PO4 Help

smd189

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Good morning. After almost two years of undetectable PO4 on Salifert, I purchased a Hanna ULR and have been testing very high at over .2. Salifert still shows 0. I am running my fug at 19 hours a day and skimming heavy. I feed light once a day. I started adding GFO in the sump. Over the last week, the PO4 dropped down to .13 so yesterday I replaced the GFO and today, I’m back up to .19. What is going on? Everything else is in check. NO3 is 7-8. Thanks.
Shawn
 
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Just FYI but phosphate standards are avaialable online if you want to verify your test kits. Phosphorus cycle in reef systems is very complex. Keep in mind we can't test for particulate or dissolved organic phosphorus. And besides corals and algae messing with it sponges are messing with it and biofilms can sequester quite a bit. FWIW .2 mg/l is what corals are exposed to on many reefs in nature and some systems can run much higher. I'd also point out work done with corals in an aquarium at SOuthampton University* in Engalnd identified a threshold level of .03 mg/l to minimize the risk of phosphate deficiency in corals

Fig. 4 from this paper
DIP DOP POP.jpg

Here's a link to an article and video by Rich Ross on phosphate


Richard Ross What's up with phosphate

Links to Southampton's research:

An Experimental Mesocosm for Longterm Studies of Reef Corals

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

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

Phosphate deficiency promotes coral bleaching and is reflected by the ultrastructure of symbiotic dinoflagellates
 
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smd189

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If everything looks fine then why try to change a bunch of things? Maybe the hanna is off.
Thanks. My last post questioned which test should I believe. The consensus was that Hanna should be far better and more accurate than Salifert so I leaned into the Hanna. I also have considerable GHA so it makes sense that PO4 isn’t zero.
My main question is why would PO4 increase 12 hours after adding fresh GFO? Thanks.
 
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smd189

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Just FYI but phosphate standards are avaialable online if you want to verify your test kits. Phosphorus cycle in reef systems is very complex. Keep in mind we can't test for particulate or dissolved organic phosphorus. And besides corals and algae messing with it sponges are messing with it and biofilms can sequester quite a bit. FWIW .2 mg/l is what corals are exposed to on many reefs in nature and some systems can run much higher. I'd also point out work done with corals in an aquarium at SOuthampton University* in Engalnd identified a threshold level of .03 mg/l to minimize the risk of phosphate deficiency in corals

Fig. 4 from this paper
DIP DOP POP.jpg

Here's a link to an article and video by Rich Ross on phosphate


Richard Ross What's up with phosphate

Links to Southampton's research:

An Experimental Mesocosm for Longterm Studies of Reef Corals

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

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

Phosphate deficiency promotes coral bleaching and is reflected by the ultrastructure of symbiotic dinoflagellates
Thank you very much. I will watch/read each of these.
 
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Thanks. My last post questioned which test should I believe. The consensus was that Hanna should be far better and more accurate than Salifert so I leaned into the Hanna. I also have considerable GHA so it makes sense that PO4 isn’t zero.
My main question is why would PO4 increase 12 hours after adding fresh GFO? Thanks.
I would trust the Hanna ULR.

You saw the drop in value because of the GFO. My guess is that your rocks and sand are full of it, and once the concentration in the water dropped, the phosphate leached into the water in equilibrium with the rocks/sand. I bet you'll see it drop back down with fresh GFO. I would keep using small amounts and testing often.
 
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smd189

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I would trust the Hanna ULR.

You saw the drop in value because of the GFO. My guess is that your rocks and sand are full of it, and once the concentration in the water dropped, the phosphate leached into the water in equilibrium with the rocks/sand. I bet you'll see it drop back down with fresh GFO. I would keep using small amounts and testing often.
Thank you. Would this be PO4 inherently in the sand/rocks or due to detritus etc on the sand/rocks? With continued frequent GFO replacement what time frame would I expect to get a handle on it? Thank you.
 
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Pkunk35

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From what I understand , sand and rock will absorb phosphate to equalize out with the water column. So it is like the water column but “slower” so if you remove some phos from the water it takes a while for that rock phos to leach out back to equilibrium but phosphate will be overall lower from that GFo.

GFO is instantly fast so you have to test constantly while using it IMO or else you risk 0 phos and this is a killer.

IMO clear out gha bc that is basically a phosphate vacuum giving you a misleading reading and not your systems true phosphate needs. Get the requirements of the coral and bac minus the algaes, for me it’s easier to think about this way
 

nereefpat

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Thank you. Would this be PO4 inherently in the sand/rocks or due to detritus etc on the sand/rocks?
The white dry rock that people start their tanks with is sometimes full of it. You have a 2 year old tank, though...so I don't know for sure.

With continued frequent GFO replacement what time frame would I expect to get a handle on it? Thank you.
Hard to say. Some people constantly run a small amount of GFO. It looks like you're close, if you're shooting for 0.1 or less. I would use small amounts and test every couple days.
 

BanjoBandito

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Just FYI but phosphate standards are avaialable online if you want to verify your test kits. Phosphorus cycle in reef systems is very complex. Keep in mind we can't test for particulate or dissolved organic phosphorus. And besides corals and algae messing with it sponges are messing with it and biofilms can sequester quite a bit. FWIW .2 mg/l is what corals are exposed to on many reefs in nature and some systems can run much higher. I'd also point out work done with corals in an aquarium at SOuthampton University* in Engalnd identified a threshold level of .03 mg/l to minimize the risk of phosphate deficiency in corals

Fig. 4 from this paper
DIP DOP POP.jpg

Here's a link to an article and video by Rich Ross on phosphate


Richard Ross What's up with phosphate

Links to Southampton's research:

An Experimental Mesocosm for Longterm Studies of Reef Corals

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

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

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

In 10 years we'll be dosing phosphate. lol. The phosphate debate is so insane. We used to never test for it. Now we are militant about suppressing it. Ask most reefers why they want low phosphates and they'll say "BECAUSE ALGAE".
 
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smd189

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From what I understand , sand and rock will absorb phosphate to equalize out with the water column. So it is like the water column but “slower” so if you remove some phos from the water it takes a while for that rock phos to leach out back to equilibrium but phosphate will be overall lower from that GFo.

GFO is instantly fast so you have to test constantly while using it IMO or else you risk 0 phos and this is a killer.

IMO clear out gha bc that is basically a phosphate vacuum giving you a misleading reading and not your systems true phosphate needs. Get the requirements of the coral and bac minus the algaes, for me it’s easier to think about this way
Thank you. I have been testing twice a day for two weeks and changing GFO every other day. Over this time the PO4 has fluctuated between .13 and .23. It has gone up and down but no trend. Nothing else has changed. I always thought GFO would strip PO4 quickly, but it doesn’t seem to be doing much of anything.
 

Pkunk35

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You might have a ton absorbed by the rock and sand. I had a nano 20g that i constantly ran chemipure in which kept in “balance”. Initially tho this tank ran 5 yrs with no phosphate reduction and had huge algae problems. I think eventually if I just always kept the chemipure running 24/7, eventually I’d strip it all out.

As said previously some people run tiny bits of gfo and this helps them I guess keep the phos at a certain level in the column. So I’d think rate of reduction of phosphate is going to be about surface area of that gfo and water contact. It’s going to be variable depending how you use it.
 
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doubleshot00

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Thanks. My last post questioned which test should I believe. The consensus was that Hanna should be far better and more accurate than Salifert so I leaned into the Hanna. I also have considerable GHA so it makes sense that PO4 isn’t zero.
My main question is why would PO4 increase 12 hours after adding fresh GFO? Thanks.
I took your post as nothing was wrong with your tank. If you have GHA stick with the GFO or get some rowaphos. Also buy another Salifert test.
 
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