www.hamzasreef.com/Contents/Calculators/NitrogenIonConversion.php

Ammonia-nitrogen is a measure of the nitrogen atoms only within the ammonia. I believe N can be substituted in the equations below for NH3-N (or NH4-N) because they are the same thing for this purpose.

NH3 = NH3-N * 1.21589
NH4 = NH4-N * 1.28786

Of course, the amount of nitrogen that goes into the formation of ammonia could be different than the amount of nitrogen in ammonia (once it has already formed) ... I really don't know.

 

[tarheel96]

I use api master freshwater test kit.

I would make sure you're shaking nitrate solution #2 like crazy for the full 2 minutes. API nitrate kit gives low readings. While shaking it, grab the bottle by the cap and knock the bottom edges on a hard surface and then go back to shaking the bottle. Shake solution #2 for at least 2 minutes. Then, as the directions say, wait a full 5 minutes for the color to develop in the test tube before matching it to the chart.

What's your current stocking?

 

[TheLastKon]

I would make sure you're shaking nitrate solution #2 like crazy for the full 2 minutes. API nitrate kit gives low readings. While shaking it, grab the bottle by the cap and knock the bottom edges on a hard surface and then go back to shaking the bottle. Shake solution #2 for at least 2 minutes. Then, as the directions say, wait a full 5 minutes for the color to develop in the test tube before matching it to the chart.

What's your current stocking?

Thread isn’t about my tank. I don’t have any questions about my water quality. And as for my current stock I have 25+ Vieja ranging from 3-8 inches and 5 bichirs ranging from 7-16 inches 4 geos at 4 inches fire eel 14 inch and irwini catfish at 6 inches. Again I have no problems with my tank and am not asking for advice. I am merely saying that I overstock my tanks and have less filtration (compared to his tank and stock) and still have much less waste than that of the original poster.

I will make sure I shake the bottle next time I test my waters. I was unaware that api would give lower readings. What test kit would you suggest?

 

[tarheel96]

I understand. API is a good kit. I use it and recommend it. The nitrate test is the only one that gives problems and nitrate solution #2 is the only solution that needs shaking. It just needs to be shaken beyond what most would consider reasonable ... especially when the bottle is mostly full. It you know that then it's a great kit. No other solution in the API kit needs shaking.

I have some individual Salifert and Seachem kits which are both very good. I like the Salifert especially but for the price I believe API is the best. Red Sea is very good but it's expensive.

 

[Drstrangelove]

Right. Using the atomic masses of N and H, N is equal to 82.35% the mass of NH3 which is where 82% comes from, and if NH3 = N * .8235 it would imply that not all nitrogen would bond with hydrogen in the formation of ammonia, as you say.

Chemistry definitely isn't my forte either but the link below might explain this briefly.

https://www.hamzasreef.com/Contents/Calculators/NitrogenIonConversion.php

Ammonia-nitrogen is a measure of the nitrogen atoms only within the ammonia. I believe N can be substituted in the equations below for NH3-N (or NH4-N) because they are the same thing for this purpose.

NH3 = NH3-N * 1.21589
NH4 = NH4-N * 1.28786

Of course, the amount of nitrogen that goes into the formation of ammonia could be different than the amount of nitrogen in ammonia (once it has already formed) ... I really don't know.

I see what you did. Nice!

Yes, I was unsuccessfully attempting to calculate the 82% using ammonium (NH4), which I think would be useful only at low pH levels.