LaCl Dosing Reactor (No Socks!)

[Daddy-o]

I like it, but seems overly complicated. I just dose into my sump.

 

[vanpire]

The precipitate is LaPO4.

This means you are changing your chloride level in your aquarium and will need to water change it back to balance. Just FYI.

That is an excellent point. I guess the changes in chloride levels are low enough that my regular water changes should make up for it.

 

[Daddy-o]

That is an excellent point. I guess the changes in chloride levels are low enough that my regular water changes should make up for it.

Enlighten me, what is a chloride level?

 

[Dennis Cartier]

The precipitate is LaPO4.

This means you are changing your chloride level in your aquarium and will need to water change it back to balance. Just FYI.

Oops, yes I should have specified LaPO4 as the precipitate. As for altering the chloride level, I agree that this will be a side effect, I am just not sure how significant it will be? We are typically dealing with fractions of 1 ppm for phosphate and the alteration to the chloride level will be (I expect) equally small. I will have to put this question to Randy and see if it is worth worrying about or ends up being a rounding error.

Dennis

 

[vanpire]

Enlighten me, what is a chloride level?

I am no chemist by any means but we started with lanthanum chloride which changed to lanthanum phosphate, leaving chloride ions in the water. These chloride ions might bond to something else but I don’t know. I don’t have the full chemical reactions.

 

[HuduVudu]

Oops, yes I should have specified LaPO4 as the precipitate. As for altering the chloride level, I agree that this will be a side effect, I am just not sure how significant it will be? We are typically dealing with fractions of 1 ppm for phosphate and the alteration to the chloride level will be (I expect) equally small. I will have to put this question to Randy and see if it is worth worrying about or ends up being a rounding error.

Dennis

Depends on how much for how long. Easily remedied with regular decent sized water changes.

 

[HuduVudu]

I am no chemist by any means but we started with lanthanum chloride which changed to lanthanum phosphate, leaving chloride ions in the water. These chloride ions might bond to something else but I don’t know. I don’t have the full chemical reactions.

They don't. Just remember the largest pools of ions in salt water are sodium and chloride. That is why they are chosen when dosing because they are so large it is harder to move them. Just be warned if they do move by signifcants amount they are not fun to get back in line.

 

[Dennis Cartier]

Enlighten me, what is a chloride level?

One of the elements in seawater that contribute to its salinity.

I googled, seawater contains 19,000mg/L of chloride at 35 ppt, so adding the amounts of chloride that we are talking about looks pretty small. Again let's get an expert to weigh in. @Randy Holmes-Farley ?

Dennis

 

[John08007]

1 thing, is the brass valve in contact with salt water? I believe you can leach copper into the water

 

[HuduVudu]

LaCL3 -> LaPO4 + 3Cl (?) ... been a while since I balanced an equation, but my guess is that you are going to add 3x CL to PO4. Randy should be able to clarify this.

EDIT: PO4 is minus three so the equation will be LaCL3 -> LaPO4 + Cl This makes it a one to one drop.

 

[Dennis Cartier]

1 thing, is the brass valve in contact with salt water? I believe you can leach copper into the water

The brass gate valve and elbow are in the water feed line from the house water used for the back flushing. No saltwater/ tank water should ever contact those.

Dennis

 

[Dennis Cartier]

I like it, but seems overly complicated. I just dose into my sump.

I am curious, when you dose into your sump, do you collect the precipate? If you don't, have you noticed any negative side effects? Any problems with tangs?

Dennis

 

[Daddy-o]

I am curious, when you dose into your sump, do you collect the precipate? If you don't, have you noticed any negative side effects? Any problems with tangs?

Dennis

I have been dosing LC everyday for the last 18 days. My average daily dose is enough to remove .1ppm phosphate in 200g. My phosphate was .23 when I slowly started dosing. I havea ton of rock that are leaching. I actually dose into a CPR overflow box that is draining into the sump. I dont collect the precipitate into a sock. There are 2 skimmers in the sump and I have not really noticed any difference in the skim. I have not noticed any cloudiness and all livestock appears to be thriving. I do have 2 yellow tangs. If the consensus is that I need to be running a sock, I will. Is there a concern that the LC will stick to pumps and such? Also as I understand, LC is great when phosphate is high but is less effective when phosphate is lower?
Cheers! Mark

 

[Dennis Cartier]

I have been dosing LC everyday for the last 18 days. My average daily dose is enough to remove .1ppm phosphate in 200g. My phosphate was .23 when I slowly started dosing. I havea ton of rock that are leaching. I actually dose into a CPR overflow box that is draining into the sump. I dont collect the precipitate into a sock. There are 2 skimmers in the sump and I have not really noticed any difference in the skim. I have not noticed any cloudiness and all livestock appears to be thriving. I do have 2 yellow tangs. If the consensus is that I need to be running a sock, I will. Is there a concern that the LC will stick to pumps and such? Also as I understand, LC is great when phosphate is high but is less effective when phosphate is lower?
Cheers! Mark

Your application is similar to mine. I also target a drop of 0.1 ppm for each operation of my reactor. The issue with tangs is that there have been cases where LaCl usage without removing the precipitate has caused breathing issues and in some cases death. It is unclear as to what the correlation of the dosing circumstances are (rate/amount/location) to the issues with tangs.

The precipitate can release the bound PO4, but only at very low PH from what I have read. The PH levels where this occurs though are similar to the levels used in a CaRx, so if your tank comes even close to that, the bound phosphate is the least of your concerns

Concerning pumps, people have had LaCl cause a build up inside of equipment, like skimmers, where they have dosed in close proximity. In these cases, it appeared that the LaCl was being dosed directly into the equipment in question.

As to how effective LaCl is at low levels of phosphate. My understanding is that the Lanthanum is going to become bound with Phosphate very quickly, but if no phosphate, or not enough, is available, then it will bind with another element like carbonate. So if your dosing rate exceeds the amount of phosphate that is going to be present within the area that the reaction is occurring, then you will get a drop in your alkalinity as a sign that too little phosphate is present for the Lanthanum to bind to. For this reason, in my reactor I dose the LaCl very slowly using a 2 RPM Masterflex pump and with the dose amount diluted in 5L of RODI. It takes about 2 days to dose all 5L through the reactor. I also monitor my alkalinity level using my Alkatronic looking for a unexpected drop after a dosing run. I have only ever detected an effect on my alkalinity once, and used that as a gauge for how much LaCl was too much to be dosed at once.

Dennis

 

[Daddy-o]

I do dose slowly. I mix the LC with 16 ounces of RO and drip for 8-10 hours. There is constantly good fresh aquarium water under the drip. I was concerned about dosing into my skimmer as I didnt think the foam that I was dosing into had a fast enough turnover of reef water. My concern is that while I have been testing and dosing every day, I have no real way to determine if the measured phosphate is free or bound to the LC. I did have one issue with a skimmer pump. The wife popped a breaker and the skimmer pump didnt start back up - on but not spinning. Dont know if the LC was to blame.
Cheers! Mark

Here is my high tech doser:

 

[Daddy-o]

The one question that has been digging at me is: If I stop dosing LC for a while and fire up the reactor with GFO or Phosguard, will the Lantanum Phosphate that is probably in my reef bond to the media in the same way free phosphate would?

 

[HuduVudu]

The one question that has been digging at me is: If I stop dosing LC for a while and fire up the reactor with GFO or Phosguard, will the Lantanum Phosphate that is probably in my reef bond to the media in the same way free phosphate would?

It is a precipitate so it will be floating around your tank if you stir it up. Moleculare weight of Lanthium Phosphate is 236.901 g/mol vs. Calcium Carbonate 100.0869 g/mol. So it is slightly heavier than your sand of a similar particle size but because the precipitate is fine it can easily be stirred up. I am not sure if the Lanthium will interact with the free calcium once it is bond with phosphate, but I don't think it will I think it will work similarly to Calcium Phosphate and stay bond in your substrate.

 

[Daddy-o]

It is a precipitate so it will be floating around your tank if you stir it up. Moleculare weight of Lanthium Phosphate is 236.901 g/mol vs. Calcium Carbonate 100.0869 g/mol. So it is slightly heavier than your sand of a similar particle size but because the precipitate is fine it can easily be stirred up. I am not sure if the Lanthium will interact with the free calcium once it is bond with phosphate, but I don't think it will I think it will work similarly to Calcium Phosphate and stay bond in your substrate.

But will the lanthanum phosphate bond in the gfo reactor?

 

[HuduVudu]

But will the lanthanum phosphate bond in the gfo reactor?

I don't think so. I think once it is bound into the lanthium there it will stay until you export it out. Unless of course there is an area of low PH that could re-release it. That wouldn't necessarily be good because now you have lanthium in your tank. Maybe to bind to more phosphate or maybe to bind to carbonate, depending on the conditions.

 

[Daddy-o]

I don't think so. I think once it is bound into the lanthium there it will stay until you export it out. Unless of course there is an area of low PH that could re-release it. That wouldn't necessarily be good because now you have lanthium in your tank. Maybe to bind to more phosphate or maybe to bind to carbonate, depending on the conditions.

Thank you!