You're fine. Here's what I think and links to the research. (Sorry in advance for the data bomb.) To add to your data overload, nitrates and phosphates are only dissolved inorganic forms. There's also particualte and dissolved organic forms we can't test for. So while there's solid research to keep PO4 above .03 as ppointed out above it's possible depending on the food webs in a system coral might be able to get enough phosphorus from particulate and dissolved organic forms, And to add to the complexity, if there's enough particulate and dissolved organic phosphorus it's possible coral's might be the source of increasing PO4 levels.
This system was at .4 mg/l PO4 when this video was taken. Nitrates were negligable.
I don't see any reason to keep PO4 lower than the .03 mg/l threshold level identified by Southampton University in England. Since they determined it by looking at phosphorus deficiency in corals maintained in aquaria for up to around a decade seems like a definitive lower number until we can quantify particulate and dissloved organic P used by corals. Upwelling can expose to corals to .3 mg/l so that seems like a fine number also. And at the higher end the sexually reproduced corals at the Steinhart Aquarium are being grown out with .9 mg/l PO4 and 50 mg/l Nitrate (Rich Ross is part of the research team in case anyone was wondering).
Here's more links:
https://www.cambridge.org/core/jour...-reef-corals/AFB1CF4CB68823BD13AD254623FD3C7CAn Experimental Mesocosm for Longterm Studies of Reef Corals
Phosphate Deficiency:
Nutrient enrichment can increase the susceptibility of reef corals to bleaching:
https://www.nature.com/articles/nclimate1661
Ultrastructural Biomarkers in Symbiotic Algae Reflect the Availability of Dissolved Inorganic Nutrients and Particulate Food to the Reef Coral Holobiont:
https://www.frontiersin.org/articles/10.3389/fmars.2015.00103/full
Phosphate deficiency promotes coral bleaching and is reflected by the ultrastructure of symbiotic dinoflagellates
https://www.sciencedirect.com/science/article/pii/S0025326X17301601?via=ihub
Effects of phosphate on growth and skeletal density in the scleractinian coral Acropora muricata: A controlled experimental approach
https://www.sciencedirect.com/science/article/pii/S0022098111004588
High phosphate uptake requirements of the scleractinian coral Stylophora pistillata
http://jeb.biologists.org/content/214/16/2749.full
Phosphorus metabolism of reef organisms with algal symbionts
https://esajournals.onlinelibrary.w...98e60zfBEvx5IcIVGhmlpUYmzIJuqUNVm0sG8_0vth6lq
https://therichross.com/skeptical-reefkeeping-ix-test-kits-chasing-numbers-and-phosphate/
Sponge symbionts and the marine P cycle
https://www.pnas.org/content/112/14/4191
Phosphorus sequestration in the form of polyphosphate by microbial symbionts in marine sponges
https://www.pnas.org/content/112/14/4381
Fig 4 from "Phosphorus metabolism of reef organisms with algal symbionts"
This system was at .4 mg/l PO4 when this video was taken. Nitrates were negligable.
I don't see any reason to keep PO4 lower than the .03 mg/l threshold level identified by Southampton University in England. Since they determined it by looking at phosphorus deficiency in corals maintained in aquaria for up to around a decade seems like a definitive lower number until we can quantify particulate and dissloved organic P used by corals. Upwelling can expose to corals to .3 mg/l so that seems like a fine number also. And at the higher end the sexually reproduced corals at the Steinhart Aquarium are being grown out with .9 mg/l PO4 and 50 mg/l Nitrate (Rich Ross is part of the research team in case anyone was wondering).
Here's more links:
https://www.cambridge.org/core/jour...-reef-corals/AFB1CF4CB68823BD13AD254623FD3C7CAn Experimental Mesocosm for Longterm Studies of Reef Corals
Phosphate Deficiency:
Nutrient enrichment can increase the susceptibility of reef corals to bleaching:
https://www.nature.com/articles/nclimate1661
Ultrastructural Biomarkers in Symbiotic Algae Reflect the Availability of Dissolved Inorganic Nutrients and Particulate Food to the Reef Coral Holobiont:
https://www.frontiersin.org/articles/10.3389/fmars.2015.00103/full
Phosphate deficiency promotes coral bleaching and is reflected by the ultrastructure of symbiotic dinoflagellates
https://www.sciencedirect.com/science/article/pii/S0025326X17301601?via=ihub
Effects of phosphate on growth and skeletal density in the scleractinian coral Acropora muricata: A controlled experimental approach
https://www.sciencedirect.com/science/article/pii/S0022098111004588
High phosphate uptake requirements of the scleractinian coral Stylophora pistillata
http://jeb.biologists.org/content/214/16/2749.full
Phosphorus metabolism of reef organisms with algal symbionts
https://esajournals.onlinelibrary.w...98e60zfBEvx5IcIVGhmlpUYmzIJuqUNVm0sG8_0vth6lq
https://therichross.com/skeptical-reefkeeping-ix-test-kits-chasing-numbers-and-phosphate/
Sponge symbionts and the marine P cycle
https://www.pnas.org/content/112/14/4191
Phosphorus sequestration in the form of polyphosphate by microbial symbionts in marine sponges
https://www.pnas.org/content/112/14/4381
Fig 4 from "Phosphorus metabolism of reef organisms with algal symbionts"
