PO4 can't get it right

[jackinthebox8332]

Hello everyone, I've had my 100 gallon FOWLR tank for a few years. In peer posts I mentioned I am now going for my soft corals and want to add an anemone. I research everything and as you all know, water parameters need to be on the money for these animals. All of my water parameters are good except for phosphate. I can't get it down, always at 0.25, sometimes 0.22. I've read all the suggestions on line and implemented them.
Could you experienced reefers tell me what you are doing to get PO4 in acceptable range?
Thanks again, jackinthebox.

 

[griss]

Do you run GFO? If so, how are you using it? Media bag? Media reactor?

 

[Uncle99]

Hello everyone, I've had my 100 gallon FOWLR tank for a few years. In peer posts I mentioned I am now going for my soft corals and want to add an anemone. I research everything and as you all know, water parameters need to be on the money for these animals. All of my water parameters are good except for phosphate. I can't get it down, always at 0.25, sometimes 0.22. I've read all the suggestions on line and implemented them.
Could you experienced reefers tell me what you are doing to get PO4 in acceptable range?
Thanks again, jackinthebox.

Which test kit. Most can’t read much below 0.25ppm. The colour change is so faint, hard to tell.
If the kit is Hanna phosphate or phosphorus I find there readings good ball park.

I’ve run .25ppm for 5 years, so I think if you can keep it say .1-.25 consistently, I’d leave that. Phosphate is used by many. Over time, it builds up so watch for increases. If that happens you can run your choice GFO to mop that up a bit.

Its more about stability than any one number. (Within traditional bands)

 

[Timfish]

.25 is an acceptable level. Upwelling exposes reefs to levels as high as .3 mg/l. The notion PO4 has to be kept at near nonexistant levels ignored research showing it's importance for corals. Here's a recent video by Charles Delbeek:

And depending on the food webs in a reef system corals may be the source of PO4 as they will feed on particulate and dissolved organic phosphorus (which we can't test for) and dump excess PO4 into the water.


Fig 4 from "Phosphorus metabolism of reef organisms with algal symbionts"


Here's a data bomb if you want to read more about it.

Phosphate Deficiency:
Nutrient enrichment can increase the susceptibility of reef corals to bleaching:

Nutrient enrichment can increase the susceptibility of reef corals to bleaching - Nature Climate Change

Increased dissolved inorganic nitrogen (DIN) concentrations in sea water have been linked to a reduction of the temperature threshold at which corals bleach, however, the mechanism underlying this change is not known. This phenomenon is now explained in terms of increased phosphatase activities...

www.nature.com

Ultrastructural Biomarkers in Symbiotic Algae Reflect the Availability of Dissolved Inorganic Nutrients and Particulate Food to the Reef Coral Holobiont:

Frontiers | Ultrastructural Biomarkers in Symbiotic Algae Reflect the Availability of Dissolved Inorganic Nutrients and Particulate Food to the Reef Coral Holobiont

Reef building corals associated with symbiotic algae (zooxanthellae) can access environmental nutrients from different sources, most significantly via the up...

www.frontiersin.org

Phosphate deficiency promotes coral bleaching and is reflected by the ultrastructure of symbiotic dinoflagellates

Phosphate deficiency promotes coral bleaching and is reflected by the ultrastructure of symbiotic dinoflagellates

Enrichment of reef environments with dissolved inorganic nutrients is considered a major threat to the survival of corals living in symbiosis with din…

www.sciencedirect.com

Effects of phosphate on growth and skeletal density in the scleractinian coral Acropora muricata: A controlled experimental approach

Effects of phosphate on growth and skeletal density in the scleractinian coral Acropora muricata: A controlled experimental approach

Phosphate contamination can negatively affect corals, modifying growth rates, skeletal density, reproduction, mortality, and zooxanthellae. We determi…

www.sciencedirect.com

High phosphate uptake requirements of the scleractinian coral Stylophora pistillata

High phosphate uptake requirements of the scleractinian coral Stylophora pistillata

SUMMARYSeveral untested aspects of the regulation of inorganic nutrient uptake were examined using nutrient depletion experiments with the symbiotic coral Stylophora pistillata. The total inhibition of phosphate uptake in artificial seawater lacking sodium indicates the involvement of a...

jeb.biologists.org

Skeptical Reefkeeping 9: Test Kits, Chasing Numbers and Phosphate – Rich Ross

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