Hello SeaChem;
This is from the "I have Done the Experiments and it May Interest You to Know" department, but there is a question here.
This is a question posed out of scientific curiosity only. I am not troubleshooting. However, my understanding on this subject is not complete, and I would really appreciate your feedback.
I am running a high light/high tech 200 gallon jungle style planted aquarium. I monitor O2 tension (DO) and ORP continuously. Along with lots of other things, there are five large and thriving Echinodorus swordplants. I auto-dose all supplements daily at first light of dawn. In addition to inorganic salts, I dose the following SeaChem substances:
Flourish Comprehensive
Flourish Advance
Flourish Excel
Flourish Trace
All iron in the water column derives from the ferrous gluconate in Flourish Comprehensive. The dosing pump is calibrated such that Fe, usually tested within two hours of dosing, reads 0.1 to 0.3. I try to stay on the high end of this range, currently dosing 8 ml daily. This is more or less in line with your dose-rate recommendation, bumped up a bit for high-growth conditions (carbon fixation proceeds apace).
Excel and Trace are dosed according to your label directions, adjusted for daily distribution but holding to recommended maximums. Trace and Comprehensive doses are separated by 20 minutes. I dose Advance at 50 ml per day (half of label direction).
Inorganic supplements in use, and dosed at the same time as the above, are:
K2CO3
KNO3/Ca(NO3)2
MgSO4/K2SO4
Orthophosphate derives completely from fish food/environmental metabolism and is not dosed as a supplement. This aquarium is heavily stocked.
At the time of dosing - between 07:00 and 07:30 AM - the following two things occur:
1) The ORP plunges approximately 40 mV over about 45 minutes, then gradually recovers throughout the day, plateauing at maximum overnight. The normal running average redox in this tank is currently circa 500 mV.
2) The DO of course descends overnight, but just before lights ON takes a pronounced dip, about 1 ppm. Photosynthesis begins and drives the DO to saturation by midday. The nadir of this dip corresponds exactly with the redox notch. I have programmed aeration to kick in at 6 ppm O2. The air pump is ON-OFF active for around 3 hours. This compensates the O2 deficit and erases the dip in the DO curve, and also appears to accelerate ORP recovery. This period just after dosing is the only time the air pump ever runs.
Clearly, dosing is adding reduced/reducing chemistry. I have experimented with timing the withholding of doses of the various supplements and discovered the following:
Flourish Comprehensive, Excel, and Advance each contribute significantly to this effect. Individually they are slightly variable from day to day, but always evident. Flourish Trace also causes a small but consistently detectable depression in ORP, which I did not expect to see. The inorganic compounds listed above do not seem to exhibit the effect, but if there is a theoretical reason why any of these salts should do so, I will take a second look.
So I am reviewing the ingredients labels and trying to understand what is happening. Again, I wish to be clear about this; there is nothing amiss going on here. DO in this tank never drops below 5 ppm, environmental metabolism is robust, and the BOD is extremely low. I just want to have a more detailed grasp of the chemistry. I am expecting (out of imperfect knowledge to be sure) that in order to identify substances which are reduced, I would typically - but not necessarily exclusively - be searching for organic molecules. I am seeing gluconate, protein hydrolysates (peptides and amino acids), mannitol, ascorbic acid, and polycyclogluteracetyl; and a lot of anions, especially ferrous iron in quantity (which is suggestive). Flourish Trace appears to be all inorganic salts, mostly sulfates, with no complexing agents (chelates), and does not contain any organic compounds.
I think I can generalize a finding that all the named SeaChem Flourish products, taken together, constitute a veritable cocktail of reduced compounds and metals. That adding them to the water column definitely causes the stated reactions in my instrumentation is observed fact.
Which ingredients are actually causing these reactions in my DO and ORP probes?
Paul G
This is from the "I have Done the Experiments and it May Interest You to Know" department, but there is a question here.
This is a question posed out of scientific curiosity only. I am not troubleshooting. However, my understanding on this subject is not complete, and I would really appreciate your feedback.
I am running a high light/high tech 200 gallon jungle style planted aquarium. I monitor O2 tension (DO) and ORP continuously. Along with lots of other things, there are five large and thriving Echinodorus swordplants. I auto-dose all supplements daily at first light of dawn. In addition to inorganic salts, I dose the following SeaChem substances:
Flourish Comprehensive
Flourish Advance
Flourish Excel
Flourish Trace
All iron in the water column derives from the ferrous gluconate in Flourish Comprehensive. The dosing pump is calibrated such that Fe, usually tested within two hours of dosing, reads 0.1 to 0.3. I try to stay on the high end of this range, currently dosing 8 ml daily. This is more or less in line with your dose-rate recommendation, bumped up a bit for high-growth conditions (carbon fixation proceeds apace).
Excel and Trace are dosed according to your label directions, adjusted for daily distribution but holding to recommended maximums. Trace and Comprehensive doses are separated by 20 minutes. I dose Advance at 50 ml per day (half of label direction).
Inorganic supplements in use, and dosed at the same time as the above, are:
K2CO3
KNO3/Ca(NO3)2
MgSO4/K2SO4
Orthophosphate derives completely from fish food/environmental metabolism and is not dosed as a supplement. This aquarium is heavily stocked.
At the time of dosing - between 07:00 and 07:30 AM - the following two things occur:
1) The ORP plunges approximately 40 mV over about 45 minutes, then gradually recovers throughout the day, plateauing at maximum overnight. The normal running average redox in this tank is currently circa 500 mV.
2) The DO of course descends overnight, but just before lights ON takes a pronounced dip, about 1 ppm. Photosynthesis begins and drives the DO to saturation by midday. The nadir of this dip corresponds exactly with the redox notch. I have programmed aeration to kick in at 6 ppm O2. The air pump is ON-OFF active for around 3 hours. This compensates the O2 deficit and erases the dip in the DO curve, and also appears to accelerate ORP recovery. This period just after dosing is the only time the air pump ever runs.
Clearly, dosing is adding reduced/reducing chemistry. I have experimented with timing the withholding of doses of the various supplements and discovered the following:
Flourish Comprehensive, Excel, and Advance each contribute significantly to this effect. Individually they are slightly variable from day to day, but always evident. Flourish Trace also causes a small but consistently detectable depression in ORP, which I did not expect to see. The inorganic compounds listed above do not seem to exhibit the effect, but if there is a theoretical reason why any of these salts should do so, I will take a second look.
So I am reviewing the ingredients labels and trying to understand what is happening. Again, I wish to be clear about this; there is nothing amiss going on here. DO in this tank never drops below 5 ppm, environmental metabolism is robust, and the BOD is extremely low. I just want to have a more detailed grasp of the chemistry. I am expecting (out of imperfect knowledge to be sure) that in order to identify substances which are reduced, I would typically - but not necessarily exclusively - be searching for organic molecules. I am seeing gluconate, protein hydrolysates (peptides and amino acids), mannitol, ascorbic acid, and polycyclogluteracetyl; and a lot of anions, especially ferrous iron in quantity (which is suggestive). Flourish Trace appears to be all inorganic salts, mostly sulfates, with no complexing agents (chelates), and does not contain any organic compounds.
I think I can generalize a finding that all the named SeaChem Flourish products, taken together, constitute a veritable cocktail of reduced compounds and metals. That adding them to the water column definitely causes the stated reactions in my instrumentation is observed fact.
Which ingredients are actually causing these reactions in my DO and ORP probes?
Paul G
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