Cycling Dry Rock and Leaching Phosphates

[clos1745]

I have about 40 lbs of previously used, and dried rock from from a reefer on Craigslist. It was fairly "clean" looking - at least it did not have tons of obvious dead organic material (no clumps of dried algae or any thing). I am cycling it in a Rubbermaid tub with a couple chunks of LR from my current tanks, a heater and a couple powerheads while I set up my new tank.

I started the process mid-January and I have been monitoring phosphate (with a Hanna ULR phosphorus checker) , ammonia (API kit) and nitrates (salifert kit). I have dosed with Ammonia a few times to 3-4 ppm and within 24hr ammonia was down to undetectable levels, so I am pretty confident the bacteria is established. I think the rock is cycled, but there is still phosphates present.

I have done a few 100% water changes with salt water from the LFS and the phosphates have reduced somewhat each time, but they are not going down very much.

See the attached image for the plot of PO4 vs time.

Unsurprisingly, 24 hours after the first 100% water change (on 1/28/15) PO4 was above the range for the phosphorus checker ( >200 ppb P or >0.6 ppm PO4).

After the 2nd 100% water change on 2/13/15 PO4 was ~0.46ppm and stayed relatively constant for 2 weeks. I thought maybe there was no more PO4 leaching since PO4 didn't continue to climb up.

The 3rd 100% water change was on 2/27/15, and 24hrs later PO4 was back up to 0.36 ppm! So obviously there is still phosphates leaching out of the rock.

SO I have a couple questions:

1) When we say phospates are leaching from the rock - is it just coming from old algae and other organics on the rock breaking down, or is it really coming out of the rock?

2) Any suggestions on what I should be doing to get rid of the phosphates? Do I just need to keep up my procedure of water changes? Should I be using GFO or something else (LaCl etc) to soak it up? Seems like a lower concentration in the water will speed up leaching out of the rock (diffusion gradients and all that), but maybe it doesn't matter if there is some PO4 in the water.

3) How often should I be doing water changes? I have been doing them every 2-3 weeks.

4) How long should I expect it to take for PO4 to drop? I don't mind being patient, but at this rate it is going to take several more months to get PO4 down. Since I am already like 7 weeks into the process, that seems like a long time!

5) Should I continue to dose ammonia (in small amounts) to keep the bacteria "fed," or is the ammonia dosing just a way to test if the cycle is complete and it should be ok to leave until I am ready to set up the new tank and add fish.


Thanks so much for the help!

[kenpau]

I'd ditch the Ammonia and use Lanthium Chloride, I used this to cycle my dead rock which was leaching phosphates big time.
I put a pump in saltwater with the rock for 3 days and my first phosphate reading was 1.35. After a water change and an additional 3 days the reading was 0.92. Then with no water change I added 7.5ml of Lanthanum Chloride to 1.5L of RO water and dripped into the container of rock for about 24 hours until the 1.5L mix was gone, after this phosphates measured 0.08. I kept changing water and testing every 2 days for the next week and repeated the Lanth dosing, after this my phosphates read 0.02, good enough.
You need to use a filter sock with this ideally, I used filter floss and dripped straight into the water.
My tank has been going 8 weeks now and phosphates are at 0.03, although I am using the Zeovit method.
Give Lanth a go though, it definitely worked for me.

[tkeracer619]

Check this thread out, about midway through I do the same process for old rock out of dead tanks...
http://reefcentral.com/forums/showthread.php?t=2145395

[PhaneSoul]

I would just continue what your doing. Siphon out detritus and vacuum the sandbed. I have a few rocks purging nutrients as well and this is what I clean out of my 10g tank every week.

If left in your tank to rot it will just release the nutrients back into your tank.

Lanthium chloride will help to get some out but I highly doubt it will penetrate very far into the surface of the rock. The process I'm describing utilizes the bacteria to get what's inside the rock.. Your still going to be looking at a few months tho. I would suggest temporarily removing your sandbed so detritus is easier to take out (there will be a ton of it) and won't have a chance to breakdown and renter the water column.

[tkeracer619]

If phosphate is deep in the rock it likely won't ever fully be released and it isn't a good choice for reef tanks. The phosphates we are concerned with as I understand it are relatively close the surface of the rock. Which has been backed up by Muriatic Acid baths.

Cooking rock which needs to be done in an environment void of all light is a great way to cure rock, it is however nowhere close to the rate of phosphate removal as LC is. I am not sure if this is what PhaneSoul is refereeing to as the other posts I found were pretty vague in the whole process they are using. Sucking out detritus is good husbandry however.
I've done it many different ways over the years, including the proper cooking method. Water changes are mostly irrelevant when trying to export phosphate, they obviously do but only in limited amounts. Since you already have everything in a tub LC is probably the easiest, cheapest, and labor free way to remove the phosphates.

A good read
http://reefkeeping.com/issues/2006-09/rhf/

[clos1745]

Hi everyone, thanks for all the advice. I'll do some more reading on LC and see if that helps! PhaneSoul- I am curing the rock in a tub there is no sand, but ill try to get any detritus out when I change the water next time.

[PhaneSoul]

Racer there are a few things that I find not to be accurate. It is quite possible to get the phosphates from deep within a rock. Autotrophic bacteria work on cleaning out the rock of available nutrients.
http://libres.uncg.edu/ir/uncw/f/gills2006-1.pdf
I know just a little about treating with LC but my guess is it won't penetrate the rock as deep as bacteria will. Although from what I've seen it looks like a good, cheap way to treat rocks for a minimal nutrient load when starting a tank, but the best, I would beg to differ.

While providing the darkest place possible when cooking rock, it is not required. It can be done with lights and livestock as well, the only difference is you will have to manually remove algae and it may take longer since the bacteria have the option of getting nutrients from the water or the rock, keeping a clean tan will force them to keep to the rock.

In that article macro algae is listed as the number one way to export phosphate and bacteria listed as #2. While this may have truth in a carbon dosing based system where heterotrophic bacteria are the dominant species as the bacterial flock are the main biomass of nitrogen, it is not for an autotrophic bacteria dominant system as the bacteria flock are the main biomass of phosphates.

Point being, heterotrophs are good for binding with nitrogen for removal and autotrophic for phosphates.

[tkeracer619]

I have cured rock in open vats tons of times, the end result is the same but the time to get there isn't. There are faster ways but i'm not sure there are easier than LC. I didn't say it was the best, that is for each individual to decide.

You're link is interesting, I will read it when I have more time. I brushed over it and didn't see anything that jumped out at me about what I was referencing. Most of the phosphate we are concerned about is caused from the die off that occurs after collection or when rock is left out to dry after a crash. This seems to be in the outside layer of rock that is in contact with water.

Taken from the archives from a post in 2004. These are the instructions for "cooking" live rock. There are many variations of the method. I tried to see from your posts what you were exactly doing and couldn't find any details as most of the posts are rather vague. Don't think I am disagreeing with you, I have done it many times over and will do it again if I feel the situation warrants it.

Originally Posted by SeanT

Dave,
Sure thing.
But before I do I just want to say that Bomber instructed me how to do it several months ago and it works great. So it is his process that I am trying to make popular and cause fellow hobbyists a lot less heartache in the long term.
The purpose of "cooking" your rocks is to have tha bacteria consume all (or as much) organic material and PO4 stored on, and in, the rock as possible.

The first step to this is commitment.
You have to be willing to remove your rock from the tank.
It doesn't have to be all at once, but I feel if you are going to do this do it all. In stages if that is easier but make sure that all of it gets done.

The new environment you are creating for your rock is to take it from an algal driven to a bacterial driven system.
In order to this, the rock needs to be in total darkness to retard and eventually kill the algae's on the rock and to give the bacteria time to do the job.

So basically you need tubs to hold the rock.

Equipment needed.
1. Dedication.
2. Tubs to cook rock in. And an equal amount of tubs to hold the rock during waterchanges.
3. A few powerheads.
4. Plenty of buckets.
5. A smug feeling of superiority that you are taking it to "the next level."

Here are the steps, if you have any questions I will try my best to answer them. What I don't know I am sure Bomber can/will instruct.

1. Get into your head and accept the fact you will be making lots of salt water if you aren't lucky enough to have access to filtered NSW.
2. Explain to significant other what is going on so they don't flip out. This process can take up to 2 months. Prepare them in advance so he/she can mark it on the calendar and that they won't nag about it until that date arrives.
3. Setup a tub(s) where the rock is to be cooked. Garages are great for this.
4. Make up enough water to fill tub(s) about halfway and around 5-7 buckets about 60% full.
5. Remove all the rock you want to cook at this stage. (The rock can be removed piece by piece until you are done.) I suggest shutting off the circulation beforehand to minimize dust storms.
6. Take the first piece of rock and dunk it, swish it, very, very well in the first bucket. Then do it again in the 2nd bucket, then the third.
7. Place rock in the tub.
8. Repeat steps 6 & 7 to every piece of rock you want to cook at this time. The reason I suggested 5-7 buckets of water will be evident quickly...as the water quickly turnsq brown.
9. Place powerhead(s) in the tub and plug in. Position at least one powerhead so that it agitates the surface of the water pretty well. This is to keep the water oxygenated. You can use an air pump for additional oxygenation if you wish.
9. Cover the tub. Remember, we want total darkness.
10. Empty out buckets, restart circulation on main tank.
11. Wait.
12. During the first couple of weeks it is recommended to do a swishing and dunking of the rocks twice a week.
What this entails is to make up enough water to fill up those buckets and the tub the rock is in.
First, lay out your empty tub(s) and fill buckets the same as before.
Then, uncover tub with the rock in it. Take a rock and swish it in the tub it's in to knock any easy to get off junk.
Then, swish it thru the 3 buckets again, and place in the empty tub..
Repeat for all your rocks.
Then empty the tub that all the rocks were cooking in, take it outside and rinse it out with a hose.
Place tub back where it was, fill with new saltwater, add rocks and powerheads, and cover.
Wait again unti the next water change.
You will be utterly amazed at how much sand, silt, detrius is at the bottom of the tub and every bucket. It is amazing.

How it works:


Some FAQ's.
When re-introducing the rock to my tank, a month or two from now, should I do that in parts to help minimize any cycling effect(s)...if there are any?
I never have. Really after a very short while, the ammonium cycle has been extablished. That's not what you're worry about though, it's the stored phosphates and that you have to wait it out.
When they are producing very little detritus - you'll know - then I would use them all at once.

Would running Carbon filtration and/or a PO4 reducing media help/hurry/hinder the process?
I wouldn't fool with it. You don't want the detritus to sit there long enough to rot, release water soluble P again. You want to take it out while it's still locked up in that bacterial detritus.




I hope this helps you out.
It really is a "miracle" and a low cost one at that.
The only monies spent are for salt and electricity for the powerheads which are nominal. Especially to rid yourself of Bryopsis.
Time and effort is all it akes. And really not that much effort.
I would say that 85% of my exposed rock had Bryopsis (hair algae) covering it.
There isn't a single visible strand on andy rocks in the tubs now.
Remember, the key is patience. Let this process run its course.

And a few last minute tidbits I remembered.
Your coralline will die back, receed etc.
My thoughts on this are GREAT!
Now my rock is more porous for additional pods, mysids, worms etc.
Coralline will grow back.
Throughout this process the sponges, and pods on my rock have not died off.
Everytime I do a waterchange they are there and plentiful.

If you have any questions please ask.

[PhaneSoul]

Yes that's pretty much the process I follow, a bit more extensive then what I describe, except it usually takes longer then 2 months, moreso on the side of 3-4.

While most P we are concerned about is surface P, but with rock that comes from lagoons and mined from the earth (and those poorly maintained tanks) they total P inside the rock can be troublesome.

We can agree to agree lol, they are all good methods, but in the end, personally I would go the length to make sure any P I could get out, gets out

[Dan_P]

Originally Posted by clos1745

1) When we say phospates are leaching from the rock - is it just coming from old algae and other organics on the rock breaking down, or is it really coming out of the rock?

I appreciated your data plot. It does seem to show that the phosphate is declining.

If phosphate was coming from the bacterial decomposition of organic matter, you would likely see a rising level. You have a declining trend that seems to gone down a little after every water change. What is happening is that after every water change the phosphate adsorbed on the rock is reequilibrating, coming off the rock until the concentration in the water balances what is on the rock. This could go on for ages!

Use GFO to bind the phosphate and force it to continually bleed of the rocks. What you are likely to see initially is a rapid drop to some low level which will then gradually go to zero.

2) Any suggestions on what I should be doing to get rid of the phosphates? Do I just need to keep up my procedure of water changes? Should I be using GFO or something else (LaCl etc) to soak it up? Seems like a lower concentration in the water will speed up leaching out of the rock (diffusion gradients and all that), but maybe it doesn't matter if there is some PO4 in the water.

You are on target. You need to remove the phosphate in the water to speed up the diffusion and then not allow it to equilibrate with the rock again.

3) How often should I be doing water changes? I have been doing them every 2-3 weeks.

You will not need to change the water if you are using GFO and nothing is dying off.

4) How long should I expect it to take for PO4 to drop? I don't mind being patient, but at this rate it is going to take several more months to get PO4 down. Since I am already like 7 weeks into the process, that seems like a long time!

Any phosphate in the water should be removed in hours, 24 maximum. How long it takes most of the phosphate to diffuse out is difficult to answer. Diffusion is a slow process, like hours to move a centimeter. I will bet you could have the phosphate down in a couple weeks.

Since uou are not afraid of data, plotting the concentration over time will inform you when you are reaching the point of diminishing returns. Just keep the GFO fresh. 1 Kg soaks up 25 g of phosphate.

5) Should I continue to dose ammonia (in small amounts) to keep the bacteria "fed," or is the ammonia dosing just a way to test if the cycle is complete and it should be ok to leave until I am ready to set up the new tank and add fish.

You could keep the ammonia dosing going. It won't hurt anything and could beneficial.

[CStrickland]

Dan_P do you have a link to something I can read about this equilibrium?
I thought that the carbonate structures bound and released phos differently than that. I only have the broad strokes, but I thought it was leached by the bacteria sort of choosing a source of nutrients, rather than the typical diffusion toward equal concentrations in a solution?

Thanks!

[Reefin' Dude]

what? confused on why calcium carbonate is a phosphate binder except in SW systems, where it just diffuses because we want it to.

shall we have a reference race?

G~

[CStrickland]

Originally Posted by Reefin' Dude

what? confused on why calcium carbonate is a phosphate binder except in SW systems, where it just diffuses because we want it to.

shall we have a reference race?

G~

No sponge. Lego.

[Reefin' Dude]

no lego. mine!!

you didn't say the magic pH.

G~

[CStrickland]

Haha, ok I'll play. Mark, set, go!
I'm working mostly with this:[Gill, S. "Phosphorus Liberation by Aquatic Microorganisms" 2006] it's an easy read that covers a lot of bases. Races are fun when you put puzzle pieces together from many sources, but it's a treat when one paper has so much of what I'm after.

The P associated with carbonates is incorporated in the mineral matrix, not just surface adsorbed. As such the liberation of P from such sources requires the dissolution of the matrix to take place and is not achieved simply through changes to redox potential.

~ so not the electron transfer sort of equilibrium that you might think. Although I have been reading some interesting things about redox potential in dsb's and plenums, but I think that is a phos-O2 bunnyhole that I'm going to circle back to when I run out of light reading.

The principal factor driving P liberation was acidity. The concentration of [H+] ions increased rapidly in the systems where microorganisms were present. ...
The remainder of the P liberation was likely brought about by the action of OAs (organic acids - CS) produced by the microorganisms in the system.

~ bacteria population respiration increases acidity at the substrate directly by adding ions, and overall by releasing acid. This acid dissolves the matrix binding the phos to the carbon so the hungry bacteria can eat it.

When no P substrate was included no bio-production was observed, as compared to systems that incorporated some form of refractory P substrate where an appreciable level of bio- production was observed. Furthermore when an identical system was incubated with no biological influence, insignificant concentrations of P were detected

~ P availability limits biofilter / biofilter limits P availability.

So...
Phos doesn't just leak out the rock like a sponge, it has to be broken off like a lego by the right bacteria. This happens when the calcium carbonate is acidified by the bacteria on its surface, as they use phos for their atp. This does not happen when the bacteria are not around, or not hungry. But they don't use all of it, and the scraps are measurable by these scientists, and they feed the algae.
Makes sense to me.

[clos1745]

Dan_P thanks for the replies to all of my questions. I think you are right that I need to keep the PO4 concentration in the water low so it will keep driving the phosphates out of the rock.


Strickland, thanks for the reference. Looks like an interesting read.

[CStrickland]

You're welcome Clos.

PS ahahahaha! I just realized I posted the same link Phane did like 8 posts ago
I do not think this is a race I will win, but I very much enjoy limping around the same track as you guys

[PhaneSoul]

Originally Posted by CStrickland

Haha, ok I'll play. Mark, set, go!
I'm working mostly with this:[Gill, S. "Phosphorus Liberation by Aquatic Microorganisms" 2006] it's an easy read that covers a lot of bases. Races are fun when you put puzzle pieces together from many sources, but it's a treat when one paper has so much of what I'm after.

Might be easy for you guys, the only thing i understood when G showed me this article months ago was..... (bold is what i added)


So...
Phos doesn't just leak out the rock like a sponge, it has to be broken off like a lego by the right bacteria. This happens when the calcium carbonate is acidified by the bacteria on its surface, as they use phos for their something scientificy. This does not happen when the bacteria are not around, or not hungry. But they don't use all of it, and the scraps are measurable by these scientists, and they feed the algae.
Makes sense to me.

Originally Posted by clos1745

Dan_P thanks for the replies to all of my questions. I think you are right that I need to keep the PO4 concentration in the water low so it will keep driving the phosphates out of the rock.


Strickland, thanks for the reference. Looks like an interesting read.

not only do you need to keep the concentration low, you also need to clean up the detritus or else it will just rot and release inorganic p back into the water column. you will come to a plateau where inorganic phos levels out for a bit. if by this time your still not cleaning then that plateau pattern will break and inorganic phos will start going back up because the detritus is piling up and rotting and releasing inorganic p at a rate faster then can be bound with gfo and the liverock.

[Dan_P]

Originally Posted by CStrickland

Dan_P do you have a link to something I can read about this equilibrium?
I thought that the carbonate structures bound and released phos differently than that. I only have the broad strokes, but I thought it was leached by the bacteria sort of choosing a source of nutrients, rather than the typical diffusion toward equal concentrations in a solution?

Thanks!

Here is a nice slide show explaining the reversible attraction of phosphate and aragonite. Select "PO4 and Carbonate" on left hand side of page.

http://yyy.rsmas.miami.edu/groups/jmc/fla-bay/fbay.html

This phenomenon tends to be more important for finer grain sand than larger grain. Scientific studies do not discuss this reversible adsorption with reference to live rock but being aragonite and being a porous structure, it does not seem unreasonable to use the desorption and equilibrium notion.

I used fresh aragonite sand as a phosphate adsorber in my set up as an experiment. It does indeed adsorb phosphate but the capacity is smaller than GFO.

Yes, bacteria and I think algae have an extracellular enzyme that can scavange phosphate but this tends to end up in biomass not floating around in the water. Also, your water data is not so easily explained by bacterial action as it is desorption.

Here is a fun fact. Aragonite also binds dissolved organic compounds. I found this out after looking for information on the adsorption of methylene blue by aragonite. So, when you see innocent looking white sand in your aquarium, it is really a complex chemistry experiment in progress :-)

[CStrickland]

Haha, my sand is far from innocent. Devious ole mistress she is!
I'll have a look at the info in a bit, kind of a busy day. But if anyone wants to play along and read the paper, you can do so here: [Millero, F. 2001 "Adsorbtion and Desorbtion of Phosphate on Calcite and Aragonite in Seawater"]

Phane- you know what ATP is, we did that with a nardface like a month ago, remember? Phos is life? I've got a funny feeling that it plays into the auto / hetero distinction in carbon dosing that makes my eyes glaze over when you natter on about it, and I reckon you'd like "sciency stuff" more than you think if you tried it. Same with tofurkey

[Dan_P]

Originally Posted by CStrickland

Haha, my sand is far from innocent. Devious ole mistress she is!
I'll have a look at the info in a bit, kind of a busy day. But if anyone wants to play along and read the paper, you can do so here: [Millero, F. 2001 "Adsorbtion and Desorbtion of Phosphate on Calcite and Aragonite in Seawater"]

Phane- you know what ATP is, we did that with a nardface like a month ago, remember? Phos is life? I've got a funny feeling that it plays into the auto / hetero distinction in carbon dosing that makes my eyes glaze over when you natter on about it, and I reckon you'd like "sciency stuff" more than you think if you tried it. Same with tofurkey

Thanks!

I see that bicarbonate decreases phosphate binding. When nitrate is reduced, it liberates bicarbonate, which locally could liberate phosphates. This would possibly result in the nitrate level going down while phosphate level going up. Much to ponder here!

[PhaneSoul]

Where are the phosphates going? By 'phos level going up' where are they going? Into the water column as inorganic or bound in the bacterial biomass? Where does the biomass go?

Once those two questions are answered is when we can put in place a export plan for phos.

[reefgeezer]

Originally Posted by clos1745

1) When we say phospates are leaching from the rock - is it just coming from old algae and other organics on the rock breaking down, or is it really coming out of the rock?

Mostly from the rock. The phosphates are loosely bound in the calcium carbonate based substrate that makes up the rock. It is mostly on the surfaces of the rock which includes the inner surfaces or pores of the rock. The phosphates are not strongly bound and will "leach" into the water until a point where equilibrium is reached. When the phosphate level is lowered in the water column by large water changes, GFO, LaCl, or algae/bacteria uptake more bound phosphate is leached until equilibrium is reached again. This cycle occurs until the bound phosphate in the rock is very low.

Originally Posted by clos1745

2) Any suggestions on what I should be doing to get rid of the phosphates?

LaCL would be the most effective method. It works by binding the phosphate in the water column and precipitating it out. It can work pretty quickly. However, the phosphate doesn't leach as quickly as the LACl removes it. You'll need to repeat this process several times over many weeks to render the rock almost phosphate free.

Originally Posted by clos1745

3) How often should I be doing water changes?

By now I'd think water changes wouldn't be necessary. BTW, are you sure the LFS water is phosphate free?

Originally Posted by clos1745

4) How long should I expect it to take for PO4 to drop? I don't mind being patient, but at this rate it is going to take several more months to get PO4 down. Since I am already like 7 weeks into the process, that seems like a long time!

It really depends on the level of phosphate bound in the rock, the amount of phosphate released by biological processes, and how far you keep the phosphate levels in the water column below equilibrium level.

Originally Posted by clos1745

5) Should I continue to dose ammonia (in small amounts) to keep the bacteria "fed," or is the ammonia dosing just a way to test if the cycle is complete and it should be ok to leave until I am ready to set up the new tank and add fish.

I'd stop dosing ammonia. Maybe add a little flake food once a week.

[Reefin' Dude]

Originally Posted by reefgeezer

Mostly from the rock. The phosphates are loosely bound in the calcium carbonate based substrate that makes up the rock. It is mostly on the surfaces of the rock which includes the inner surfaces or pores of the rock. The phosphates are not strongly bound and will "leach" into the water until a point where equilibrium is reached. When the phosphate level is lowered in the water column by large water changes, GFO, LaCl, or algae/bacteria uptake more bound phosphate is leached until equilibrium is reached again. This cycle occurs until the bound phosphate in the rock is very low.

do you have references to support this, other than in hobby literature?

this says otherwise.

Calcium carbonate binds PO4 and latter releases it?

Calcium carbonate phosphate reaction?

Adsorption of Phosphate on Calcium Carbonate

Calcium Carbonate Phosphate Binding Ion Exchange Filtration and Accelerated Denitrification Improve Public Health Standards and Combat Eutrophication in Aquatic Ecosystems

Uptake of phosphate ions by calcium carbonate

the only references i have read about what you are saying is in the hobby literature, where they tend to ignore the role bacteria play in this.

G~

[reefgeezer]

Originally Posted by Reefin' Dude

do you have references to support this, other than in hobby literature?

Nope. This is a hobby forum.