I have a 2 yr old 60gal Reef System which is mostly LPS with a few SPS corals. I currently dose BRS Soda Ash and AquaForest Calcium. My Alk is at 8.5 and Calcium is 360. My Nitrate is barely detectable at .01 and Phosphate is .23 A few corals haven’t looked as good as they should now for about 2 months. I am dosing 25ml a day of soda ash and 28.5 ml a day of calcium. I would like to see my Calcium higher and am wondering if dosing different brands is ok? Or would it just be better to use the BRS Calcium and just up each dose to equal amounts?
Dosing different brands
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Just temporarily increase your dose of Ca IMHO. until your Ca gets to where you want it then dose equally. - OR - you can use one of the many calculators to see how much CaCL2 - you need to add to bring your Ca to where you want it - divide that dose in 3 - and dose 1/3 each day for 3 days. keeping your dosing the same...
Dkmoo
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what do you feed? and what's your nutrient export? a tank shot would also help narrowing the possibilities. That No3 and Po4 levels are indicative that what you are feeding has a very different N to P ratio than what your tank absorbs and what your nutrient system exports.
All organisms also absorb N to P in fixed ratio so if one is undetectable it also prevents the other from absorbing. Coral likely getting starved now.
a 2 year old system should have enough biodiversity that includes high P eaters so generally the common stuff that we feed the reef should be pretty similar to what the tank uptakes. I'd look into this as the underlying cause of coral struggles.
the low CA is easy to fix as Mnfish suggested. The imbalance between input and output IMO is bigger underlying issue.
All organisms also absorb N to P in fixed ratio so if one is undetectable it also prevents the other from absorbing. Coral likely getting starved now.
a 2 year old system should have enough biodiversity that includes high P eaters so generally the common stuff that we feed the reef should be pretty similar to what the tank uptakes. I'd look into this as the underlying cause of coral struggles.
the low CA is easy to fix as Mnfish suggested. The imbalance between input and output IMO is bigger underlying issue.
Dkmoo
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I'm generalizing to demonstrate a principle for brevity - so probably should be more specific with more detail - Basically its a lot from a variety of articles i read over the years + stuff that people posted here and other forums. Some details:
1) All are based on the principles of the Redfield ratio, can google the basic principle, or check it out here, for example.
Redfield Ratio - an overview | ScienceDirect Topics
2) i don't mean that all organisms have the same fixed ratio - or that it really is a "fixed" one per se so i should rephrase - There are "sweet spots" where different organisms prefer or thrive in. here's one study done on an algae where they were exposed to different spectrums of the N/P ratio. Y is growth, X is time. diff dots = diff rations Square is the 16:1 Redfield ratio.
3) There's a few other ratios floating around, even in these forums, of different organisms, like one here:
Tank Trials: Ultra Low Maintenance Tanks | BRStv Investigates
I about died when Ryan read your name @FartyParty!! LOL! Also @WWC you guys sure know how to rock the coral deliveries! @revhtree Heh, all those years as a technical writer really paid off--i guess i gave them a quote they couldn't refuse. ;)
www.reef2reef.com
I do not have source for these numbers and i think at various times others have questions it too where the original thread (from 2017 i think, not the one i posted, i couldn't find the original one but do remember seeing it before) the original poster did put some source. For me however, what those numbers are exactly are less relevant than the general direction i'm seeing - ie, corals/algae are higher N to P, and the "meatier" things are low N high P
1) When there is an imbalance of NO3/PO4 - ie, high PO4 but no NO3 - In a closed system, this mathematically has to mean that what you put in is not matching what's absorbed/exported. Regardless if you believe different organisms have different "fixed" or even "sweet spot" N to P ratios for their absorption, the fact that you have a lot of P left but no N left suggests your tanks current inhabitants at least prefers a certain ratio of N to P that is not matching what you are feeding it - either you are feeding too much P, or not enough N.
2) Without understanding this, a typical relation for "high PO4" might be "go get a GFO" but is that really the correct method? do you really just are feeding too much P? or are you not feeding enough N? In either case, the underlying imbalance is not addressed, but is just masked. The latter will continue to starve your corals, while the former will lead to an arms race of increased external P control while not giving your tank a chance to establish natural high P absorbing biomes (whatever they may be, even if you don't subscribe the notion that a diverse biome would contain some organisms that are high P eaters which will flourish and act as natural check in a high P environment).
Whether or not that has true scientific backing i admit i do not know. I'm not a marine biologist nor have it read all the papers out there. at least this general understanding served as a guiding principle that have fit neatly in many of the common problems I faced and offered the right cause/effects that resulted in correct solutions. IE:
1) why fuge macro doesn't grow when there's no N but a lot of P, and after dosing N, P levels reduced and macro grew a lot
2) why new systems have more common P problems and why "keeping up with husbandry" and "maturing tank" over long term reduced P with similar feeding habits.
3) why systems that relied on external controls run into more problems later on and have to keep adding more systems, or run into problems when they take the external controls off
4) why certain foods, such as roid, or frozen cube shrimps, tend to raise P. esp in in a low P absorbing tank.
I understand there's a LOT more nuance and factors than what i mentioned above, but if there's anything that you believe differently from my general understanding above I'd love to hear you out. Always open to learning more/revise my current reefing theory.
Thx
Dkmoo
Valuable Member
@Bulk Reef Supply actually JUST did a couple of videos this week on what I mentioned above - but said more eloquently and more "neutral" in terms of their position, which is fine. One minor thing I don't agree with them (or at least hope they would have at least pointed out) is that they were only focusing on the ratio of NO3 to Po4, which they themselves agreed is only half the picture and measures only what's left in the water, and NOT the ratio of the total nutrition available to the system - therefore the ratio of the leftover no3/po4 may not be totally indicative of the state of the ratio in terms of nutrient absorption and the state of the balance or imbalance. However, the general principles of what they talked about in those video is what i wholeheartedly agree with, namely 1) different ratios enable different organisms to flourish more than others, 2) issues with able to control one but struggle with the other is an imbalance issue of what you put in vs what your biome absorb. Check them out if you don't feel like reading my wall of text 
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There is a lot of discussion about the Redfield ratio - Though its popular to discuss - and interesting - It has been debated since the 1930's how constant the ratio is, etc. The original studies were not based on the water concentrations of C, N and P - but rather the concentrations in biomass (phytoplankton) in varying parts of the world. After reading and reading - multiple articles over time - 1. Its really hard to make conclusions based on this ratio for our tanks, 2. Many organisms have different 'Redfield ratios' - cyanobacteria have NI'm generalizing to demonstrate a principle for brevity - so probably should be more specific with more detail - Basically its a lot from a variety of articles i read over the years + stuff that people posted here and other forums. Some details:
1) All are based on the principles of the Redfield ratio, can google the basic principle, or check it out here, for example.
Redfield Ratio - an overview | ScienceDirect Topics
www.sciencedirect.com
2) i don't mean that all organisms have the same fixed ratio - or that it really is a "fixed" one per se so i should rephrase - There are "sweet spots" where different organisms prefer or thrive in. here's one study done on an algae where they were exposed to different spectrums of the N/P ratio. Y is growth, X is time. diff dots = diff rations Square is the 16:1 Redfield ratio.
3) There's a few other ratios floating around, even in these forums, of different organisms, like one here:
Tank Trials: Ultra Low Maintenance Tanks | BRStv Investigates
I about died when Ryan read your name @FartyParty!! LOL! Also @WWC you guys sure know how to rock the coral deliveries! @revhtree Heh, all those years as a technical writer really paid off--i guess i gave them a quote they couldn't refuse. ;)
I do not have source for these numbers and i think at various times others have questions it too where the original thread (from 2017 i think, not the one i posted, i couldn't find the original one but do remember seeing it before) the original poster did put some source. For me however, what those numbers are exactly are less relevant than the general direction i'm seeing - ie, corals/algae are higher N to P, and the "meatier" things are low N high P
1) When there is an imbalance of NO3/PO4 - ie, high PO4 but no NO3 - In a closed system, this mathematically has to mean that what you put in is not matching what's absorbed/exported. Regardless if you believe different organisms have different "fixed" or even "sweet spot" N to P ratios for their absorption, the fact that you have a lot of P left but no N left suggests your tanks current inhabitants at least prefers a certain ratio of N to P that is not matching what you are feeding it - either you are feeding too much P, or not enough N.
2) Without understanding this, a typical relation for "high PO4" might be "go get a GFO" but is that really the correct method? do you really just are feeding too much P? or are you not feeding enough N? In either case, the underlying imbalance is not addressed, but is just masked. The latter will continue to starve your corals, while the former will lead to an arms race of increased external P control while not giving your tank a chance to establish natural high P absorbing biomes (whatever they may be, even if you don't subscribe the notion that a diverse biome would contain some organisms that are high P eaters which will flourish and act as natural check in a high P environment).
Whether or not that has true scientific backing i admit i do not know. I'm not a marine biologist nor have it read all the papers out there. at least this general understanding served as a guiding principle that have fit neatly in many of the common problems I faced and offered the right cause/effects that resulted in correct solutions. IE:
1) why fuge macro doesn't grow when there's no N but a lot of P, and after dosing N, P levels reduced and macro grew a lot
2) why new systems have more common P problems and why "keeping up with husbandry" and "maturing tank" over long term reduced P with similar feeding habits.
3) why systems that relied on external controls run into more problems later on and have to keep adding more systems, or run into problems when they take the external controls off
4) why certain foods, such as roid, or frozen cube shrimps, tend to raise P. esp in in a low P absorbing tank.
I understand there's a LOT more nuance and factors than what i mentioned above, but if there's anything that you believe differently from my general understanding above I'd love to hear you out. Always open to learning more/revise my current reefing theory.
Thx
ratios of 6;1 - 60:1. What is interesting is that Redfield had 2 original postulates - 1) that the N in seawater influenced the N in the biomass. and 2) that N in the biomass influenced the N in seawater - i.e. which came first the chicken or the egg. Redfield felt it was #2 that was the mechanism. In any case - with regards to our tanks if I have a nitrate of 160 and a Po4 of 10 - thats a 16:1 ratio. if I have a nitrate of 1.6 and a PO4 of .1 thats also a ratio of 16:1. So - though the ratio might be something to 'shoot for' - its not something I mess with in my tank. JMHO
EDIT: Apparently the emoji above is made when you try to type N : P without the spaces... So I mean N : P not 'N
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Randy Holmes-Farley
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I'm generalizing to demonstrate a principle for brevity - so probably should be more specific with more detail - Basically its a lot from a variety of articles i read over the years + stuff that people posted here and other forums. Some details:
1) All are based on the principles of the Redfield ratio, can google the basic principle, or check it out here, for example.
Redfield Ratio - an overview | ScienceDirect Topics
2) i don't mean that all organisms have the same fixed ratio - or that it really is a "fixed" one per se so i should rephrase - There are "sweet spots" where different organisms prefer or thrive in. here's one study done on an algae where they were exposed to different spectrums of the N/P ratio. Y is growth, X is time. diff dots = diff rations Square is the 16:1 Redfield ratio.
3) There's a few other ratios floating around, even in these forums, of different organisms, like one here:
Tank Trials: Ultra Low Maintenance Tanks | BRStv Investigates
I about died when Ryan read your name @FartyParty!! LOL! Also @WWC you guys sure know how to rock the coral deliveries! @revhtree Heh, all those years as a technical writer really paid off--i guess i gave them a quote they couldn't refuse. ;)
I do not have source for these numbers and i think at various times others have questions it too where the original thread (from 2017 i think, not the one i posted, i couldn't find the original one but do remember seeing it before) the original poster did put some source. For me however, what those numbers are exactly are less relevant than the general direction i'm seeing - ie, corals/algae are higher N to P, and the "meatier" things are low N high P
1) When there is an imbalance of NO3/PO4 - ie, high PO4 but no NO3 - In a closed system, this mathematically has to mean that what you put in is not matching what's absorbed/exported. Regardless if you believe different organisms have different "fixed" or even "sweet spot" N to P ratios for their absorption, the fact that you have a lot of P left but no N left suggests your tanks current inhabitants at least prefers a certain ratio of N to P that is not matching what you are feeding it - either you are feeding too much P, or not enough N.
2) Without understanding this, a typical relation for "high PO4" might be "go get a GFO" but is that really the correct method? do you really just are feeding too much P? or are you not feeding enough N? In either case, the underlying imbalance is not addressed, but is just masked. The latter will continue to starve your corals, while the former will lead to an arms race of increased external P control while not giving your tank a chance to establish natural high P absorbing biomes (whatever they may be, even if you don't subscribe the notion that a diverse biome would contain some organisms that are high P eaters which will flourish and act as natural check in a high P environment).
Whether or not that has true scientific backing i admit i do not know. I'm not a marine biologist nor have it read all the papers out there. at least this general understanding served as a guiding principle that have fit neatly in many of the common problems I faced and offered the right cause/effects that resulted in correct solutions. IE:
1) why fuge macro doesn't grow when there's no N but a lot of P, and after dosing N, P levels reduced and macro grew a lot
2) why new systems have more common P problems and why "keeping up with husbandry" and "maturing tank" over long term reduced P with similar feeding habits.
3) why systems that relied on external controls run into more problems later on and have to keep adding more systems, or run into problems when they take the external controls off
4) why certain foods, such as roid, or frozen cube shrimps, tend to raise P. esp in in a low P absorbing tank.
I understand there's a LOT more nuance and factors than what i mentioned above, but if there's anything that you believe differently from my general understanding above I'd love to hear you out. Always open to learning more/revise my current reefing theory.
Thx
I personally do not believe these sorts of experiments have ever shown that a ratio of N and P is important, as opposed to having a sufficient amount of both and not so much of either as to be toxic.
The graph you showed above for a freshwater algae not doing as well at 22 ppm phosphate as at lower levels is easily discounted (IMO) due to the potential for toxicity and/or trace element precipitation (such as iron phosphate) at that incredibly high phosphate level.
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