Let's talk phosphate levels

[schooncw]

I really don't think phosphates levels (obviously not zero) matter as much if you have a mature reef...the corals are soaking up the phosphates and there is little room for other bad stuff to grow since all the real estate is taken by corals But if you don't have a mature reef, then I think it is best to keep phosphates in the lower range as that is probably how most of your acquired corals are used to and discourages other bad things to grow on empty rocks.

My conception of low phosphates are shattered when I see gorgeous full SPS tanks that is running above 0.5ppm. Case in point, the recent TOTM winner is running phosphates at 0.5-0.66 (maxed out on his hanna tester). https://www.reef2reef.com/threads/reef-of-the-month-november-2024-aaronfreefs-sps-dream.1080686/

I posted yesterday. My 30 year old LPS dominant system is looking good. PO never falls below 1.0. As time goes on, I am tempted to try LAN again but this time go much, much slower.

 

[schooncw]

In my small reef of 15 gallons I deal with a lot of rapidly fluctuating values. Over the past 3 months phosphate has been rapidly increasing to a high of over .9. Noticed effects on all corals LPS being the most pronounced but even on the hardy zoas. Vast improvements were noted within a week of utilizing lanthanum chloride to swing things downward. Better coloration and extension were apparent.

How did you dose LAN?

 

[Curiousbranching]

Can you explain a bit more what you mean by the first half of that sentence?

In my tank, I’ve noticed that when nitrate and phosphate levels are relatively high (for me, that means around 15-20 ppm NO3 and 0.2 ppm phosphate or higher), including what I’m dosing via my dosing pump and the nutrients already present in the tank, I can push PAR intensity up to over 500 and maintain KH at 9 or higher without any issues.

On the flip side, if nutrient levels drop too low—especially phosphate going below 0.05 ppm—my corals start closing their polyps and may even develop burnt tips if I let it continue for a few days. Nitrate isn’t usually a problem in my tank since I have a lot of tangs in my 120-gallon system, and I also dose a solution of ammonia daily, around 0.2 ppm spread out over 24 hours.

So, I’m guessing the issue mainly comes down to a lack of phosphate for the corals to use during photosynthesis. Whenever this happens, I have to lower the PAR intensity and reduce KH (from KH 9+ to around KH 7-7.5); otherwise, I end up with widespread RTN or STN on the corals.

 

[Jimbo327]

I do have a theory. I believe corals are very similar to plants. Plants fertilizer is a mix of nitrogen-phosphorus-potassium, and plants use light to grow. And there are fertilizer mixes with different % of the 3 elements for different types of plants. Some plants prefer higher phosphorus content, while another plant will die in high phosphorus content. Some can survive is wide range of these conditions, while some need a certain condition.

So I feel like that is how I should look at my own tank like a little garden. So how much of each element may also be dependent on the light intensity as well, the more light has more energy, and vice versa. Some plants want more light, other don't. So a mixed reef is probably way harder to make happy since you need different types of conditions to make all the different corals happy. Plants can adapt to your condition, so that is why stability has been harped on as key to growth.

This is why there are so many different tanks with different nitrate/phosphate numbers, and they are all doing good. The corals that didn't do well probably already died, and the ones that survived are the ones thriving in the tank after they have adjusted. And some corals can just thrive in wide conditions aka easy or aquacultured corals.

Maybe we should look to apply what gardeners already learned. The ratio of N-P-P we should maintain, and what range can accommodate the most corals. Personally, I try to maintain an easy range is 10-20 ppm Nitrate, 0.1-0.2 ppb phosphates, and 400-420 potassium. But maybe 30-40 ppm Nitrate is just fine with 0.3-0.4 ppb phosphates...during the summer (aka higher light intensity). Gardeners use different ratios depending on type of plants and the season to promote growth in flowers or roots, etc. Obviously, in reef, we have to also maintain Ca/Alk/Mag as well.

Sorry for the long post, but just getting my thoughts out.

 

[bubbgee]

hard to explain.

All I can say is I did feel I was walking a dangerous line with them that low. I frequently tested zero and I would dose some neophos

Unrelated to my phosphate feelings - i made two changes at once - I tried a new coral food, and I added a plank auto feeder with their reef jerky product.

After a week I did my phosphate test and I was at .9 and I was shocked. This tank has been stable at .05 or less for over a year. July 2024 is when I had the spike to .9

I quickly lowered to .5 in a few days with Phosguard. Then worked on slowly lowering back to normal. But, the tank resisted and never really wanted to go back to original levels. I got it to start lowering and then it goes back up. Then I noticed - everything was fine, and my gonis were extending more - was it growth vs happiness - who knows.

I decided to see how things go and the tank stabilized at .45 and now stays in the .4 to .5 range and it been there since.

Do you think the rocks are leaching phosphates to keep things balanced? I've struggled with phosphates before with an older tank and three year old rocks and when I started a new tank with new live rocks, I haven't had the issue yet.

 

[Rolliad]

I do have a theory. I believe corals are very similar to plants. Plants fertilizer is a mix of nitrogen-phosphorus-potassium, and plants use light to grow. And there are fertilizer mixes with different % of the 3 elements for different types of plants. Some plants prefer higher phosphorus content, while another plant will die in high phosphorus content. Some can survive is wide range of these conditions, while some need a certain condition.

So I feel like that is how I should look at my own tank like a little garden. So how much of each element may also be dependent on the light intensity as well, the more light has more energy, and vice versa. Some plants want more light, other don't. So a mixed reef is probably way harder to make happy since you need different types of conditions to make all the different corals happy. Plants can adapt to your condition, so that is why stability has been harped on as key to growth.

This is why there are so many different tanks with different nitrate/phosphate numbers, and they are all doing good. The corals that didn't do well probably already died, and the ones that survived are the ones thriving in the tank after they have adjusted. And some corals can just thrive in wide conditions aka easy or aquacultured corals.

Maybe we should look to apply what gardeners already learned. The ratio of N-P-P we should maintain, and what range can accommodate the most corals. Personally, I try to maintain an easy range is 10-20 ppm Nitrate, 0.1-0.2 ppb phosphates, and 400-420 potassium. But maybe 30-40 ppm Nitrate is just fine with 0.3-0.4 ppb phosphates...during the summer (aka higher light intensity). Gardeners use different ratios depending on type of plants and the season to promote growth in flowers or roots, etc. Obviously, in reef, we have to also maintain Ca/Alk/Mag as well.

Sorry for the long post, but just getting my thoughts out.

Having freshwater setups that are planted I tend to agree with this. While coral are not plants, I do see parallels here in how they react to nitrate, phosphate, light and flow to plants within my FW setups.

 

[VintageReefer]

Do you think the rocks are leaching phosphates to keep things balanced? I've struggled with phosphates before with an older tank and three year old rocks and when I started a new tank with new live rocks, I haven't had the issue yet.

Yes and what I believe is I accidentally raised my balance. Or equilibrium.

Now I need to constantly remove phosphates, so the rocks are constantly leaching phosphates, until the numbers actually come down and stay down. I’ve done this before. It takes months

 

[Randy Holmes-Farley]

I do have a theory. I believe corals are very similar to plants. Plants fertilizer is a mix of nitrogen-phosphorus-potassium, and plants use light to grow. And there are fertilizer mixes with different % of the 3 elements for different types of plants. Some plants prefer higher phosphorus content, while another plant will die in high phosphorus content. Some can survive is wide range of these conditions, while some need a certain condition.

So I feel like that is how I should look at my own tank like a little garden. So how much of each element may also be dependent on the light intensity as well, the more light has more energy, and vice versa. Some plants want more light, other don't. So a mixed reef is probably way harder to make happy since you need different types of conditions to make all the different corals happy. Plants can adapt to your condition, so that is why stability has been harped on as key to growth.

This is why there are so many different tanks with different nitrate/phosphate numbers, and they are all doing good. The corals that didn't do well probably already died, and the ones that survived are the ones thriving in the tank after they have adjusted. And some corals can just thrive in wide conditions aka easy or aquacultured corals.

Maybe we should look to apply what gardeners already learned. The ratio of N-P-P we should maintain, and what range can accommodate the most corals. Personally, I try to maintain an easy range is 10-20 ppm Nitrate, 0.1-0.2 ppb phosphates, and 400-420 potassium. But maybe 30-40 ppm Nitrate is just fine with 0.3-0.4 ppb phosphates...during the summer (aka higher light intensity). Gardeners use different ratios depending on type of plants and the season to promote growth in flowers or roots, etc. Obviously, in reef, we have to also maintain Ca/Alk/Mag as well.

Sorry for the long post, but just getting my thoughts out.

Just on the potassium comment, seawater contains a lot of potassium and so it’s not in short supply, not needing constant supplementing in many cases. Foods may add plenty to balance uptake, although some folks do see potassium declines.

 

[ElementReefer]

I can give my expected rationale, but its an unproven theory.

Like many things in a reef tank, phosphate is taken up by organisms using active transporters. These are proteins in the cell membranes of cells that face the external fluid (or maybe inside of spaces that have free transport of ions with the water). They use energy to pull in phosphate ions one at a time. Even humans have them in their small intestine.

When phosphate is in short supply, organisms can increase the number of transporters to be able to optimize their uptake capacity.

When phosphate is plentiful, they reduce the number of these transporters.

They may also have more than one transporter type, and may change the types as needed.

These changes take time (hours to days), and that normally is not a problem in the ocean where changes are slow.

If a coral has adapted to local conditions as best it can by optimizing its transporters, and then there's a sudden increase or decrease in phosphate, they may not get enough or are force fed too much.

Think of it like a person at a drinking fountain with their mouth open a certain amount. If the water suddenly increases in flow they may gag on the forced water intake. if the flow reduces, the water intake slows greatly.

Too much or too little phosphate inside cells is not a good thing. It can be a big problem in people too.

I think this is right on. Biological systems have A) mechanisms to maintain homeostasis and B) buffer capacity if equilibrium is temporarily lost. Coral, especially SPS, have almost no buffer capacity. On top of that, they’re managing not only their own cellular metabolism but the zooxanthellae. It’s kind of a miracle they exist at all.

 

[schooncw]

Do you think the rocks are leaching phosphates to keep things balanced? I've struggled with phosphates before with an older tank and three year old rocks and when I started a new tank with new live rocks, I haven't had the issue yet.

I don’t know about keeping things balanced but the rock in my 120 LPS dominant tank is 32 or so years old. My PO never drops below 1.0 and being overstocked and overfed, prob never will.
Funny thing is, everything looks great, no nuisance algae either

 

[Rolliad]

Well, I'm 9 days in to trying to bring my phosphate level down. According to my math, I should have hit the detectable range on my Hannah checker (2.50 ppm) this morning. However, that wasn't the case. I'm still above the max of my test kits. That means that my phosphate was much higher than I thought it was. That's the problem with ICP, is that they are a delayed test.

I've been going really slow in bringing it down though...

Good news is, polyp extension continues to improve across the board daily as I dose the PhosBan-L.

 

[Randy Holmes-Farley]

Well, I'm 9 days in to trying to bring my phosphate level down. According to my math, I should have hit the detectable range on my Hannah checker (2.50 ppm) this morning. However, that wasn't the case. I'm still above the max of my test kits. That means that my phosphate was much higher than I thought it was. That's the problem with ICP, is that they are a delayed test.

I've been going really slow in bringing it down though...

Good news is, polyp extension continues to improve across the board daily as I dose the PhosBan-L.

What sort of calculation did you do?

 

[Rolliad]

What sort of calculation did you do?

I took what my level was in my ICP - the amount that the PhosBan-L should be removing per day. Should have brought it down to a readable level today based on what it was in the last ICP. I suspect it was higher as I was feeding ReefRoids not realizing that it was probably the main source of my phosphates for several days after my sample. So my number was probably far higher than my ICP result said - unfortunately, I'm blind on that number in real time until the level drops enough.

 

[Randy Holmes-Farley]

I took what my level was in my ICP - the amount that the PhosBan-L should be removing per day. Should have brought it down to a readable level today based on what it was in the last ICP. I suspect it was higher as I was feeding ReefRoids not realizing that it was probably the main source of my phosphates for several days after my sample. So my number was probably far higher than my ICP result said - unfortunately, I'm blind on that number in real time until the level drops enough.

Such a calculation will fail for a couple of reasons, most notably because it does not account for phosphate coming off calcium carbonate surfaces as the levels begin to decline.

 

[Rolliad]

Such a calculation will fail for a couple of reasons, most notably because it does not account for phosphate coming off calcium carbonate surfaces as the levels begin to decline.

Today I learned...

How do I account for such an unknown?

 

[bubbgee]

Today I learned...

How do I account for such an unknown?

The way I've been managing is via testing. I'm using the Trident NP to monitor. I won't vouch for accuracy but I maintain a range (.1 to .2 phosphates and 20-40 nitrates)

 

[geologeek]

Today I learned...

How do I account for such an unknown?

By just going slowly and surely as you are and keep on reefing.

You cant know such unknowns......just carry on as you are and keep an eye on your tests and you will get there.

 

[bubbgee]

I don’t know about keeping things balanced but the rock in my 120 LPS dominant tank is 32 or so years old. My PO never drops below 1.0 and being overstocked and overfed, prob never will.
Funny thing is, everything looks great, no nuisance algae either

Yeah I think that will work for LPS and softies. I have a mixed reef and want to maintain something reasonable. My export is doing quite well now (probably too well) that I have to feed reef roids and dose neophos and neonitro to keep within range.

 

[Randy Holmes-Farley]

Today I learned...

How do I account for such an unknown?

Use it as a limiting dose so you do not over do it, and repeat it as needed. One cannot calculate how much is bound in a reef tank.

 

[Rolliad]

By just going slowly and surely as you are and keep on reefing.

You cant know such unknowns......just carry on as you are and keep an eye on your tests and you will get there.

Maybe we can though? If rock leaches at a rate consistent to the amount reduced for instance, that could be accounted for. I just don't happen to know.