Kalkwasser and Downdraft Skimmers

[Anonymous]

Hello all,

I recall reading somewhere that kalkwasser will reduce phosphate levels more effectively if it is added to the air/water interface at the top of a downdraft skimmer tube, rather than to a turbulent area of the tank.

Does anyone have a source for this, or do you use this method currently? Have you noticed a significant effect?

 

[Anonymous]

Matt,

I would ask whether you have any evidence that apatite precipitates in seawater to begin with.

 

[Anonymous]

There will be study released soon showing down draft to be 6x less effective then the traditional counter current air driven skimmers of back in the day. Not that this is the same topic as wehat your asking Matt

 

[Anonymous]

There will be study released soon showing down draft to be 6x less effective then the traditional counter current air driven skimmers of back in the day. Not that this is the same topic as wehat your asking Matt

Rich and I had an interesting discussion to that effect last week. Where the hell were you?

 

[Anonymous]

Also, with the downdraft skimmer off gassing CO2 and the kalk converting CO2 to carbonates/bicarbonates, I think local precipitation of CaCO3 is plausible.

 

[Anonymous]

Matt,

I would ask whether you have any evidence that apatite precipitates in seawater to begin with.

I don't. Is that the only way it could reduce the level of phosphate in the water?

 

[Anonymous]

There will be study released soon showing down draft to be 6x less effective then the traditional counter current air driven skimmers of back in the day. Not that this is the same topic as wehat your asking Matt

Theoretically, or in actual skimmate production? Hook up the reference, brutha.

 

[Anonymous]

Also, with the downdraft skimmer off gassing CO2 and the kalk converting CO2 to carbonates/bicarbonates, I think local precipitation of CaCO3 is plausible.

This is what I was concerned about. Although it wouldn't be doing any major damage to expensive parts in this location, it would kind of defeat the purpose of adding it in the first place.

 

[Anonymous]

I don't. Is that the only way it could reduce the level of phosphate in the water?

Yes.

 

[Anonymous]

I don't. Is that the only way it could reduce the level of phosphate in the water?

Yes.

Many people, including myself, have noted significant drops in phosphate level in their water after beginning a kalkwasser addition regimen. Do you have an idea how this is happening?

 

[Anonymous]

I don't. Is that the only way it could reduce the level of phosphate in the water?

Yes.

Many people, including myself, have noted significant drops in phosphate level in their water after beginning a kalkwasser addition regimen. Do you have an idea how this is happening?

1) Amorphous calcium phosphate precipitation.

2) Indirectly: you're precipitating fresh calcium carbonate surface for phosphate ion groups to adsorb to.

 

[Anonymous]

Oh yeah, what's "significant"? Forgive me for being skeptical.

 

[Anonymous]

Oh yeah, what's "significant"? Forgive me for being skeptical.

I'd have to dig up the exact numbers, but from what I remember our reef was creeping up to to 0.09 ppm before we started adding dry kalk. It dropped pretty quickly, over the course of a couple weeks. It's at 0.02-0.01 ppm now. No other maintenance changes.

 

[Anonymous]

*shrug* sounds good to me. My feeling is that I think you're continuously precipitating fresh CaCO3 by adding dry kalk, and PO4 is adsorbing onto it.

 

[Anonymous]

I don't. Is that the only way it could reduce the level of phosphate in the water?

Yes.

Many people, including myself, have noted significant drops in phosphate level in their water after beginning a kalkwasser addition regimen. Do you have an idea how this is happening?

1) Amorphous calcium phosphate precipitation.

But you're skeptical that this is occurring?

2) Indirectly: you're precipitating fresh calcium carbonate surface for phosphate ion groups to adsorb to.

Would this be more likely to occur inside a skimmer?

 

[Anonymous]

*shrug* sounds good to me. My feeling is that I think you're continuously precipitating fresh CaCO3 by adding dry kalk, and PO4 is adsorbing onto it.

Sounds kind of like what happens with LaCl additions. Do you see a benefit to having this happen inside a skimmer where the result could be skimmed out (rather than sitting at the bottom of the aquarium)?

 

[Anonymous]

1) Amorphous calcium phosphate precipitation.

But you're skeptical that this is occurring?

Not necessarily, but amorphous calcium phosphate can redissolve. The apatite is the mineral form, and I'm not sure whether apatite or hydroxyapatites would readily form and stay around in seawater.

2) Indirectly: you're precipitating fresh calcium carbonate surface for phosphate ion groups to adsorb to.

Would this be more likely to occur inside a skimmer?

Would what? The precipitation of fresh CaCO3? I would think so.

 

[Anonymous]

Sounds kind of like what happens with LaCl additions. Do you see a benefit to having this happen inside a skimmer where the result could be skimmed out (rather than sitting at the bottom of the aquarium)?

You mean the carbonates would get skimmed out? They might not. Why not just get a more efficient skimmer so you get a trickle down net removal of P through fast removal of organic matter?

 

[Anonymous]

Sounds kind of like what happens with LaCl additions. Do you see a benefit to having this happen inside a skimmer where the result could be skimmed out (rather than sitting at the bottom of the aquarium)?

You mean the carbonates would get skimmed out?

Sure, if the particles are small.

They might not. Why not just get a more efficient skimmer so you get a trickle down net removal of P through fast removal of organic matter?

Besides cost and the downtime associated with installing new skimmers, I don't imagine any skimmer out there can remove all the P in a heavily fed (read: visitor friendly) reef tank. Is it worth $50k to drop the P level that much further? We have to make kalkwasser every day anyhow, and adding it to a different place won't cost anything. If it will help reduce P in the tank without sacrificing Ca/Alk, why NOT do it?

 

[Anonymous]

Matt, before you, how were PE mysis being rinsed?