Lowering PO4 against rocks/sand buffering effect

[jrmailo]

I am experiencing a full blown acropora crash from elevated PO4.

This whole thing transpire on a time span of about a year. Through out the whole ordeal, the only parameters that changed has been my PO4. Everything else has been kept stable.

My tank had always been stable at around 0.15ppm PO4 with little to no nutrients management by me.

Despite getting great growth at this level, I decided to chase better coloration by reducing phosphate via LaCl dosing. However, I overdid it and as my PO4 fell too fast. As expected this lead to zero growth, paling and some basal recession on some of my acro colonies. All sign of starvations.

In an effort to revert everything back to "normal", I stopped LaCl and started dosing PO4 instead to raise my level back up.

Once PO4 creep back up, my acro did look better. However, before long, my acro started to look pale and unhealthy again. At this point my PO4 was around 0.2-0.25ppm.

Despite PO4 being elevated, my acro seemed starved, paling, slow tissue loss at the base. So naturally, I continued increasing PO4 to combat the symptoms.

It never occurred to me that my acros might be stressed because of high PO4.... At least not until I pushed my tank above +0.45ppm of PO4 that a third of all my acros died overnight....

For the last 3 months, I had been trying to reduce my phosphate via LaCl again. However, I am unable to reduce my PO4 gradually in a controlled manner. It has been a vicious cycle of my PO4 spiking up and down. And every time that there is a spike, more acros die.

Generally, I would have to dose a big quantity of LaCl to reduce my PO4 below 0.4ppm. Once below 0.4ppm, I would dose LaCl on a doser at 1 hour interval to keep my PO4 steady. But within a few days, my PO4 would SUDDENLY spike all the way above 0.4ppm...

I had tried increasing the amount of LaCl dosed on the hourly timer, only to see the PO4 drop gradually for a few days and then without fail spike above 0.4ppm overnight.

The only conclusion I can come to is that the the rocks and sand are actively absorbing and desorbing the PO4 in the system depending on how saturated the rocks/sand compared to the free PO4 in the water.

If the rocks/sand has lower level of PO4 than the water, they absorb PO4 out of the water. This is when even a small dose of LaCl will drop the PO4 in the the water significantly.

Once the rocks/sand are saturated with PO4, they desorb and unbind PO4. This is when my PO4 suddenly spike and would require a big dose of LaCl to over come the buffering capacity of the rocks and sand.

I am at my wits end on how to stop these spikes from happening. As of today I lost 80% of my acros....

Any advice is appreciate.

 

[Randy Holmes-Farley Verified Community Expert]

None of those absolute levels of phosphate prevent others from keeping them, at least not for many species of acropora. Perhaps the changes were stressful, or perhaps it was unrelated to phosphate.

 

[jrmailo]

None of those absolute levels of phosphate prevent others from keeping them, at least not for many species of acropora. Perhaps the changes were stressful, or perhaps it was unrelated to phosphate.

Hi Randy,

I agree that many has been able to keep their acros even above 1ppm. But I had also read that they themselves lost multiple acros that presumably were intolerant of higher po4 levels. I can attest to this as I have a couple of colonies that are still happily growing with great colors, but they are the super minority in my tank.

I believe that both low end and high end level of PO4 can lead to starvation. Low end is pretty self explanatory. In high end, I suspect that the coral is culling their own zooxanthellae in order to maintain homoeostasis. In other words, die back to limit the uptake and prevent overload of PO4.

 

[Pod_01]

I believe that both low end and high end level of PO4 can lead to starvation. Low end is pretty self explanatory. In high end, I suspect that the coral is culling their own zooxanthellae in order to maintain homoeostasis. In other words, die back to limit the uptake and prevent overload of PO4.

Interesting idea about the elevated PO4. I had the understanding that corals are not that good at obtaining PO4 and drastic reduction in PO4 stresses them.

From my own experience I had no issues when PO4 increased but I always had bad outcomes when my PO4 dropped…. Sometimes lasting effects.

I do hope things improve, nothing worse then watching acros STN one by one.

Good luck,

 

[jrmailo]

Interesting idea about the elevated PO4. I had the understanding that corals are not that good at obtaining PO4 and drastic reduction in PO4 stresses them.

From my own experience I had no issues when PO4 increased but I always had bad outcomes when my PO4 dropped…. Sometimes lasting effects.

I do hope things improve, nothing worse then watching acros STN one by one.

Good luck,

it’s just a hunch. But when I reduced PO4 some of the colonies browned up and regained a bit of their coloration back in just a few days. From my perspective, this seem like the corals were now up-regulating their zooxanthelle expression to match the new parameter. Ie they needed more zooxanthelle to capture PO4 from the water column.

Same concept would apply to a new frag brown out. Maybe it’s getting less light than in the store. Maybe less NO3 or PO4 than their previous environment. In all cases, it needs more zooxanthelle to meet the demand of the coral.

In my case, browning up was probably a good thing. At least they were moving away from ghostly pale and bleaching. However, it didn’t mean much when my PO4 spike up over night and my coral ended up losing another chunk of flesh..

 

[reefpanda]

Could it be due to bacterial issue rather than Po4?

 

[jrmailo]

Could it be due to bacterial issue rather than Po4?

I do not think so. While I have no way of testing for bacterial infection, I get a wave of massive loss each timePO4 rebound above 0.4ppm

 

[jrmailo]

80% of all my SPS in this picture are either dead or too gone to save. I can’t even arrest the STN at this point in time

 

[Curiousbranching]

IME, there’s no quick fix for the kind of situation you’re dealing with. I’ve personally been in the exact same boat and ended up losing almost all the acros in my tank.

The only way I found to recover was to keep things as stable as possible and let the corals slowly bounce back on their own. Any kind of adjustment during this time just made things worse.

If you’ve already found the sweet spot where PO4 is balanced with LaCl, then stick with it—and keep a close eye on things so phosphate doesn’t drop too much in a single day. IMO, when we change PO4 levels too quickly, it causes a shift in the microbial population, and that stresses the acros out big time.

Hang in there—stability is your best friend right now.

 

[rishma]

I am really sorry to read this.

I too have battled the phosphate yo-yo as you describe. I have never used LC, so I cannot comment on that method.

More recently I have been able to avoid this yo-yo when reducing phosphates by changing how I used GFO. Basically I would use a small amount, then keep adding small amounts until I could measure a steady decline. As I approached my target level I would start removing small amounts of GFO, slowing the rate of PO4 reduction. I did a lot of PO4 tests. The process has worked twice for me without a PO4 rebound. Both times it took weeks.

I don’t know if that is helpful but figured I’d share.

 

[Randy Holmes-Farley Verified Community Expert]

I don’t have any suggestions of what to do to help this current situation, but I’d reiterate the desire to make phosphate changes very slowly. Aside from Rishma’s method, just using very small amounts of daily lanthanum would work.

 

[jrmailo]

IME, there’s no quick fix for the kind of situation you’re dealing with. I’ve personally been in the exact same boat and ended up losing almost all the acros in my tank.

The only way I found to recover was to keep things as stable as possible and let the corals slowly bounce back on their own. Any kind of adjustment during this time just made things worse.

If you’ve already found the sweet spot where PO4 is balanced with LaCl, then stick with it—and keep a close eye on things so phosphate doesn’t drop too much in a single day. IMO, when we change PO4 levels too quickly, it causes a shift in the microbial population, and that stresses the acros out big time.

Hang in there—stability is your best friend right now.

How did you ended up stabilizing the yo-yo effect? What method has worked for you?

Since hourly dosing 24 hours a day hasn't worked for me, I am experimenting by changing the dosing method to few large doses per day in hope that this will create a pronounced PO4 gradient between the substrate and the water column. Maybe this will prevent the rocks and sand from getting saturated... we will see in a few days...

 

[Curiousbranching]

How did you ended up stabilizing the yo-yo effect? What method has worked for you?

Since hourly dosing 24 hours a day hasn't worked for me, I am experimenting by changing the dosing method to few large doses per day in hope that this will create a pronounced PO4 gradient between the substrate and the water column. Maybe this will prevent the rocks and sand from getting saturated... we will see in a few days...

I’ve been dosing LaCl in multiple small doses throughout the day and testing PO4 daily to monitor how it responds to the dosage. If I notice that PO4 stays the same or starts to increase, I’ll bump up the LaCl dose until I reach a point where PO4 is gradually decreasing—very slowly.

At the time my tank ran into trouble, PO4 was around 0.5 ppm, and I was only bringing it down by about 0.01–0.02 ppm per day, even though the amount of LaCl I was dosing should have been enough to reduce it by 0.12 ppm PO4. I feed my fish quite heavily, so that might explain why PO4 was dropping so slowly.

 

[jrmailo]

I am really sorry to read this.

I too have battled the phosphate yo-yo as you describe. I have never used LC, so I cannot comment on that method.

More recently I have been able to avoid this yo-yo when reducing phosphates by changing how I used GFO. Basically I would use a small amount, then keep adding small amounts until I could measure a steady decline. As I approached my target level I would start removing small amounts of GFO, slowing the rate of PO4 reduction. I did a lot of PO4 tests. The process has worked twice for me without a PO4 rebound. Both times it took weeks.

I don’t know if that is helpful but figured I’d share.

I was thinking about moving toward GFO if all else fails. Did you run the GFO in a dedicated reactor or in a bag in the sump?

 

[jrmailo]

I’ve been dosing LaCl in multiple small doses throughout the day and testing PO4 daily to monitor how it responds to the dosage. If I notice that PO4 stays the same or starts to increase, I’ll bump up the LaCl dose until I reach a point where PO4 is gradually decreasing—very slowly.

At the time my tank ran into trouble, PO4 was around 0.5 ppm, and I was only bringing it down by about 0.01–0.02 ppm per day, even though the amount of LaCl I was dosing should have been enough to reduce it by 0.12 ppm PO4. I feed my fish quite heavily, so that might explain why PO4 was dropping so slowly.

Around 0.5ppm was the limit for me too it seems. At 0.48ppm, stuff went from pale and unhealthy to full blown RTN.

 

[Curiousbranching]

Around 0.5ppm was the limit for me too it seems. At 0.48ppm, stuff went from pale and unhealthy to full blown RTN.

Oh actually, I’ve used to run PO4 at around 1 ppm —and honestly, the acros were totally fine. I guess it’s the sudden changes that really cause the problems.

 

[Randy Holmes-Farley Verified Community Expert]

Since hourly dosing 24 hours a day hasn't worked for me, I am experimenting by changing the dosing method to few large doses per day in hope that this will create a pronounced PO4 gradient between the substrate and the water column. Maybe this will prevent the rocks and sand from getting saturated... we will see in a few days...

That does not seem like a useful change relative to continuous dosing. Just dosing more, continuously, will do the trick.

 

[jrmailo]

I don’t have any suggestions of what to do to help this current situation, but I’d reiterate the desire to make phosphate changes very slowly. Aside from Rishma’s method, just using very small amounts of daily lanthanum would work.

How do aragonite surfaces interact with PO4?

Interestingly enough, I notice a trend where once my rocks and sand became saturated, the first few doses of LaCl would actually INCREASE the PO4 Level. It would then take a few more doses before the PO4 level drop gradually. I though it might had been due to testing error but even with repeated testing, this trend has been so consistent each time my PO4 rebound that I am curious if there are more to it.

For example, on my last rebound, my PO4 read 0.41 ppm by Hanna ULR
one large does of LaCl and 20 minutes later and my PO4 read 0.45ppm
It took a few more large doses to bring PO4 down.

I was wondering if the reduction in free PO4 in the water column could disrupt the structure of bound PO4 in aragonite and trigger a big release.

 

[Randy Holmes-Farley Verified Community Expert]

Calcium carbonate binds phosphate to make something like calcium phosphate on the surface.

I suspect the boost you see is lanthanum phosphate suspended in the water, dissolving in the acid of the test kit and appearing as dissolved phosphate.

 

[jrmailo]

Oh actually, I’ve used to run PO4 at around 1 ppm —and honestly, the acros were totally fine. I guess it’s the sudden changes that really cause the problems.

I see, so this supports that its most likely the changes are most likely the culprit.

How long did it take for you to acclimate your acro to such level? Did you lose any on the way? And did 1ppm makes it difficult to keep new frags?