Vanadium pentoxide- need help from the big brains

[csb123]

I’m using the Triton method and based on my test results I need to dose Vanadium weekly.
For the same $32 for Tritons 100ml supplement, I got 250 grams of 99+% pure Vanadium pentoxide.

It is somewhat soluble in R/O water and the color of the solution is a very similar yellow color to the Triton additive.

I googled the solubility vanadium pentoxide and the info I found was way over my head.

Can anyone help figure out what the concentration of a saturated solution of this, at room temperature, is?

Also, I need advice on how to dose it. For example, how many ml to dose to raise X amount per 100 l of tank water.

Thank you so much, in advance!

 

[Randy Holmes-Farley]

I personally wouldn't try to dose based on a "saturated" solution. Do you have a scale?

 

[csb123]

Photos of the solution.

I do have a scale that’s good to 0.1 of a gram.

 

[Randy Holmes-Farley]

If you have a decent scale, I'd dissolve 4 grams in a liter (saturation is about twice that).

Vanadium pentoxide is about 54% vanadium by weight, so that solution will be about 2,200 ppm (mg/L) or 2,200 ug/mL.

1 mL of this added to 100 gallons (378.5 L) will boost vanadium by 2,200 ug/mL * 1 mL / 378.5 L = 5.8 ug/L.

That's a bit high, so if you dilute the stock again (100 mL into 1 L total) then it is 1/10th as much, or 0.6 ug/L final concentration when dosed 1 mL to 100 gallons.

 

[csb123]

Thank you so much Randy! You are a pillar of R2R!

 

[csb123]

I looks like only a fraction of the 4 grams in 1 L of r/o water dissolved.

Should I add an acid to make it more soluble? Would doing that change it’s state?

Or, is there a way to figure out how much vanadium pentoxide is in solution at saturation?

 

[Randy Holmes-Farley]

I’m not sure why it isn’t dissolving. The published solubility is twice that amount.

You might trying mixing more, or adding sodium hydroxide, if you have any.

 

[csb123]

Shaking the bottle boss. Shaking the bottle. I’ll try the sodium hydroxide.

 

[Randy Holmes-Farley]

I'd try about 0.9 grams NaOH in that liter with 4 grams vanadium pentoxide and see what that does.

 

[topjimmy]

Following along. My ATI test suggests dosing molybdenum and vanadium. Though I don't know if it will make a difference. I would certainly rather have a diy recipe than pay for someone else putting it into solution.

 

[Randy Holmes-Farley]

Vanadium is an element that many people show as undetected. In fact, I suspect most people not dosing it, and who do not have metal parts in the water, will show none, and may benefit from dosing.

 

[csb123]

Success! I ended up adding 1.8 grams of sodium hydroxide. 0.9 grams didn’t dissolve it completely.
Now I have vanadium supplement for life for $40. I’ll be giving about 80% of the vanadium pentoxide and sodium hydroxide powder away to my local fellow reefers.

 

[sticksreef]

Hi @Randy Holmes-Farley you said people with undetectable vanadium which is my case, could benefit from dosing it, whats the benefit? Also my icp test says to add 0.20ml one single dose and not on a weekly or monthly basis.

 

[Randy Holmes-Farley]

Success! I ended up adding 1.8 grams of sodium hydroxide. 0.9 grams didn’t dissolve it completely.
Now I have vanadium supplement for life for $40. I’ll be giving about 80% of the vanadium pentoxide and sodium hydroxide powder away to my local fellow reefers.

Great, I'm glad that worked out.

 

[Randy Holmes-Farley]

Hi @Randy Holmes-Farley you said people with undetectable vanadium which is my case, could benefit from dosing it, whats the benefit? Also my icp test says to add 0.20ml one single dose and not on a weekly or monthly basis.

Every organism needs it, and many get it from the water (all do that are not eating foods that will contain it).

Does a fed coral need vanadium in the water too? I'm not sure on that.

Macroalgae and such that do not "eat' definitely need some in the water, but we do not know what levels become a critical limiting factor to growth.

 

[Randy Holmes-Farley]

Only 54% can work or if I found 90% I can use with it ?

Can you link the exact material? That cannot be vanadium pentoxide.

 

[Randy Holmes-Farley]

Vanadium pentoxide can be only 54% just for knowledge ?

It can be 100% vanadium pentoxide (or less, like 90%), which is 56% vanadium by weight. it cannot be more than 56% vanadium by weight and sill be vanadium pentoxide.

 

[Randy Holmes-Farley]

Randy can you help me with DIY dose of sodium molybdate?
Very appreciate for help

Sure.

Do you have a link to a product you want to use?

 

[Randy Holmes-Farley]

As long as you buy the same type of product, it doesn't matter from who. I wanted to see the chemical form, degree of hydration, etc.

Sodium molybdate has a molecular weight of 206 grams per mole.

Molybdenum has a molecular weight of 96 g/mole.

Thus, sodium molybdate is 96/206 x 100 = 46.6% molybdenum by weight

If you dissolve 1 gram (1,000 mg) in 1 L (1000 mL), that has a concentration of 1 mg/mL sodium molybdate or 0.5 mg/mL molybdenum

Natural levels of molybdenum are close to 10 ug/L.

If you want to boost 100 liters of aquarium water by 10 ug/L, you need 100 L x 10 ug/L = 1,000 ug or 1 mg.

Thus, 2 mL of your stock solution (that is 0.5 mg/mL) will add that 1 mg to the 100 liters of aquarium water.

 

[Randy Holmes-Farley]

Typical answers are anhydrous, or the dihydrate.

The above calculation is for the anhydrous material, like in the picture you posted.