Phosphate E and ICP

[ReefHunter006]

it seems logical that if lanthinum is present in an ICP test, the corresponding phosphate would be present as well from LaPo4? Correct?

My recent results show 36ug/l of lanthanum and .05mg/l of phosphate - 15.09ug/l phosphorus.

I am not sure what amount of lanthanum it takes to bind phosphate, but seems very possible there isn't any available phosphate in my system because it is completely bound and the icp is just registering only LaPO4?

How would you interpret this result from ICP? I hoe there isn't just a large amount of lanthanum floating around.

Hobby test kits show PO4 around .06 at the time the water sample was taken.

 

[ReefHunter006]

Worth noting: it took nearly 750mls over 1.5 months to reduce po4 on hobby test kits from .4 to .08.

Which seems like a lot to me. Tank is 250ish gallons.

 

[ReefHunter006]

One last thing I would add is that before I sent the sample I filter the water with a .22micron syringe filter, so I don’t believe 1 micron filter socks are doing much.

 

[Randy Holmes-Farley]

What icp company?

Phosphate from icp P does not necessarily mean actual orthophosphate.

Lanthanum can and is present as a dissolved ion in normal seawater which also contains phosphate. I am not certain of the equilibrium amount of lanthanum at any given phosphate level.

. Lanthanum phosphate precipitates as particles, and unless they are very small, they will not make it into an icp plasma.

 

[ReefHunter006]

What icp company?

Phosphate from icp P does not necessarily mean actual orthophosphate.

Lanthanum can and is present as a dissolved ion in normal seawater which also contains phosphate. I am not certain of the equilibrium amount of lanthanum at any given phosphate level.

. Lanthanum phosphate precipitates as particles, and unless they are very small, they will not make it into an icp plasma.

Ati icp oes

So the labthanum showing up is likely residual from dosing?

How would you reconcile the phosphorus, the test kits, and how to proceed?

Currently, if I skip a day phosphate rises between .05-.08 ppm if I dont dose 15ml of water phosphate e which the recommended dose is roughly 3-4ml for the increase I referenced so I am on edge about adding so much daily to maintain.

 

[SaltyMcBubble]

it seems logical that if lanthinum is present in an ICP test, the corresponding phosphate would be present as well from LaPo4? Correct?

My recent results show 36ug/l of lanthanum and .05mg/l of phosphate - 15.09ug/l phosphorus.

I am not sure what amount of lanthanum it takes to bind phosphate, but seems very possible there isn't any available phosphate in my system because it is completely bound and the icp is just registering only LaPO4?

How would you interpret this result from ICP? I hoe there isn't just a large amount of lanthanum floating around.

Hobby test kits show PO4 around .06 at the time the water sample was taken.

Your system is not full of unbound lanthanum causing problems. The PO4 level looks good, and 36 µg/L La is well below levels that typically cause acute issues for corals or most fish. Some sensitive fish (especially tangs) can react to free LaCl if it’s not fully reacted/filtered, but you’re not in that danger zone.
To clean it up and keep La from creeping higher:
• Dose more slowly / more diluted, ideally into the skimmer or a fine filter sock (10–25 µm recommended).
• If you’re already doing continuous low-dose, you may be able to back off slightly now that PO4 is stable.
• Re-test in a couple weeks (both ICP + hobby kit) after any adjustments.
You’re in a solid spot overall—PO4 under control without crashing the tank. The detectable La is just feedback that the dosing/filtering balance can be refined a bit. No red flags here.

 

[Randy Holmes-Farley]

Ati icp oes

So the labthanum showing up is likely residual from dosing?

How would you reconcile the phosphorus, the test kits, and how to proceed?

Currently, if I skip a day phosphate rises between .05-.08 ppm if I dont dose 15ml of water phosphate e which the recommended dose is roughly 3-4ml for the increase I referenced so I am on edge about adding so much daily to maintain.

I’m not seeing any difference between home and icp measurement of ohosphate. I’d assume those are correct, the value is fine, and I would not worry about the detected lanthanum, whether it is accurate or not. :)

 

[Randy Holmes-Farley]

Your system is not full of unbound lanthanum causing problems. The PO4 level looks good, and 36 µg/L La is well below levels that typically cause acute issues for corals or most fish. Some sensitive fish (especially tangs) can react to free LaCl if it’s not fully reacted/filtered, but you’re not in that danger zone.
To clean it up and keep La from creeping higher:
• Dose more slowly / more diluted, ideally into the skimmer or a fine filter sock (10–25 µm recommended).
• If you’re already doing continuous low-dose, you may be able to back off slightly now that PO4 is stable.
• Re-test in a couple weeks (both ICP + hobby kit) after any adjustments.
You’re in a solid spot overall—PO4 under control without crashing the tank. The detectable La is just feedback that the dosing/filtering balance can be refined a bit. No red flags here.

While it may be free lanthanum that bothers tangs, it may also be particulate forms. I don’t think this distinction has been demonstrated.

 

[ReefHunter006]

I’m not seeing any difference between home and icp measurement of ohosphate. I’d assume those are correct, the value is fine, and I would not worry about the detected lanthanum, whether it is accurate or not. :)

Thank you.

So you don’t think the PO4 being picked up by the test kit and ICP is bound up PO4 at LaPO4 and I am actually at zero phosphates.

 

[Randy Holmes-Farley]

Thank you.

So you don’t think the PO4 being picked up by the test kit and ICP is bound up PO4 at LaPO4 and I am actually at zero phosphates.

I think that is unlikely. Is the water cloudy?

You can always add more foods or dose phosphate to get phosphate up to 0.1 ppm.

 

[ReefHunter006]

I think that is unlikely. Is the water cloudy?

You can always add more foods or dose phosphate to get phosphate up to 0.1 ppm.

No, everything seems ok. An angry acan but its only a couple weeks old.

Po4 rises no problem. If I skip a dose today it will rise quickly back to above .1 by tomorrow. Thsts why I feel I need to keep dosing but that concerned me.

 

[Randy Holmes-Farley]

I don’t see a reason to be worrying about phosphate too low.