Treating rock with lanthanum

[EeyoreIsMySpiritAnimal]

I would like to soak a couple rocks from my existing (mature) system in new sw and test PO4, then add some Lanthanum and see how effectively it reduces the PO4 level.

My questions:
How long should I soak the rocks before testing?
Do I need a lot of circulation?

How long should I let the rocks sit once Lanthanum is added; same question about circulation.

TIA

 

[EeyoreIsMySpiritAnimal]

The reason I'm attempting this is that my PO4 level is off the chart (over 3ppm per Salifert). I am in the process of slowly adding Tropic Marin Elimi-Phos to my tank - into a 1 micron filter sock as I have tangs. My hypothesis is that a lot of phosphate is in the sand and rocks and that treating some of the rock separately might help speed the overall removal from the system.

 

[Randy Holmes-Farley Verified Community Expert]

Many folks have done this. I'd add the lanthanum pretty soon after adding the rock and water. You want the lanthanum keeping the free phosphate in tte water low.

 

[EeyoreIsMySpiritAnimal]

Many folks have done this. I'd add the lanthanum pretty soon after adding the rock and water. You want the lanthanum keeping the free phosphate in tte water low.

To clarify, I'm treating my existing system, not starting a new one. I'd like to measure how much phosphate is already "bound" to the rock and then see if I can reduce this amount before adding the rock back to the tank.

 

[EeyoreIsMySpiritAnimal]

I guess I'm repeating @kenchilada 's recent experiment... I'll re-read that thread :)

 

[Randy Holmes-Farley Verified Community Expert]

OK, if you want to see how high it raises the phosphate in the new salt water, I'd wait at least 3 days with stirring. It equilibrates fairly fast from surfaces exposed directly, but more slowly from down in pores.

 

[EeyoreIsMySpiritAnimal]

OK, if you want to see how high it raises the phosphate in the new salt water, I'd wait at least 3 days with stirring. It equilibrates fairly fast from surfaces exposed directly, but more slowly from down in pores.

Thanks! This is what I was looking for.