phosphate question

[EvilMel]

Is there a reason that I can't just throw a bag of phosphate absorbing media into the back of the RSM?

I'm assuming you would use a phosphate reactor because you'd get a better mixing of the media with the water. More mixing = more contact time with the media. Apparently particle size with the different types of media isn't the biggest concern when it comes to surface area contact of the water with the iron. It seems that the porosity of the media is as important, if not more important. If the media is super porous then the contact with iron will be better than if the media is just fine and not porous.

I'm pretty curious about it.

Let's say that I make the media in the bag sit just under my overflow so that all the water flushes across it. Wouldn't it do pretty well?

I'm researching the GFO since a customer came into the store and neither me nor anyone else could explain to me (molecularly speaking) how the iron bound phosphate molecules.

I felt like a nin-com-poop (one of many, many times I've felt that way lately, I'm sorry to say).

 

[macclellan]

In nanos, lots of people use chemi-pure elite (for phosphates) and seachem's purigen (for DOC and to increase redox) in bags just as you're describing.

Personally, I use carbon and purigen. They are in Seachem's "The Bag" ($6 but the only one I'll ever need) just after filter floss under my overflow.

 

[EvilMel]

Great info!

Thanks a ton.

One question though...do you regenerate your purigen?

Also, I was asking about this for just general information...not necessarily because I was thinking of the RSM.

edit: Information copied off another forum-

Chemi-Pure is basically Granular Activated Carbon (GAC) mixed with Ion Exchange Resins (IER). The IER's will work awesome for a freshwater tank and barely do anything in SW. The Chemi-Pure Elite basically adds Iron-Oxide to remove phosphates so in the end, you have GAC, a phosphate remover, and an IER that doesn't really function in SW.

You are better off with a quality GAC like Black Diamond or Matrix and a resin that actually works in saltwater too like Purigen. If you need phosphate removal, there are many quality ones as well. I'm not saying there's anything wrong with Chemi-pure......I'm just saying it's quite expensive for what you get in a salt

 

[macclellan]

<a href=showthread.php?s=&postid=15262528#post15262528 target=_blank>Originally posted</a> by EvilMel
One question though...do you regenerate your purigen?

Yes.

I can't speak to Chemi-Pure or the accuracy of that quoted info; I've never used it, but know that a lot of people do on nano-reef.com. Might just be group think.

 

[GPhiAce]

I don't have any solid information of why or if this works, but...... I have been running Carbon and phosphagard in my media reactor that I got at the swap. before I began doing this, I posted a thread in the lighting and equipment thread and no-one could come up with a good reason why not to. A few people posted that they have been doing this fro years with Carbon and GFO. I just seperate them with a filter disk. I just assume that the pixy dusk on them worksto remove the evil spirits in the tank. I only think in depth about molecular and cellular things while at school. The rest of the time, I am on mental vacation as I am sure it shows.

 

[goreefer]

I use a bag with about a tablespoon of GFO in my system to keep the phosphate in check. It just kinda floats in the sump. I would need to refresh my brain by again reading Randy Holmes-Farley's articles to get back to the chemistry involved to give you the specifics, that's what happens when you get old, you just know that you are supposed to do it, but can't remember why...
What were we talking about?
Oh look, there goes a chicken!

 

[Pandarian]

Re: phosphate question

<a href=showthread.php?s=&postid=15262067#post15262067 target=_blank>Originally posted</a> by EvilMel
Apparently particle size with the different types of media isn't the biggest concern when it comes to surface area contact of the water with the iron. It seems that the porosity of the media is as important, if not more important. If the media is super porous then the contact with iron will be better than if the media is just fine and not porous.

From how I understand it (through my countless hours of pharmaceutics classes ), I would completely agree. It is important to distinguish that GACs and GFOs bind by adsorption and not absorption. So the amt of free phosphates that can bind is increased with increasing surface area, whether it be through decreasing particle size or through increasing porosity.

The problem that comes is, it is more difficult to measure porosity than particle size. Not only that, different manufacturers/types of GFO will result in differences in porosity.

Also, if I remember correctly, the values of measurable internal surface areas of GFO are lower than that of other media, like GACs. How big of a difference would that make?

But, imo, I think these differences are not really that important. My opinion is that I would rather get some media that is decent, and not necessarily the best, but is much cheaper. That way you can replace it more often without the need of worrying if the media has been exhausted.

<a href=showthread.php?s=&postid=15262067#post15262067 target=_blank>Originally posted</a> by EvilMel

Let's say that I make the media in the bag sit just under my overflow so that all the water flushes across it. Wouldn't it do pretty well?

I've done both a media bag and reactor in the past. And I found that when in the bag, the GFO tends to cake faster. But I think I had the media in the bag for a month at a time. I doubt that it would cake if you replaced the media more often. Say every 1-2 weeks?

<a href=showthread.php?s=&postid=15262067#post15262067 target=_blank>Originally posted</a> by EvilMel
I'm researching the GFO since a customer came into the store and neither me nor anyone else could explain to me (molecularly speaking) how the iron bound phosphate molecules.

I believe Ferric oxide is Fe2O3 and phosphate in an aqueous form would be either HPO4-- or H2PO4-. So assuming that the negative oxygens bound to the phosphate would be slightly more electronegative then then the oxygens of ferric oxide, then it would have a higher affinity for the Fe+++, and will displace them. More than likely, that probably won't happen. There is probably an intermediate of ferric oxide because its in water. Like maybe an hydroxide with an -OH hydroxyl group. That would be much easier to displace. But I'm probably completely wrong though.

 

[planejane]

Mel...I've been using Chemipure Elite and Purigen in my RSM since I set it up. Now, remember I'm a newbee, and don't have experience with anything else. I started using it after reading other's expreiences on a nano web site. It seems to work well, as I have undetectable phosphate and nitrate, as well as NH4 and No2 levels ( Salifert tests). No algae problems , yet, please God of the reefs!
I put in a StevieT media rack under the intake chamber. Usually change out the Chemipure every 3 months and regenerate the Purigen at 2 months.

 

[macclellan]

<a href=showthread.php?s=&postid=15262972#post15262972 target=_blank>Originally posted</a> by macclellan
I've never used it, but know that a lot of people do on reefcentral.com.

^^ That makes no sense.
I said n-a-n-o-r-e-e-f.com forgetting about the thought police and the fact that the answer to everything reef-related is on reefcentral and only on reefcental. Forgive me for thinking otherwise.

 

[planejane]

Fifty lashes with a wet noodle for that Joel!

 

[ct_vol]

Re: Re: phosphate question

Re: Re: phosphate question

<a href=showthread.php?s=&postid=15263639#post15263639 target=_blank>Originally posted</a> by Pandarian
I've done both a media bag and reactor in the past. And I found that when in the bag, the GFO tends to cake faster. But I think I had the media in the bag for a month at a time. I doubt that it would cake if you replaced the media more often. Say every 1-2 weeks?

+1 on caking... Once that happens, especially within the reactor it can be a mess... The water will stagnate within the reactor and then you're doing more harm than good IMO... Just make sure you change it out and don't leave it...

 

[jdieck]

These two articles can tell you a lot more including how it works:
http://reefkeeping.com/issues/2004-11/rhf/index.php
http://reefkeeping.com/issues/2006-09/rhf/index.php#17