Reef Central Online Community

Go Back   Reef Central Online Community > General Interest Forums > The Reef Chemistry Forum
Blogs FAQ Calendar Mark Forums Read

Notices

User Tag List

Reply
Thread Tools
Unread 11/03/2014, 02:50 PM   #76
Randy Holmes-Farley
Reef Chemist
 
Randy Holmes-Farley's Avatar
 
Join Date: Apr 2001
Location: Arlington, Massachusetts
Posts: 86,233
Quote:
Originally Posted by shermanator View Post
Someone setup a control tank (like you did in your article) and showed that the filtrate of Phosguard causes problems?

In your article you have a nice, controlled experiment (but I suspect you used Al(III)). When someone posts that they added Phosguard and all hell broke loose, that of course isn't a controlled experiment.

Side note: Advanced Aquarist needs a methods section.
Many people added Phosguard and within hours, leathers closed up.

That was their "test" tank. It happen so often that it was not a one time thing.


__________________
Randy Holmes-Farley

Current Tank Info: 120 mixed reef
Randy Holmes-Farley is offline   Reply With Quote
Unread 11/03/2014, 02:51 PM   #77
dkeller_nc
Registered Member
 
dkeller_nc's Avatar
 
Join Date: Mar 2013
Location: Central NC
Posts: 5,062
Quote:
Originally Posted by shermanator View Post
From a chemistry perspective, I have trouble with the idea that Al2O3 will (again, in a reef tank) ever wind up as ionic Al(III).
That would depend. If it is true that aluminum has some equilibrium solubility in seawater at normal pH and temperature, and if a source of aluminum is present in the system, then from a equilibrium thermodynamics perspective there will be some concentration of aluminum in the water (presumably, at the equilibrium solubility unless the amount of aluminum available to the system is restricted below this amount).

The only asterisk one would have to add to the above supposition is that the rate of dissolution from the solid has to be reasonably non-rate limited.


dkeller_nc is offline   Reply With Quote
Unread 11/03/2014, 02:55 PM   #78
Fade2White12
Registered Member
 
Fade2White12's Avatar
 
Join Date: Oct 2007
Posts: 271
I know that Phosguard has been of great contention between Randy and Seachem over the years. What are the differences in the more recent study by Batten and Lafayette vs. Randy that would lead to such different conclusions? Seachem continues to hold that alumina is not soluble in reef tanks.


Fade2White12 is offline   Reply With Quote
Unread 11/03/2014, 02:58 PM   #79
shermanator
Registered Member
 
Join Date: Feb 2014
Posts: 854
Quote:
Originally Posted by Randy Holmes-Farley View Post
This paper shows that the solubility of corundum (least soluble of all the aluminum oxide hydroxides) at pH 4 is about 10^-3 M or 27 ppm.

Are you really so confident that at pH 8.2, the 0.4 ppm that I observed cannot be dissolved? Pankow ("Aquatic Chemistry Concepts") shows a solubility graph vs pH for all aluminum species, and pH 8.2 the total is lower than at pH 4, but by less than a factor of 100. So I just don't see how 0.4 ppm is out of the question, especially since the surfaces of Phosguard may well be hydrous oxide/hydroxides and not pure corundum (which are more soluble than corundum by far).

http://www.clays.org/journal/archive...6/36-5-391.pdf
I don't know what the solubility curve looks like, but I generally ballpark 10x per pH unit.

And to be clear... I'm not saying that your measurements are wrong. I'm saying that the soluble filtrate you obtained is almost certainly Al2O3 and not ionic Al(III). I make a big distinction from something being "in solution" and something ionic.

I'll tell you what... I have to leave in a few minutes to get my kids -- and I'm giving a couple seminars out of town the remainder of this week, but here is what I will do...

I'll buy some Phosguard (and/or MarinePure Media, which I do have) and dissolve it in 18-ohm water. I'll filter it with both 0.45 µm and 0.2 µm syringe filters. I'll buy an Al(III) spectrophotometric test kit (should be silent for Al2O3, even "dissolved" Al2O3) and post the results. I'll make a student do it.

It'll take me a few weeks. But let's agree to the methods (and a test kit), if possible.



Last edited by shermanator; 11/03/2014 at 03:04 PM.
shermanator is offline   Reply With Quote
Unread 11/03/2014, 02:59 PM   #80
Maximus
Registered Member
 
Maximus's Avatar
 
Join Date: Feb 2001
Location: Monterey County
Posts: 6,442
I wish I understood what you two are talking about!


__________________
This space for rent...

Current Tank Info: 36x36x16 A.G.E. tank. Lighting: ATI Straton. Circulation: 2x Vortech MP40wQd's. Skimmer: Red Sea 300. Controller: Neptune Apex. Doser: Neptune Dos.
Maximus is offline   Reply With Quote
Unread 11/03/2014, 03:00 PM   #81
shermanator
Registered Member
 
Join Date: Feb 2014
Posts: 854
Quote:
Originally Posted by dkeller_nc View Post
That would depend. If it is true that aluminum has some equilibrium solubility in seawater at normal pH and temperature, and if a source of aluminum is present in the system, then from a equilibrium thermodynamics perspective there will be some concentration of aluminum in the water (presumably, at the equilibrium solubility unless the amount of aluminum available to the system is restricted below this amount).

The only asterisk one would have to add to the above supposition is that the rate of dissolution from the solid has to be reasonably non-rate limited.
I never looked up the k-sp, which would be instructive.

But yes, from a thermodynamics point of view, everything is reversible. And from a thermodynamics view, I can walk through a wall, too.


shermanator is offline   Reply With Quote
Unread 11/03/2014, 03:06 PM   #82
shermanator
Registered Member
 
Join Date: Feb 2014
Posts: 854
Quote:
Originally Posted by Randy Holmes-Farley View Post
Many people added Phosguard and within hours, leathers closed up.

That was their "test" tank. It happen so often that it was not a one time thing.
Couldn't an alternative hypothesis be that it was due to rapid phosphate changes? [I know nothing about Phosguard, but a quick google search indicated SeaChem suggests using small amounts at a time.] I'm not arguing that is the cause, but it's at least a possibility, no?


shermanator is offline   Reply With Quote
Unread 11/03/2014, 03:14 PM   #83
Randy Holmes-Farley
Reef Chemist
 
Randy Holmes-Farley's Avatar
 
Join Date: Apr 2001
Location: Arlington, Massachusetts
Posts: 86,233
Quote:
Originally Posted by shermanator View Post
I don't know what the solubility curve looks like, but I generally ballpark 10x per pH unit.

And to be clear... I'm not saying that your measurements are wrong. I'm saying that the soluble filtrate you obtained is almost certainly Al2O3 and not ionic Al(III). I make a big distinction from something being "in solution" and something ionic.

.
Well, I disagree. Read the linked paper before asserting the aluminum oxide is not soluble.

On the solubility vs pH, yes it goes 10x per pH unit for much of the pH range, but solubility is increasing 10x per pH unit above pH 7, where it reached a minimun for aluminum.

I'd just read the article I linked, but if you want to do experiments, go for it!


__________________
Randy Holmes-Farley

Current Tank Info: 120 mixed reef

Last edited by Randy Holmes-Farley; 11/03/2014 at 03:43 PM.
Randy Holmes-Farley is offline   Reply With Quote
Unread 11/03/2014, 03:21 PM   #84
Randy Holmes-Farley
Reef Chemist
 
Randy Holmes-Farley's Avatar
 
Join Date: Apr 2001
Location: Arlington, Massachusetts
Posts: 86,233
Quote:
Originally Posted by Fade2White12 View Post
I know that Phosguard has been of great contention between Randy and Seachem over the years. What are the differences in the more recent study by Batten and Lafayette vs. Randy that would lead to such different conclusions? Seachem continues to hold that alumina is not soluble in reef tanks.
That is an old study they did to try to disprove me.

I addressed it in 2008 and referred to it here, but I do not have the original discussion thred any longer as it is not archived:
http://www.reefcentral.com/forums/sh....php?t=1504036

I'll see if I can remember what their problems were, but as I recall, they did not have an adequately low limit of quantitation to detect what I saw as they used a different method.


__________________
Randy Holmes-Farley

Current Tank Info: 120 mixed reef
Randy Holmes-Farley is offline   Reply With Quote
Unread 11/03/2014, 03:38 PM   #85
Randy Holmes-Farley
Reef Chemist
 
Randy Holmes-Farley's Avatar
 
Join Date: Apr 2001
Location: Arlington, Massachusetts
Posts: 86,233
In any case, all tox issues aside, since the manufacturer claims this Marine P Ceramic Biomedia contains substantial aluminum oxide, and aluminum oxide is known in the scientific literature to release aluminum to fresh water, I think it is reasonable to conclude that elevated aluminum levels may be coming from this Biopure media.

Folks might argue what form it takes, and what harm it may cause (if any), but the potential for it to possibly be the cause of detectable elevated levels in aquarium tests, IMO, is not really much in doubt.


__________________
Randy Holmes-Farley

Current Tank Info: 120 mixed reef
Randy Holmes-Farley is offline   Reply With Quote
Unread 11/03/2014, 03:42 PM   #86
Randy Holmes-Farley
Reef Chemist
 
Randy Holmes-Farley's Avatar
 
Join Date: Apr 2001
Location: Arlington, Massachusetts
Posts: 86,233
Quote:
Originally Posted by shermanator View Post
Couldn't an alternative hypothesis be that it was due to rapid phosphate changes? [I know nothing about Phosguard, but a quick google search indicated SeaChem suggests using small amounts at a time.] I'm not arguing that is the cause, but it's at least a possibility, no?
In a few hours? I don't think that is consistent.


__________________
Randy Holmes-Farley

Current Tank Info: 120 mixed reef
Randy Holmes-Farley is offline   Reply With Quote
Unread 11/03/2014, 03:43 PM   #87
hart24601
Registered Member
 
Join Date: Dec 2012
Posts: 633
That's a bummer. I bought two blocks of it for an expansion...

Well at least the vidarock didn't raise my tank's aluminum.


hart24601 is offline   Reply With Quote
Unread 11/03/2014, 03:48 PM   #88
dartier
Registered Member
 
Join Date: Aug 2012
Location: Brampton, ON, Canada
Posts: 958
Quote:
Originally Posted by Maximus View Post
I wish I understood what you two are talking about!
Let me see if I can put it into layman's terms for the rest of us...

This week on Fe(III) Chef

... now entering Labratory Stadium, the challenger, shermanator facing the reigning master, Randy Holmes-Farley.

And now to reveal this weeks, secret ingredient [Chairman Kaga whips the covering from the table with a flourish] PHOSGUARD!! [gasps: from the audience at the sheer mountain of phosguard!]



Dennis


__________________
560G Miracles tank in process
making a DIY DyMiCo style filter (for 560G)

Current Tank Info: 560G Miracles tank in progress, 80Frag Temporary
dartier is offline   Reply With Quote
Unread 11/03/2014, 03:52 PM   #89
Electrobes
Montipora type guy
 
Electrobes's Avatar
 
Join Date: Dec 2003
Location: Fort Myers, FL
Posts: 2,945


My head won't stop spinning


__________________
Christian

Current Tank Info: 100G Half Cylinder
Electrobes is offline   Reply With Quote
Unread 11/03/2014, 04:17 PM   #90
shermanator
Registered Member
 
Join Date: Feb 2014
Posts: 854
Quote:
Originally Posted by Randy Holmes-Farley View Post
Well, I disagree. Read the linked paper before asserting the aluminum oxide is not soluble.
I skimmed it. Will read it tonight. I didn't see any data that wasn't at pH 4. Is there any?


shermanator is offline   Reply With Quote
Unread 11/03/2014, 04:22 PM   #91
rogergolf66
im an addict lol
 
rogergolf66's Avatar
 
Join Date: Jul 2006
Location: Land o lakes, FLorida
Posts: 12,930
Wow


__________________
Goal levels: salinity 35ppt, temp 78-79, alk 8-9, cal 430-450, mag 1310-1400 po4 .03, no3 1-3

Current Tank Info: System 1... 100 gal Zoa tank I built, 30 gal Ric Yuma shroom tank, 30 gal mix tank my sons,40 gal softie tank, 40 gal nem tank, two 40 gal LPS tank. System 2... 240 gal SPS display attached 100 gal frag SPS only tank.
rogergolf66 is offline   Reply With Quote
Unread 11/03/2014, 05:07 PM   #92
Randy Holmes-Farley
Reef Chemist
 
Randy Holmes-Farley's Avatar
 
Join Date: Apr 2001
Location: Arlington, Massachusetts
Posts: 86,233
Quote:
Originally Posted by shermanator View Post
I skimmed it. Will read it tonight. I didn't see any data that wasn't at pH 4. Is there any?
No, but your argument that it isn't soluble would have applied at pH 4.

The full pH graph is in Pankow, "Aquatic Chemistry Concepts", but for amorphous aluminum hydroxide, not the dehydrated corundum. Still, the shape will be the same, just moved down a bit.

At pH 8.2, it shows a bit higher than 10^-4 M (2.7 ppm). At pH 4 is shows about 800 ppm.

Since corundum is about 31 fold lower at pH 4, it will also be about that same lower at pH 8.2, so about 2.7/30 ~0.1 ppm.

I measured 0.4 ppm.

IMO, that is close enough to suggest that what I saw is soluble aluminum from aluminum oxide.

I'll try to scan and post it.


__________________
Randy Holmes-Farley

Current Tank Info: 120 mixed reef
Randy Holmes-Farley is offline   Reply With Quote
Unread 11/03/2014, 05:37 PM   #93
shermanator
Registered Member
 
Join Date: Feb 2014
Posts: 854
Quote:
Originally Posted by Randy Holmes-Farley View Post
No, but your argument that it isn't soluble would have applied at pH 4.
I think all of my posts said normal reef tank pH. I know strong acid will dissolve alumina.

If you can post that plot, would be great.

We should be able to calculate this via k-sp. I'll work on it after the kids are in bed.


shermanator is offline   Reply With Quote
Unread 11/03/2014, 06:19 PM   #94
Randy Holmes-Farley
Reef Chemist
 
Randy Holmes-Farley's Avatar
 
Join Date: Apr 2001
Location: Arlington, Massachusetts
Posts: 86,233
Here's the curve for aluminum solubility as a function of pH in fresh water.

It is for aluminum hydroxide, so the data for aluminum oxide will be the same curve, but moved straight down becasue it is a more stable crystal form. That said, I don't think we know what crystal forms Phorguard shows on its hydrated surface, so it would likely be between amorphous corundum and amorphous aluminum hydroxide.

I believe it is correct to cross over the data at pH 4 (where we have data for both forms), as I mentioned above, giving solubility for corundum around 0.1 ppm in fresh water at pH 8.2




__________________
Randy Holmes-Farley

Current Tank Info: 120 mixed reef
Randy Holmes-Farley is offline   Reply With Quote
Unread 11/03/2014, 07:16 PM   #95
bigzman
Registered Member
 
Join Date: Dec 2002
Location: New Tampa FL
Posts: 2,807
Randy, any chance you might know if seachems matrix bio media might have the same issue as I have used it in both reef and discus tanks.


__________________
330g SPS - LED/T5 - EShopp S-300 Skimmer - 4 x Jebao PP20- reefkeeper elite

Current Tank Info: 210 gallon mixed reef lps sps
bigzman is offline   Reply With Quote
Unread 11/03/2014, 07:49 PM   #96
shermanator
Registered Member
 
Join Date: Feb 2014
Posts: 854
Okay, I'm back. A couple notes after reading the Peryea paper:

1) All their data is at pH 4, and over a long time scale (15–45 days).

2) Their mechanism for solubilization is a protic solubilization and requires 6 protons per Al2O3 (equation 1) to make 2 Al(III)

3) At pH 4 and 15 days, they measure 9x10^-4 M Al(III) or ~30 ppm Al(III)

4) At pH 8, there are 10^4 fewer (free) protons compared to pH 4.

If you ballpark 3) and 4) above, at pH 8, there isn't going to be anywhere near 0.1 ppm Al(III) in solution.

I'm not sure you can use the aluminum hydroxide curves. It's a very different process. With aluminum hydroxide you are looking at dissolution of ions. With Al2O3 (alumina), there is a chemical reaction that is occurring and requiring protons (or hydroxide). But, this is getting outside my chemistry area of expertise so I might be wrong about the applicability of that curve.

I really couldn't find much on the solubility of alumina. I found some papers saying they got micrograms to dissolve, but that was at 800 degC and high pressure. I'll just say it's not very soluble.

Maybe this is getting too academic? I'm still willing to test for soluble Al(III) as I proposed earlier, but I want you to help design the experiment so that you will accept the results. No point in spending time and money if neither of us will be convinced (or the experiments are not designed in a way to tell us anything informative).



Last edited by shermanator; 11/03/2014 at 08:33 PM.
shermanator is offline   Reply With Quote
Unread 11/03/2014, 07:50 PM   #97
mikeatjac
Registered Member
 
mikeatjac's Avatar
 
Join Date: Aug 2004
Location: Jacksonville, Florida
Posts: 2,433
Quote:
Originally Posted by bigzman View Post
Randy, any chance you might know if seachems matrix bio media might have the same issue as I have used it in both reef and discus tanks.
I would like to know too. I run a 6' tall matrix reactor so I can use very little live rock.


mikeatjac is offline   Reply With Quote
Unread 11/03/2014, 08:44 PM   #98
shermanator
Registered Member
 
Join Date: Feb 2014
Posts: 854
Quote:
Originally Posted by Randy Holmes-Farley View Post
In any case, all tox issues aside, since the manufacturer claims this Marine P Ceramic Biomedia contains substantial aluminum oxide, and aluminum oxide is known in the scientific literature to release aluminum to fresh water, I think it is reasonable to conclude that elevated aluminum levels may be coming from this Biopure media.
Again, I'm not sure extrapolating a protic process at pH 4 (as found in the scientific literature) to a reef tank is appropriate.

Quote:
Folks might argue what form it takes, and what harm it may cause (if any), but the potential for it to possibly be the cause of detectable elevated levels in aquarium tests, IMO, is not really much in doubt.
I agree that adding any alumina-based product could cause atomic Al to show up in an ICP. But given that some forms of Al are toxic and some inert, ICP is clearly a terrible way to look at Al (and many other atoms).

I'm all for science and adding technology to everyday life. But, as evidenced in our debate, I fail to see how ICP (Triton) tells us anything useful about Al levels. It causes panic and concern when no one (including both you and I) knows if the elevated atomic Al is concerning (aluminum hydrates) or inert (Al2O3).


shermanator is offline   Reply With Quote
Unread 11/04/2014, 05:02 AM   #99
Randy Holmes-Farley
Reef Chemist
 
Randy Holmes-Farley's Avatar
 
Join Date: Apr 2001
Location: Arlington, Massachusetts
Posts: 86,233
Quote:
Originally Posted by shermanator View Post

If you ballpark 3) and 4) above, at pH 8, there isn't going to be anywhere near 0.1 ppm Al(III) in solution.

I'm not sure you can use the aluminum hydroxide curves. It's a very different process. With aluminum hydroxide you are looking at dissolution of ions. With Al2O3 (alumina), there is a chemical reaction that is occurring and requiring protons (or hydroxide). But, this is getting outside my chemistry area of expertise so I might be wrong about the applicability of that curve.

I
I guess we will just disagree on this.

But as a final comment, you are confounding thermodynamic data with kinetic comments (the days comment).

Phosguard is designed to be a very high surface area material. I don't know exactly what the paper used, but I expect it was not like Phosguard, and so will dissolve more slowly than Phosguard. I see no reason to not think it reaches equilibrium faster.

You certainly can use the Al(OH)3 curve for thermodynamic purposes. The dehydrated Al(OH)3 forms (as phosguard is) will have a more stable crystal, so has a lower equilibrium solubility at every pH, but the pH effects must be exactly the same since all of the forms in solution are identical.


__________________
Randy Holmes-Farley

Current Tank Info: 120 mixed reef
Randy Holmes-Farley is offline   Reply With Quote
Unread 11/04/2014, 05:06 AM   #100
Randy Holmes-Farley
Reef Chemist
 
Randy Holmes-Farley's Avatar
 
Join Date: Apr 2001
Location: Arlington, Massachusetts
Posts: 86,233
Quote:
Originally Posted by shermanator View Post
I'm still willing to test for soluble Al(III) as I proposed earlier, but I want you to help design the experiment so that you will accept the results. No point in spending time and money if neither of us will be convinced (or the experiments are not designed in a way to tell us anything informative).
Can you explain how the experiment works?

I don't really know much about fluorescence of aluminum, or if different forms that might exist (organic chelated, Al(OH)3, Al(OH)4-, Al(OH)3CO3--, etc. will have different emissions, or all overlap and be countable, and how you distinguish very fine particles from soluble aluminum, or even what that means if they are small aggregates of a few aluminum atoms.


__________________
Randy Holmes-Farley

Current Tank Info: 120 mixed reef
Randy Holmes-Farley is offline   Reply With Quote
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On



All times are GMT -6. The time now is 11:26 AM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2024 Axivo Inc.
Use of this web site is subject to the terms and conditions described in the user agreement.
Reef CentralTM Reef Central, LLC. Copyright ©1999-2022
User Alert System provided by Advanced User Tagging v3.3.0 (Pro) - vBulletin Mods & Addons Copyright © 2024 DragonByte Technologies Ltd.