got my phosphate under 0.1, now seeing MORE algae...

[BilboB]

I've been adding vodka every night for the last month or so, and my phosphate level has dropped from 0.8 ppm to 0.08 ppm. Nitrates went from 30 ppm to 16 ppm. However, now I'm seeing green algae growing on the sand - I thought lowering phosphates would decrease, not increase nuisance algae?

 

[Randy Holmes-Farley Verified Community Expert]

Trying to deter algae by lowering nutrients often fails because to get it low enough to deter algae, it may also be limiting corals.

A clean up crew is usually a better bet.

 

[Fish Fan]

Be glad it's green

Some sand sifting critters like Nassarius snails, pistol shrimp, or a Conch can help.

 

[BilboB]

Be glad it's green

Some sand sifting critters like Nassarius snails, pistol shrimp, or a Conch can help.

OK, I'll get some more.

 

[BilboB]

Trying to deter algae by lowering nutrients often fails because to get it low enough to deter algae, it may also be limiting corals.

A clean up crew is usually a better bet.

Maybe I should stop dosing vodka. I never had much nuisance algae in the tank before, but I kept reading that phosphates should be less than 0.1 ppm for optimal coral growth.

 

[Fish Fan]

Maybe I should stop dosing vodka. I never had much nuisance algae in the tank before, but I kept reading that phosphates should be less than 0.1 ppm for optimal coral growth.

Dosing vodka has a greater impact on reducing nitrate, and not as large of an effect on phosphate

 

[Subsea]

Dosing vodka has a greater impact on reducing nitrate, and not as large of an effect on phosphate

Curious about that. Considering that carbon dosing grows bacteria, what is the majority of skimmate biomass?
With that said, I assumed N:P ratio of bacteria was close to 16:1.

 

[EnterName]

Dosing vodka has a greater impact on reducing nitrate, and not as large of an effect on phosphate

Curious about that. Considering that carbon dosing grows bacteria, what is the majority of skimmate biomass?
With that said, I assumed N:P ratio of bacteria was close to 16:1.

I have gone through it just for fun:

NO₃: 62.004g/mol
PO₄: 94.97g/mol

So if we assume the Redfield ratio:

16mol • 62.004g/mol = 992.064g
1mol • 94.97g/mol = 94.97g

In readable terms for hobbyists: You would theoretically get rid of 10 times more nitrate than phosphate. However, this doesn't take into account the buffering capacity of the calcium carbonate in your tank so the visible effect will be less pronounced.

There also is the phenomenon of "luxury uptake" where organisms store more phosphate than they actually can immediately utilize. So if you had enough phosphate available those organisms might still use up their own supplies before actually removing phosphate from the water column.

Obviously this is all just theory, nothing tested or validated but maybe there are scientific research papers how carbon spikes change N:P ratios.

 

[Fish Fan]

Curious about that. Considering that carbon dosing grows bacteria, what is the majority of skimmate biomass?
With that said, I assumed N:P ratio of bacteria was close to 16:1.

Wouldn't that 16:1 ratio account for a greater decrease of nitrate and less impact on phosphate? This was my experience with carbon dosing, though phosphate can be tricky because of how it interacts with rock and sand, as EnterName mentions above.

 

[Subsea]

I have gone through it just for fun:

NO₃: 62.004g/mol
PO₄: 94.97g/mol

So if we assume the Redfield ratio:

16mol • 62.004g/mol = 992.064g
1mol • 94.97g/mol = 94.97g

In readable terms for hobbyists: You would theoretically get rid of 10 times more nitrate than phosphate. However, this doesn't take into account the buffering capacity of the calcium carbonate in your tank so the visible effect will be less pronounced.

There also is the phenomenon of "luxury uptake" where organisms store more phosphate than they actually can immediately utilize. So if you had enough phosphate available those organisms might still use up their own supplies before actually removing phosphate from the water column.

Obviously this is all just theory, nothing tested or validated but maybe there are scientific research papers how carbon spikes change N:P ratios.

I am familiar with luxury uptake & storage of iron. I did’t know that happened with phosphate.

 

[Randy Holmes-Farley Verified Community Expert]

Maybe I should stop dosing vodka. I never had much nuisance algae in the tank before, but I kept reading that phosphates should be less than 0.1 ppm for optimal coral growth.

Optimal coral growth and perfectly fine coral growth may be entirely different requirements. Stressing about getting optimal is not worth it unless absolute fastest growth is a critical goal. Some great tanks have 1 ppm phosphate.

 

[EnterName]

I have gone through it just for fun:

NO₃: 62.004g/mol
PO₄: 94.97g/mol

So if we assume the Redfield ratio:

16mol • 62.004g/mol = 992.064g
1mol • 94.97g/mol = 94.97g

In readable terms for hobbyists: You would theoretically get rid of 10 times more nitrate than phosphate. However, this doesn't take into account the buffering capacity of the calcium carbonate in your tank so the visible effect will be less pronounced.

There also is the phenomenon of "luxury uptake" where organisms store more phosphate than they actually can immediately utilize. So if you had enough phosphate available those organisms might still use up their own supplies before actually removing phosphate from the water column.

Obviously this is all just theory, nothing tested or validated but maybe there are scientific research papers how carbon spikes change N:P ratios.

I am familiar with luxury uptake & storage of iron. I did’t know that happened with phosphate.

I figured you were familiar, as I saw many of your quite educated responses here on R2R, but wanted to draw the full picture if I already take the time to write a whole thesis .

I got to reference it in a different thread so it already was worth the effort