Let's talk phosphate levels

[happyhourhero]

My tank is usually at around .26 and everything is pretty happy. Mostly acros. I’ve chased it in the past but these days, I don’t care much and tank is doing pretty well imo.

 

[SomeHappyFish]

I might have to dose phosphate... No matter how much I feed, they're always 0. Tank is now 14 months old.
Any tips is welcome.

 

[BeanAnimal]

My mixed reef hit well over 1ppm at some point 15 years ago. I think 1.2 or so at some point. The coral were fine — until they weren’t.

To this day, I am not sure what the tipping point was. I did very little testing and sporadically dosed two part, paid no attention to magnesium or nitrate. I changed MH bulbs a few times over a 9 month period and fiddled with actinics and turf scrubbers. SPS was hit or miss so I started using LaCl and that may be when things got worse before they got better.

In any case, I just walked away and let the tank run for 5 or so years and never touched it until a year or so ago. I came back to 0.2 phosphate, with no means of export.

I have no answers, but have not done a water change in years going on maybe 7 years and phosphate is maybe 0.06 to 0.08

 

[Science/G]

Here's an article I have referred back to many times.

https://www.reef2reef.com/ams/tank-parameters-of-some-masters.263/

 

[IzagenReef]

There are not many seemingly simple reef chemistry issues that are more vexing than phosphate.

Years ago we assumed that matching the ocean was desirable, but those levels seemed too low in practice (likely due to lack of particulate sources of P for corals in reef tanks). Then we read papers that showed reduced calcification of corals by elevated phosphate (it also does inhibit abiotic precipitation), and we picked low target levels. But is that really true in reef tanks? It seems maybe not, or at least not enough to be problematic.

So this poll is intended to help answer a very focused question about what phosphate levels are desirable. I'm not asking what levels you run, or what levels you read are best, but specifically if you have ever had high phosphate, and then lowered it, while doing not much else, and observed a positive and lasting effect on corals.

For purposes of this question, let's ignore any and all effects relating to pest algae, cyano, fish, etc.

Just coral effects for both hard and soft corals of all types. Effects can be color, growth rates, expansion/inflation, or a general perception of health. Please give some explanation in the follow up posts if you saw some type of positive effect.

 

[Faurek]

I bet discussion about phosphates is way too complex, reason being is phosphate and phosphorus content can differ and probably is different going from say 0.05 to .1 in days compared to months other thing might be the way phosphate gets down, probably different results from having lower phosphate from coral and algae growth like macros and stripping with gfo, I would argue that sea water has low phosphate but higher phosphorus content. Reason being is I live near a macroalgae reef and they don't seem tanked by low phosphate when the sun shines and they grow really fast. We need more research.

 

[ReeferZ1227]

I might have to dose phosphate... No matter how much I feed, they're always 0. Tank is now 14 months old.
Any tips is welcome.

Thats how it is until you get the rock/sand saturated. I was dosing about .15ppm/day for a few weeks in my waterbox. The good news is i was able to grow SPS from essentially week 2 of a tank started with dead rock. Anything but 0s.

 

[Randy Holmes-Farley Verified Community Expert]

I might have to dose phosphate... No matter how much I feed, they're always 0. Tank is now 14 months old.
Any tips is welcome.

Dosing is cheap and easy. Use food grade sodium phosphate and this calculator, using the entry for phosphate from potassium phosphate. I'd start at 0.05 ppm per day and scale up or down from there.

http://www.theplantedtank.co.uk/calculator.htm

 

[Troylee]

How about I always ran my tank .01 and it was good, but now I run it at .16 and it looks better than ever! Sticks are growing faster if you ask me! Dirty water and higher alk is what I’m liking personally.

 

[Randy Holmes-Farley Verified Community Expert]

I bet discussion about phosphates is way too complex, reason being is phosphate and phosphorus content can differ and probably is different going from say 0.05 to .1 in days compared to months other thing might be the way phosphate gets down, probably different results from having lower phosphate from coral and algae growth like macros and stripping with gfo, I would argue that sea water has low phosphate but higher phosphorus content. Reason being is I live near a macroalgae reef and they don't seem tanked by low phosphate when the sun shines and they grow really fast. We need more research.

Not sure what you mean by phosphorus. All types of P in seawater and reef tanks are phosphate. There are no chemicals present that a chemist would call phosphorus.

It includes inorganic orthophosphate, PO4, a few related inorganic compounds that involve more than one P, and a large number of organic phosphates that are both dissolved and particulate, all the way up to whole microorganisms such as viruses and bacteria. Organic phosphate include DNA, RNA, many proteins, phospholipids, etc.

 

[Randy Holmes-Farley Verified Community Expert]

Here's an article I have referred back to many times.

https://www.reef2reef.com/ams/tank-parameters-of-some-masters.263/

Just a few cautions on taking guidelines from existing tanks, no matter how good they are:

1. If the acceptable range of phosphate was 0.02 to 1 ppm, and all of those referenced tanks are in the 0.05 to 0.2 ppm range (as they seem to be), there is no inconsistency, but also no real info in the write up on the limits of phosphate acceptability.

2. Mimicing someone else's tank has big pitfalls unless you mimic everything they do, and have the same organisms. For example, they may have more organic phosphate present, such as from dissolved organics, bacteria from organic carbon dosing, or phyto from adding it.

The above 2 cautions apply to all sorts of parameters and procedures.

 

[Dom]

There are not many seemingly simple reef chemistry issues that are more vexing than phosphate.

Years ago we assumed that matching the ocean was desirable, but those levels seemed too low in practice (likely due to lack of particulate sources of P for corals in reef tanks). Then we read papers that showed reduced calcification of corals by elevated phosphate (it also does inhibit abiotic precipitation), and we picked low target levels. But is that really true in reef tanks? It seems maybe not, or at least not enough to be problematic.

So this poll is intended to help answer a very focused question about what phosphate levels are desirable. I'm not asking what levels you run, or what levels you read are best, but specifically if you have ever had high phosphate, and then lowered it, while doing not much else, and observed a positive and lasting effect on corals.

For purposes of this question, let's ignore any and all effects relating to pest algae, cyano, fish, etc.

Just coral effects for both hard and soft corals of all types. Effects can be color, growth rates, expansion/inflation, or a general perception of health. Please give some explanation in the follow up posts if you saw some type of positive effect.

Recently, I tested my PO4 for the first time in over a year and found it to be .85 using the Hanna ultra low test. And while there didn't appear to be any issues with the corals in the tank (Hammers and Zoas), I was trying to identify the cause of my Anemones shrinking in size.

I've added 1 cup of GFO to a reactor and it has dropped to .31 after 3 days. I am due to test today.

All of those months with elevated phosphates didn't appear to impact the corals, visually. They appear robust during these months of elevated PO4. Color is rich, expansion/inflation is as ambitious as it always was. Growth does appear to have slowed considerably.

 

[Randy Holmes-Farley Verified Community Expert]

Recently, I tested my PO4 for the first time in over a year and found it to be .85 using the Hanna ultra low test. And while there didn't appear to be any issues with the corals in the tank (Hammers and Zoas), I was trying to identify the cause of my Anemones shrinking in size.

I've added 1 cup of GFO to a reactor and it has dropped to .31 after 3 days. I am due to test today.

All of those months with elevated phosphates didn't appear to impact the corals, visually. They appear robust during these months of elevated PO4. Color is rich, expansion/inflation is as ambitious as it always was. Growth does appear to have slowed considerably.

Thanks. Please let us know if the drop appears to benefit the anemones. :)

 

[SpSDrew]

My phosphates went from 0.4 to 0.2 and I saw a decrease in coral coloration. I am slowly bringing them back up. My tank does best with 40 nitrate and 0.4 phosphate. I run a lot of light at a high par so I feel like that balance with the lighting Is key.

 

[Dom]

Thanks. Please let us know if the drop appears to benefit the anemones. :)

That will take some time as the benefit of corrections in chemistry are not immediately apparent.

 

[Randy Holmes-Farley Verified Community Expert]

That will take some time as the benefit of corrections in chemistry are not immediately apparent.

I understand. :)

 

[JayM]

Correct me if I'm wrong, but it seems that the consensus so far is that PO4 levels aren't terribly important, but finding what your reef likes and keeping it there may be.

 

[Faurek]

Not sure what you mean by phosphorus. All types of P in seawater and reef tanks are phosphate. There are no chemicals present that a chemist would call phosphorus.

It includes inorganic orthophosphate, PO4, a few related inorganic compounds that involve more than one P, and a large number of organic phosphates that are both dissolved and particulate, all the way up to whole microorganisms such as viruses and bacteria. Organic phosphate include DNA, RNA, many proteins, phospholipids, etc.

What I mean is that the phosphate kits to my understanding test PO4, as in phosphor binded to oxigen, but there might be other mixes with P, that organisms might be able to intake, while this would need probably millions invested.

 

[Faurek]

Correct me if I'm wrong, but it seems that the consensus so far is that PO4 levels aren't terribly important, but finding what your reef likes and keeping it there may be.

That is somewhat my understanding of it as well, it's what it likes from where it was cultured mixed with tank conditions and how aggressive was the change. I would love to understand it as well.

 

[rishma]

I do not have very good data to share because of how I responded when I discovered my high phosphates.

I had a very mature tank and stopped testing almost everything for over a year. Corals were healthy, growing, and I was not doing much. I got interested again and tested phosphate and it was over 0.5. I don’t remember exactly but it was near top of range for the Hanna phosphorous ULR.

I decided I needed to fix the “problem”. These were the days that 0.01-0.03 was the goal. Trying to get it and keep it that low caused a ton of issues and the corals were never as good again. For unrelated reasons, I ended up taking the tank down and moving before I learned better.