Phophate export using a diatom filter and lanthanum.

[reefkeeper2]

There have been several threads here on RC dealing with the use of lanthanum chloride for phosphate removal. Many people drip lanthanum chloride into a skimmer or 5 to 10 micron filter socks to trap the resulting precipitate before it can get back into their display tank. I used this method too for a while but was dissapointed in that I could not get phosphate levels down to a low enough level that I wanted (<0.02ppm). I believe this is because even with the use of the filter socks, some precipitate was getting back into the water . Randy Holmes Farley suggested that even if you can't see a cloudy precipitate, it could still be present which is probably not desireable for your reef.
I have a vortex diatom filter. I use it anywhere from once a month to once a week depending on what I'm doing in the tank. When charged with diatomaceous earth and norit powdered carbon it's unbeatable for polishing the water or removing organic and chemical contaminants. The powdered carbon is the same stuff they flush down peoples stomachs in the Emergency Room when they have OD'd on something and they want to absorb it. This past week I got the idea of using the diatom filter and lanthanum as a way to filter out phosphates. I inject the intake with a diluted solution of lanthanum chloride at about the rate of 2ml per hour. The results have been the best I've seen. Phosphates went from 0.04 to 0.0 (500gal water volume) with a single treatment. Best of all there are no worries of any precipitate or residual lanthanum getting back into the tank. By the time it was finished, the output from the filter was almost nil, being totally clogged with the precipitate.
This is sooo much easier than filter socks.
There are probably not thay many people out there using a diatom filter, but this worked so well I figured I'd share the info with my fellow reefers.

 

[HighlandReefer]

Using the diatom filter is similar to the way the large municipal aquariums use the lanthanum chloride. I had discussed this with Randy, and he felt that the use of a good quality filter is better than filter socks.

For large systems, I can see the justification of using lanthanum chloride, but for most hobbyists, I would stick with GFO.

 

[tmz]

While the diatom filter is probably very effective in filtering the precipitated phoshate particles and your approach sounds quite sound, why do you believe it filters the lanthanum? It has been my understanding that lanthanum buildup was a consequence of lanthanum chloride dosing even when very extensive filtration was used.

 

[coralnut99]

Thanks for sharing your results. Just wondering how your livestock reacted to the drop in phosphates, and what your testing method is?

 

[coralnut99]

Where did you acquire the carbon powder, and did you simply mix it with the diatom powder used in the Vortex?

 

[reefkeeper2]

While the diatom filter is probably very effective in filtering the precipitated phoshate particles and your approach sounds quite sound, why do you believe it filters the lanthanum?

I believe any excess lanthanum that has not bound phosphate and precipitated out is removed by the carbon. I am pretty certain of this because previously my clams had a negative reaction whenever I dosed lanthanum using the filter socks. They would close up or look like they were being irritated for a few days. Now there is no reaction from them at all. The powdered carbon is extremely effective.

Just wondering how your livestock reacted to the drop in phosphates, and what your testing method is?

I have two methods for measuring phosphates. I have a milwakee phosphate meter and a Merke test kit. There have been no reactions at all that I can see with the livestock.

Where did you acquire the carbon powder, and did you simply mix it with the diatom powder used in the Vortex?

The carbon is made by vortex and goes by the name super-char. It can be bought at That Pet Place. It is also known as norit powdered carbon. I place about 2 cups of diatom powder in the jar of the filter and then shake what must be about 4 or 5 tablespoons of superchar in as well. It all mixes together in the filter and coats the filter bag when you prime the filter with tank water.

 

[coralnut99]

Thanks!

 

[tmz]

I use lanthanum as one method along with others to tweak phosphate down.

The lanthanum chloride is a catalyst, as such it is not absorbed by the flocculating inorganic phosphate or joined to it.

The lanthanum as a non organic metal will have little if any affinity for absorbtion by granulated activated carbon.

So in brief, while the phosphate flocculants can be removed by fine mechanical filtration , I believe the lanthanum stays in the tank . This may or may not be of significant consequence since the long term buildup of lanthanum in a reef tank is unknown. Nonetheless it is a factor in selecting an inorganic phosphate export method.

 

[reefkeeper2]

I wonder if there is a way to find out for sure. I guess what is needed is a lanthanum test kit. A good question for the chemistry forum. Here is a pic of the vortex filter. Notice you really can't see the filter pleat because it is covered with the diatom and carbon mix which is turned black by the carbon.

 

[reefkeeper2]

This is what boomer said on the chem forum.

<a href=showthread.php?s=&postid=15424912#post15424912 target=_blank>Originally posted</a> by Boomer

 

[slow_leak]

I have Norit available in pallets of 50 lb bags at work. Once used is called Norit and one is called Darco. I assume Norit is same but am not certain.