Phosphate Absorption Rates in Aragonite

[ZaneTer]

Thank you so much

That is a far better answer than I had hoped for. This could be a very useful tool for those with excess PO4. That being said it could also be a potential disaster if people added aragonite to a “dirty” tank and rapidly stripped the water of excess PO4.

 

[jda]

Since the aragonite binds only to an "equilibrium" it will always leave some in the tank. Even at low levels, it can never take you low enough to kill coral and not likely ever low enough to even limit growth.

My own personal thoughts are that more people do not know about this and it hids/masks issues with their tanks. When the tank level gets so high that they have problems, they have years of neglect to deal with.

 

[ZaneTer]

I still believe you are mistaken and that it is extremely easy to strip a tank of PO4 to the point of causing coral death. Your point would rely on people having neglected their tanks for a period that would allow PO4 to build up and bind to the aragonite. Even then it will require some effort but it’s quite easy to remove even that just with a reasonable size ball of chaeto.

 

[ZaneTer]

If you were correct, and you may be, then nobody would ever have to dose PO4.

 

[jda]

Dosing P was not a thing until a year or two ago. I am not saying that is never needed by nobody, but it probably is not needed for the vast majority of people who do it. I do not want to argue this with you again... this happens every few months and then a few months after that the people who were all up in arms about lower N and P being deadly change their minds like so many before them. I just try and help. If you don't want to believe it, then don't and I will try and help other people. I will say this one last time... unless you are driving N and P artificially low with media or chemicals, there is next to no chance that you do not have enough... something else is going on in your tank. In most cases, the tank is usually just new and needs to mature... and dosing it sets them back by not letting the natural equilibrium establish, but some do not want to hear this.

I constantly measure 1 to 3 ppb on the Hannah ultra low and my stuff grows like crazy and I even have some cyano in a few places in the tank. There is plenty of P in there driving and consuming the equilibrium. This is where you want to get with a high volume equilibrium, but it is better if the tank figures this out instead of you.

I can take gallons and gallons of GFO to rid tanks of some terrestrial P that was bound in dry rock. I had a friend who bought 100 pounds and it took him 6 gallons over many months to get it to a reasonable level. He did not believe me since the "BRS Video on Dry Rock did not mention bound phosphates" - this was an actual conversation that we had. He does now. Do not underestimate how much can be in there. Some of it seems fine with only minor issues, but some of it ruins tanks for people.

 

[jda]

Also, don't be fooled and think that a lot of the P that you dose is not just immediately bound by aragonite. There is little double that the living organisms will get some, but the rock and sand will too.

 

[mcarroll]

Rock that I have gotten from the pacific has very little phosphate bound in it. How could it have much? ...the water has such a low level.

I agree with your point that aragonite could potentially maintain 1-5 ppb. But just to quibble with details...

Generalizing "the pacific as low nutrient" seems problematic (even if true) when you're talking about specific rock that's not actually in the pacific.

Wouldn't the condition of the rock logically be dependent on the conditions under which the rock was collected and held before use. That may or may not relate to what the water conditions were like at the rock's origin. For one thing, it doesn't account for how the rock may or may not have been cleaned in between collection and use.

This experiment says "yes, it is definitely possible for aragonite to hold (and release) a lot of phosphate" under the conditions of the test.

That was the question we asked, so it was a great experiment and a great answer.

So phosphate leeching/adsorbing definitely happens.

Probably all the time to some extent.

However, the inconsistency that only some folks seem to have "phosphate leeching problems" yet most do not is still not answered by this. Nor are many other questions, like whether there's a way to take advantage of this, as @ZaneTer is suggesting, rather than considering it some kind of liability.

These other aspects weren't the things that were being tested on this thread, after all...no answers to these questions were expected. In fact, nothing reefy (i.e. biological) was significantly involved. So there are bound to be lots more questions about how this works in practice over the lifetime of a reef.

@ZaneTer @chipmunkofdoom2 (and everyone else too) If you're up for it, this calls for more experiments!!

Dosing P was not a thing until a year or two ago.

Low level phosphate testing, carbon dosing and GFO usage are all pretty recent.

Nutrient dosing would naturally be needed after the fact when the mistakes of nutrient removal are realized. So they kinda all go together in my perspective.

Nutrient removal's misuse is usually (in my experience at least) based on the common misconception of an ultra low nutrient reef as being some kind of healthy ideal.

Dosing phosphate or other nutrients at least under conditions I'm familiar with is to get things back to normal - even if that means being bound to aragonite vs direct usage.

 

[jda]

Lets don't quibble too much. This gets people into trouble where they read your whole paragraph and forget about the first sentence. I also agree that we do not have much in the way of science... but nature is pretty clear on this... the rock from the pacific has very low levels of bound phosphate. People do this to Dr. Holmes-Farley all of the time where they miss the "big picture" single phrase and focus on the quibbling that he writes or his sometimes rhetorical questions.

I agree with the recency, also. I also agree that Ultra Low nutrient reefs are tricky, hard and possibly dangerous. I do not think that NSWish reefs are Ultra Low, just Low. Low can happen by natural means - high volume low level equilibrium. Ultra Low requires chemicals and media to drive levels lower than what can be achieved with natural media. I do not advocate Ultra Low to anybody but the best of the best. Low is no issue to anybody.

 

[mcarroll]

Lets don't quibble too much.

This may be out of our control.

I was gonna ask if you'd mind updating the first post with a clear explanation of the test as it was actually performed and the literal findings so all that isn't lost in the rest of the discussion?

(I'd even kinda like the post to be locked with a link to another thread for continuing discussion...but that's just me.)

 

[chipmunkofdoom2]

IMO this would be a good BRS TV Investigates. They could follow the procedure established by @jda to confirming the initial findings, then they could also take it a step further and find out how quickly the phosphates are released back into the water after the rock is dosed to saturation. Perhaps recording how many water changes it would take, which would be a good advertisement for phosphate-binding media like GFO. What are your thoughts? @randyBRS @Bulk Reef Supply @Ryanbrs

I agree with @jda though. Regardless of the nuance, we've suspected for a while that aragonite rock can indeed bind phosphates, and this experiment corroborates that. There's likely a lot more going on here than we know, but we've at least demonstrated that aragonite rock can bind a substantial amount of phosphate.

 

[jda]

This may be out of our control.

Touche. I cannot edit a post that old.

IMO this would be a good BRS TV Investigates... which would be a good advertisement for phosphate-binding media like GFO. What are your thoughts?.

I would first like them to analyze a whole bunch of their rock and figure out how much Phosphate that it has in it... then estimate the amount of media needed to get it to where it would be if people purchased real live rock from the Pacific. This could be a total cost-of-ownership thing. Dry rock is not always as cheap as it seems.

This may be out of our control.

That last tangent was totally in my control and I went right down that road anyway...

 

[bubbaque]

Is it possible that the rock and sand absorb it faster than corals use it? Kind of like if I set a dry sponge on a small puddle of water. The sponge holds all the liquid and doesn't allow any out?

 

[Randy Holmes-Farley Verified Community Expert]

Is it possible that the rock and sand absorb it faster than corals use it? Kind of like if I set a dry sponge on a small puddle of water. The sponge holds all the liquid and doesn't allow any out?

It reversibly binds, so it will come back off as the phosphate level in the water declines.

 

[bubbaque]

It reversibly binds, so it will come back off as the phosphate level in the water declines.

Thanks for the help! I remember dosing phosphate from 0 to .04 and it would be back to 0 in less than a day. I could not understand what was happening. This thread helped me understand now.

 

[jda]

Another semi-related tangent: this is why you should change media when you change water (GFO, AlOxide, etc.). The media will release phosphates back into the tank after the water change dropped the levels a bit.

 

[mcarroll]

Touche. I cannot edit a post that old.

Really? You can definitely report the post and an editor will happily apply any changes for you.

(I know there's a way for you to have access for editing older posts too.....don't recall what it is though as I've been around here long enough to forget! @saltyfilmfolks do you know?)

 

[jda]

After about 15-30 minutes, I cannot edit anything. I am just a scrub without even any badges under my name... the lowest of the low.

 

[Randy Holmes-Farley Verified Community Expert]

I can change something if it is important

 

[bubbaque]

Really? You can definitely report the post and an editor will happily apply any changes for you.

(I know there's a way for you to have access for editing older posts too.....don't recall what it is though as I've been around here long enough to forget! @saltyfilmfolks do you know?)

Need to be site supporter or the time limit is 30 minutes to edit.

 

[ZaneTer]

@mcarroll
Yes I would be keen to participate. What sort of experiments were you thinking of us performing?

My tank is about 5 years old. It is bare bottomed and was created with synthetic rock. I have a slimmer and a fuge containing chaeto. I am only home for two weeks in every three months so for me low maintenance is top priority. This could explain why I don’t have a problem with excess phosphate. I simply don’t have anything leeching it into my water.

Currently I am dosing trisodium phosphate. I mixed 2 grams into 1 litre of RODI. I dose 4ml of solution each day adding 0.01ppm to my roughly 800 litre setup.

I believe that aragonite could be a fantastic tool for new reefers just to help them balance the tank for a while until they develop a better grasp on their tank chemistry.