Questions about Lanthanum Dosing

[Aydee]

For carbon dosing (Vodka/Methanol/Sugar/Vinegar) read up VERY thoroughly. I mean very thoroughly. And start super slow. We're talking if you dose daily, it should take about a month to get up the recommended daily dose. Increasing a tiny fraction each time. I dose about 40ml white vinegar daily for my tank. (Less dense carbon source so you need more. Vodka will be something like 4 or 5 ml off top of head for your tank. But look it up and don't rely on my top of head!)

For water change the more your remove, the less Lanth you'll need. I think the best answer will be "Siphon out as much crud as you can and replace that". I tend to do about 15% water changes, but that's the economy of buckets. I use 22L buckets. Fill with 20L of water. This is approx 15% of 130L. Nothing more fancy than that.

Make sure you scrub and sand sift FIRST and then siphon out what you stir up. Gotta remove the crud!

(And just realized! /waves to a Toowoomba native. Got some friends who moved up that way a few months ago. )

Dave

[Nemo777]

Thanks Dave...water change done tried to romove as much yuck as i could. Will start dosing vodka slowly.

[Aydee]

And I'm going to stress importance of testing.
1) If you're stripping phosphate with lanth, and you manage to remove the PO4, Lanth *will* bond to other beneficial chemicals in your system. You need to ensure you stop if/when PO4 hits 0
2) You need to test nitrates and phosphates whilst dosing carbon (vodka). If either PO4 or Nitrates hit 0, then it will not work! You need to either supplement the nitrate/phosphate, or work out something else. (Post here if you encounter this situation).

Things can change quickly. Especially with lanth. Just about overnight!

So, test often!

Dave

[Onsan]

A few things on the chemistry side of lanthanum.
Lanthanum will only bond with anions, elements with a negative charge, as it has an oxidation state of 3+ it will preferentially bond with anions that exhibit a 3- oxidation state, this is why it is so effective in removing PO4 with its 3- charge (along with solubilities). However, it will bond with other anions with different oxidation states, particularly silicates, and it can impede gas exchange on gill surfaces leading to asphyxiation if overdosed.

The handy thing is though, as PO4 is a 3- charge, and La is a 3+ charge, it bonds in a 1:1 ratio, so if you know that concentration of lanthanum and you know the concentration of PO4, you can calculate the demand and dose accordingly. eg: if you have 1mg/L of PO4, you need to dose your tank to 1mg/L of lanthanum to meet the demand.
For example;
Given a solution of 35% Lanthanum Chloride, of which is ~20% La, or 200,000mg/L.
Given a tank of 100L and a PO4 concentration of 1mg/L.

V1 = C2V2/C1
Where;
V1 = amount required to dose (to be determined)
C1 = conc. of original product (200,000mg/L, see above)
C2 = conc. of diluted product (1mg/L to match with PO4 conc)
V2 = vol. of solution to be diluted to. (tank volume)

V1 = 1mg/L * 100L / 200,000mg/L
V1 = 0.0005L, or 0.5mL.

Now there's a few considerations to make, estimates on volumes, other elements potentially bonded, charge neutralisation with colloidal/organic matter, osmotic leaching of PO4 from rock, etc.
But it should give you a sound starting point on the demand that exists for PO4 binding.
My recommendation is, do the math, monitor the results and adjust as required.

[Downu]

Lanth should only be used to get P04 down to about 0.1. Then use GFO. You will run into trouble if you go any further.

Also, keep an eye on N03 levels. If N03 is high & you bring down P04 too much bad algae will happen.

The dosing rates I am reading here are way to high. I recommend 1 mil max per day for a 700 ltr system.

[smidy69]

FYI I have just started dosing Lanth, .26 po4 level, started with 4ml diluted in 1ltr of Rodi and dosing 25ml of that per day po4 increased to .31. Diluted 10ml of lanth in 1ltr Rodi and started dosing 50ml per day of that diluted solution. Will check results in a few days for levels then. Also about to start dosing vinegar for no3 resection as that's sitting close to 100(Salifert). Remarkably tank is doing pretty well with these levels, full mixed reef.

[Nemo777]

After dosing the phosphates have gone down little. I am going to test my saltwater and rodi water today just to make sure they are not the cause.

My nitrates are at 5 i also have cheato in the sump.

I am concerned about crashing the system completely by adding things to the tank.

[Downu]

1 mil of Lanth not diluted straight into the overlfow Make sure you have a filter sock.

[smidy69]

1 mil of Lanth not diluted straight into the overlfow Make sure you have a filter sock.

Im dosing the diluted stuff just so i dont impact too much, do you think this will still do the job ?

[Nemo777]

No change after dosing. Phosphates still at 1.

Maybe the dose is too low??

Going to try a higher dose diluted in 1/2 liter dripped slowly over a couple of hours.

Hopefully that will help.