george9
Active Member
Hi everyone,
I have a 40gallon FOWLR I’ve been running for a few months now and haven’t had nitrate issues per se, but they do run upwards of 25PPM at times which is a bit higher than I’d like. My water changes have kept them around this range, but I would notice that even after a water change, NO3 would increase at a rate that was just strange sometimes. I did a 30% water change a couple days ago and got the NO3 down to between 5-10PPM but today it’s already looking around 10-15PPM 2 days later which is fishy to me. So I decided to crunch some numbers based on my phyto dosing to see if this was the culprit. I really had no clue how much NO3 could possibly be in this stuff.
I have been dosing 20-30mL (super approximate) of Phyto each day to the tank. I just received a new bottle today and made a solution of 1 part phyto and 9 parts clean seawater. So, this was 10ML phyto and 90mL clean seawater (with 0PPM nitrate). So we can ensure any NO3 in my solution is coming from the phyto. This dilution makes a clear solution that I can actually run a nitrate test on so the green tint of the phyto doesn’t skew the color of the test result
The resultant NO3 of the 1:10 solution was around 20PPM!! This means that in pure phyto and no seawater, the [NO3] is approximately 10 * 20PPM which is 200PPM of No3 in 10mL from the phytoplankton bottle. There must be some insane fertilizers in this stuff, but I am not sure because I do not culture my own phyto.
Okay. Now let’s say 20mL of phyto a day added to a 35g system (accounting for rocks and sand) would mean I am adding .00528gal (which is 20mL converted to gallons) of phytoplankton with a subsequent 200PPM nitrate concentration to a 35g volume tank with let’s say a NO3 concentration of 10PPM.
taking the ratio of these volumes:
.00528gal / 35gal = .00015
in percentage: .00015 * 100% = .015%
This means I am adding .015% of the tank volume daily in phyto (which contains 200PPM NO3).
Let’s do the calculation to see what that will bring the 10PPM existing NO3 in the tank up to with each daily dose.
.015% of a 200PPM solution mixed with 98.5% of a 10PPM solution:
.015 (200ppm) + .985 (10ppm) = 12.85PPM NO3 in the tank after the phyto addition.
Could I really possibly be dosing 2.85PPM of NO3 with each 20ML dose of phyto? Or is my math askew somewhere?
I tested my old bottle of phyto and it had about half as much nitrates as this new one, but it was about a month and a half old. Either way, this would add over 1PPM of no3 daily to the tank anyways. Still too high for me given this is NOT a nitrogen limited tank lol
We can likely safely assume the NO3 is variable between bottles and sources of phyto but man, this is significantly higher than I thought it would ever be. Curious to hear any thoughts.
Thanks for reviewing!
I have a 40gallon FOWLR I’ve been running for a few months now and haven’t had nitrate issues per se, but they do run upwards of 25PPM at times which is a bit higher than I’d like. My water changes have kept them around this range, but I would notice that even after a water change, NO3 would increase at a rate that was just strange sometimes. I did a 30% water change a couple days ago and got the NO3 down to between 5-10PPM but today it’s already looking around 10-15PPM 2 days later which is fishy to me. So I decided to crunch some numbers based on my phyto dosing to see if this was the culprit. I really had no clue how much NO3 could possibly be in this stuff.
I have been dosing 20-30mL (super approximate) of Phyto each day to the tank. I just received a new bottle today and made a solution of 1 part phyto and 9 parts clean seawater. So, this was 10ML phyto and 90mL clean seawater (with 0PPM nitrate). So we can ensure any NO3 in my solution is coming from the phyto. This dilution makes a clear solution that I can actually run a nitrate test on so the green tint of the phyto doesn’t skew the color of the test result
The resultant NO3 of the 1:10 solution was around 20PPM!! This means that in pure phyto and no seawater, the [NO3] is approximately 10 * 20PPM which is 200PPM of No3 in 10mL from the phytoplankton bottle. There must be some insane fertilizers in this stuff, but I am not sure because I do not culture my own phyto.
Okay. Now let’s say 20mL of phyto a day added to a 35g system (accounting for rocks and sand) would mean I am adding .00528gal (which is 20mL converted to gallons) of phytoplankton with a subsequent 200PPM nitrate concentration to a 35g volume tank with let’s say a NO3 concentration of 10PPM.
taking the ratio of these volumes:
.00528gal / 35gal = .00015
in percentage: .00015 * 100% = .015%
This means I am adding .015% of the tank volume daily in phyto (which contains 200PPM NO3).
Let’s do the calculation to see what that will bring the 10PPM existing NO3 in the tank up to with each daily dose.
.015% of a 200PPM solution mixed with 98.5% of a 10PPM solution:
.015 (200ppm) + .985 (10ppm) = 12.85PPM NO3 in the tank after the phyto addition.
Could I really possibly be dosing 2.85PPM of NO3 with each 20ML dose of phyto? Or is my math askew somewhere?
I tested my old bottle of phyto and it had about half as much nitrates as this new one, but it was about a month and a half old. Either way, this would add over 1PPM of no3 daily to the tank anyways. Still too high for me given this is NOT a nitrogen limited tank lol
We can likely safely assume the NO3 is variable between bottles and sources of phyto but man, this is significantly higher than I thought it would ever be. Curious to hear any thoughts.
Thanks for reviewing!
