Pukani Dry Rock Curing/Phosphate Advice?

[markbeta]

I recently purchased 110 lbs of Pukani dry live rock for BRS. I cleaned off all the organic material I could see and power washed the rock before adding it to a 44 gallon Brute trash can container. I added a heater set to 80F and placed a Rio + 2100 pump (692 GPH) in the bottom of the container with an open path through the rock to the top surface. The water circulation is excellent. I mixed enough RO/DI salt water to fill the container which submerged all the rock with a couple inches to spare (about 35 G). The setup is seen in the following pic:

The rock has been curing for a week now. A couple of days in, the water started to yellow a bit and there was a thin layer of yellow/brown scum around the container, but I added about a cup of activated carbon in a media bag in the high flow area of the container and the water cleared up quickly. I also added a dose of Bio Spira nitrifying bacteria. So far, I have not encountered any foul smelling water that I've read others have experienced.

My goal is to remove all the dead organics from the rock before adding it to my new tank. I am familiar with curing live rock until the nitrate level stops rising, but what I am really interested in is the numerous instances people have with BRS Pukani dry rock leaching a lot of phosphate. I would like to better understand a practical way to get the phosphate out of the rock.

My thought is that keeping the phosphate levels in the water column of the container as low as reasonably possible will create an environment to pull the phosphate out of the rock at an accelerated rate. I believe naturally the organics will want to move from an environment of higher concentration (rock) to lower concentration (water). Does that make sense to anyone with a better understanding of organic chemistry?

I plan on keeping the dissolved organics levels low(er) by doing 60% water changes possibly once a week because 60% is what I can do easily with my setup. I will continue down this path until my nitrate and phosphate levels are acceptable. I'm hoping this will take 4-6 weeks. Does this sound reasonable?

As an alternative method, I'm also contemplating dosing SeaKlear Phosphate Remover instead of the frequent water changes. With the active ingredient in the Phosphate Remover being lanthanum chloride (LC), I believe the LC binds to phosphate in the water column and crashes it out of solution into precipitate. I think this essentially creates an environment with lower dissolved phosphate in the water column like a water change and will accelerate the cure.

Any advice/information on the mechanisms of phosphate removal of dry rock as well as constructive criticism on my thinking and plan would be greatly appreciated.

Currently, my ammonia is zero, nitirite is >1 ppm (test kit max), no reason to test nitrate because of nitirite level, and phosphate is >8.5 ppm (test kit max).

 

[downbeach]

I've bought this rock on three occassions, and found that the easiest way to clean it was with an etching process using some form of acid, i.e. vinegar, or muriatic. Using vinegar will take longer but is somewhat safer to use. In my case I found that if I first removed as much of the dried matter, i.e. serpent stars, sponges, etc., and hydrate the remaining overnight and using a strong water flow from a hose or pressure washer the next day would remove most of the heavier organic matter. Then, I would place the rock in a brute container with the acid. This will disolve some of the surface area of the rock, removing the remaining organic matter and much of the PO4 and other elements that may be attached to the surface of the rock. Once that process was complete, I would rinse again and place the rock in my QT tank(55 gal.) with some freshly made SW, and monitor, do WC's etc., until ready to use.

 

[pdiehm]

I soaked mine in RODI for a week to get a PO4 reading.

MOved it to saltwater. Dosed with SeaKlear (Lanthanum Chloride). Dose...wait a day or 2, check PO4. Dose again....wait a day or 2. Change water. Repeat.

Mine sat in the brute containers for about 3 months. Moved to the tank as I was setting up, and about 8-10 weeks later, my PO4 level tested 0.00. It was routinely at 0.01 or 0.00 prior to setting up the tank. One thing I did NOT want was an algae issue.

 

[markbeta]

It sounds like it takes about 3-5 months for the PO4 to completely diffuse out of the rock while in a saltwater environment with water changes.

I would like to know how quickly an acidic etching of the rock helps to speed up this process of elimination? If the majority of the phosphate is contained in the outer surfaces of the rock, then etching could vastly improve the curing time.

 

[pdiehm]

It sounds like it takes about 3-5 months for the PO4 to completely diffuse out of the rock while in a saltwater environment with water changes.

I would like to know how quickly an acidic etching of the rock helps to speed up this process of elimination? If the majority of the phosphate is contained in the outer surfaces of the rock, then etching could vastly improve the curing time.

probably sooner, but I really liked the look of the rocks, and didn't want to strip off the top layer of the rocks.

 

[undbulsu]

I am just finishing up with @100 lbs of Pukani. One thing I noticed

I am just finishing up with @100 lbs of Pukani. One thing I noticed

I cleaned and cleaned the rock while still dry. Thought I had all organic material removed. Then I cleaned it again while still dry.

After my first week of soaking I took out a few pieces and inspected them in bright sunlight. The water had hydrated a lot of stuff I missed. I then cleaned each rock again.

I got TWO cups of organic material out of the rocks that I had previously cleaned twice.

I guess what I am saying is clean the rock again after it has soaked for a while.

I really think the long term PO4 problems people have is due to hidden organics in the rock and not the rock itself leaching phosphate.

 

[downbeach]

It sounds like it takes about 3-5 months for the PO4 to completely diffuse out of the rock while in a saltwater environment with water changes.

I would like to know how quickly an acidic etching of the rock helps to speed up this process of elimination? If the majority of the phosphate is contained in the outer surfaces of the rock, then etching could vastly improve the curing time.

It varied a bit between the three batches for me, but mine didn't go any longer than two weeks. You can't even notice the amount that has been etched off the surface of the rock, in fact I've etched a couple pieces more than once to help remove some bubble algae that I believe came in on a couple frag plugs. But, the type and strength of the acid and dilution rate of the solution you make up will have an affect on how long, and how much you etch off the rock.

 

[markbeta]

The initial acid etching of dry rock before starting the curing process sounds like a good procedure to perform. I will definitely try it with a future batch of new dry rock, but I am currently committed to curing my new batch without the etching.

So, my question now is whether or not dosing lanthanum chloride (LC) based phosphate remover will actually speed up the curing of the rock. It appears that the LC just precipitates the orthophosphate released from the rock out of the water column, so it clears the water of phosphate, not the rock. Does having lower levels of phosphate in the water column promote the rock to release more phosphate, or is the phosphate release rate only controlled by the die-off of organic material in the rock?

Has anyone cured dry live rock with just time and water changes, but also another batch using time, water changes, and LC dosing to compare the two methods? Does the LC dosing speed up the process of eliminating phosphate release from the rock?

 

[CuzzA]

LC is only going to bind the PO4 from the water which would likely be helpful as well as doing large water changes and running a low micron sock to catch the PO4 that has bound with the LC.

Just to be clear on what Pukani is... This rock is harvested live reef. Make no mistake about it. It was a live reef that was harvested, sat on a beach for a month, quickly pressure washed and then placed on a container and shipped to locations around the world.

The PO4 leaching from this or any other reef rock is from all of the dead organisims. Including coral, sponges, bivalves, crabs, invertebrates and sometimes even fish. This dead tissue is often deep within the coral skeleton and that is why it takes so long. No different than if you killed your full blown reef tank, you would get a spike in PO4.

 

[CStrickland]

So, my question now is whether or not dosing lanthanum chloride (LC) based phosphate remover will actually speed up the curing of the rock. It appears that the LC just precipitates the orthophosphate released from the rock out of the water column, so it clears the water of phosphate, not the rock. Does having lower levels of phosphate in the water column promote the rock to release more phosphate, or is the phosphate release rate only controlled by the die-off of organic material in the rock?

You've pretty much got it. There are two ways people say that phos from whatever the rock is touching before you get it gets attached to the rock. I'll try to break it down, but I have a minimal understanding to begin with, and it's one of those simple things that's kinda hard to explain when you don't know how much info a perrson wants. Sometimes people are just interesting in getting the tank up ASAP, but if you really want to get your head around the processes its endless how much you can read

The first is a stronger bond, whereby the calcium carbonate molecules bind the phos to the chrystal structure. This is supposed to be what happens in the ocean, the tide sweeps the uneaten food out to sea where it becomes part of the bedrock for millennia to later get released into soil (and maybe attach to mined dry rock buried there). Acid breaks that bond, and also the other ones that hold the rock together.

The other is something about the surface of the rock maintaining equilibrium with the surrounding water. I understand that even less, apparently the water-phos cares how much phos is in the rock or vice versa. So they will strive for balance. If that's true then it is a fair assumption that by lowering the water-phos you will "pull" phos from the rocks quicker. You could do this with many expensive wc's or just use lc to precipitate the phos out of the water to make room for more.

I'm not aware of any side-by-side comparisons, it certainly would be nice.

 

[markbeta]

Thanks for much to all of you on this thread who have helped me understand what I am dealing with. I have another question:

When dosing a lanthanum chloride based phosphate remover that precipitates the phosphate out of the water column, does the precipitate need to be removed from the system? More specifically, will the precipitate eventually dissolve back into the water column after a period of time?

I don't have an easy way to export the precipitate due to my Brute trash can being essentially full of rock, and the water changes I perform consist of blindly siphoning water out of the container.

 

[QUASIMOTO]

Pukani phosphate

Pukani phosphate

Just FYI--- I am still having leaching problems 7 months into my setup...

I have some very very large pieces of rock, (one is over 50lbs)-- I used LC for about two weeks, regrettably I didn't have my hanna checker then and I just assumed from threads that after the two weeks I would have been safe, as my water was very clear and the "smell" was gone...

boy do I wish I would have left the rocks to soak longer....

My PO4 is still way too high and after months of water changes and changing out tons of media its still wont go down.

It is however just recently beginning to turn the corner, and my P04 is becoming a little more manageable....

good luck and be very careful with this rock

--QUASI