Kalk Question

[Winschuc]

Hello,

I've read most of the information I can find on Kalk dosing, but still have a question. I'm currently dosing as part of my ATO, but am not mixing Kalk to full saturation (1-.5 tsp/Gal). The reason for this is my demand is extremely low at the moment (only a few LPS).

My question is in regards to the settling of the slurry - since I'm 25-50% of saturation is it an issue if i keep a power-head running on my ATO/mixing container? Most of what i've read about dosing "milky kalk" seems to refer to fully saturated limewater.


As information, the reason why I am asking/doing this is because i have extremely limited space in my apartment and the plug for the power-head is difficult to reach. Just trying to make the process easy.

 

[Randy Holmes-Farley Verified Community Expert]

It is not desirable to stir constantly as that just drives more CO2 into the water, depleting the limewater unless you have very carefully sealed it.

Any solids you have after mixing for an hour or two are probably not calcium hydroxide but rather calcium carbonate that has formed between the CO2 in the air and the limewater. There's no need to want to dose that. Letting it settle out is a better plan as it takes impurities out with it (such as heavy metals and phosphate).

 

[Winschuc]

So, regardless of the level of saturation, the best practice is to let the kalk settle prior to dosing. Thank you!

 

[zemuss]

Also I wouldn't do the inline ATO setup as evaporation can increase thus adding more kalk than you need. Rather use the ATO as is and put the Kalk on a timer.

 

[Randy Holmes-Farley Verified Community Expert]

Also I wouldn't do the inline ATO setup as evaporation can increase thus adding more kalk than you need. Rather use the ATO as is and put the Kalk on a timer.

Limewater on a timer and pump is a fine plan, but I've used it in my ATO for 19 years and it has served me well.

I'm not, however, especially focused on a specific alkalinity level as my creatures do not seem to care that much.

If I had an SPS ULNS tank, I might be more concerned.

 

[Randy Holmes-Farley Verified Community Expert]

So, regardless of the level of saturation, the best practice is to let the kalk settle prior to dosing. Thank you!

Yes, that is correct.

This has more:

What Your Grandmother Never Told You About Lime by Randy Holmes-Farley - Reefkeeping.com

 

[gdemos]

Randy, following up on this... do you have any experience or thoughts on Brightwell's Kalk +2 (from a chemists perspective).
i've gathered mixed opinion on the ability to combine an alkalinity, magnesium, strontium based additive.
would this formula also follow the path of 'saturation limit' of 2 tsp/gal ? And that ratio i imagine is subject to many things right, e.g. mixing solvent (RODI), temp, etc.?

thanks
-Greg

 

[zemuss]

I guess I am just trying to be safe here with the Kalk on a timer. I have had it in-line with an ATO which caused a ALK spike on occasion that the ATO was running longer than normal.

 

[fungia_fiend]

I run a pump (MaxiJet 600 in a brute trashcan) after adding my kalk for 15 minutes or so. That's plenty of time to mix it up.Then I let it settle and don't dose the bottom slurry. If you have a smaller container you could just mix it with a piece of PVC then let it settle.

I use a litermeter to dose my kalk and love it. I just dial in my daily dose, and it splits it to 150 doses per day.

 

[Randy Holmes-Farley Verified Community Expert]

Randy, following up on this... do you have any experience or thoughts on Brightwell's Kalk +2 (from a chemists perspective).
i've gathered mixed opinion on the ability to combine an alkalinity, magnesium, strontium based additive.
would this formula also follow the path of 'saturation limit' of 2 tsp/gal ? And that ratio i imagine is subject to many things right, e.g. mixing solvent (RODI), temp, etc.?

It is a misleading product, and I would never buy or use it.

First, it doesn't have any more magnesium in it than does bulk, cheap, calcium oxide/hydroxide (I've measured it).
Second, that amount is pretty low.
Third, and most important, the magnesium is not soluble in limewater. It just sits there on the bottom and won't get to the tank.

The strontium in it and other bulk lime products will get to the tank, but I'm not convinced that strontium is useful.

So personally, I see no use for this product.

 

[Winschuc]

Is there any benefit to mixing Kalk multiple times? Once the water reaches saturation it stays saturated until there is a change in water volume correct?

Also, how is running. Small pump inside a reservoir different than running. Neilsen reactor? From my reading, please note I'm only going off of reading here, the neilsen keeps Kalk slightly suspended then ATO water is pulled through the slurry. Wouldn't this cause milky kalkwasser?

 

[Randy Holmes-Farley Verified Community Expert]

Right. There is zero benefit to stirring multiple times unless you add more fresh water that needs to have calcium hydroxide dissolved into it. As I mentioned, stirring is detrimental as it drives CO2 into it, depleting the limewater.

A reactor is very carefully sealed against the entry of CO2, and it MUST be frequently stirred as new fresh water is constantly being added.

Reactors are usually designed so that the undissolved solids stay near the bottom of the reactor and the mostly clear limewater passes upwards and out near the top of the reactor, leaving most of the solids behind. Some reactors do not get to saturation, and for many people, that is fine.. Others, if misadjusted, may deliver milky limewater. That is undesirable.

 

[gdemos]

But Wouldn't the milky limewater added to the aquarium system be further dissolved as it mixes in the system?

 

[Randy Holmes-Farley Verified Community Expert]

Yes, and a few people use it who cannot get enough potency from saturated limewater.

But milky limewater carries two risks:

1. Any impurity in the limewater is delivered to the tank, where settled limewater precipitates and removes such things as phosphate and heavy metals such as copper.

2. It is much more likely to cause precipitation of calcium carbonate on the solids, and nearby as they dissolve, causing a locally very high pH and alkalinity.

3. If the particles do not dissolve before landing on an organism, they will be very irritating.

FWIW, most of my precipitation events (where the aquarium turns to milk from precipitation of calcium carbonate everywhere) were cuased by my doser sucking up mud from the bottom of my limewater container and delivering a lime slurry to the tank instead of clear settled limewater.

These have more:

What Your Grandmother Never Told You About Lime by Randy Holmes-Farley - Reefkeeping.com

Chemistry And The Aquarium: Metals In Limewater ? Advanced Aquarist | Aquarist Magazine and Blog

The Degradation of Limewater in Air - Reefkeeping.com

Aquarium Chemistry: Magnesium And Strontium In Limewater ? Advanced Aquarist | Aquarist Magazine and Blog

 

[zemuss]

Randy your above risks # 2 especially is why I stopped using my Kalk Reactor in-line with the ATO. If I go back to this mething I would put the Kalk Reactor on a timer to prevent this from happening.