Kalkwasser question

[rmcgary]

I recently built a Nilsen Reactor (Bill Esposito version, with a few adjustments) for dosing Kalkwasser. It seems to be doing fine; however, being new to all of this and having previously never dosed Kalk I have a question for those of you more experienced.

The line from the reactor to the tank is roughly 3'. The line is standard air hose tubing. I dose the Kalk at a rate of 100 ml per hour 24/7. After 3 days of dosing Kalk I began to notice a white precipitate in the tubing. I cleaned out the tubing and it again appeared in approximately 3 days. I am assuming the white precipitate is a calcium based precipitate, presumably the lime. Does the lime settle out of the water? I make sure the effluent being pumped from the reactor is not cloudly, although it is opalescent. Is this normal? My ca readings are fine, 440 - 460 ppm and my alk runs between 3.2 - 3.8. I'm just curious about the precipitate. Thanks for any comments.

Richard

[bill-e]

I would say that is normal. You might want to make sure your limewater solution is not milky...make sure that when you are mixing the kalk, the milky solution dowsnt rise above the powerhead.

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Bill Esposito
bespo@cereal.mv.com
http//cereal.mv.com/reef
The box said "Use Win 95 or better", I chose better so I run OS/2!

[tdwyatt]

The white precipitate is most likely Calcium Carbonate from atmospheric CO2 or dissolved sources in the aquaria. It will actually aid in building your buffer capacity in a round about way, Somewhere I sent a post about this some months abo (the balencing act in the seesaw of CaC3 and CO2 in the aquaria going through the carbonate/bicarbonate buffer system). The idea of using Calcium oxide to make Kalkwasser is that it doesn't add an unnecessary anion in providing Calcium (as would Calcium Chloride or sulfate, etc) Although adding CaCO3 is not necessarily what we want to do (it DOES precipitate , and it's solubility is VERY low) as the creatures of the tank sink Calcium, the remaining Carbonate anions will push the equilibrium point of the reaction for the formation of CaCO3 backwards (to form more soluible Carbonate and bicarbonate "reactants" ) which will improve the tanks alkalinity (buffer capacity) I'd explain it more, but it is VERY late here, I'm going to bed.

Hope this helps

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Tom <"{{{{>(
(TDWyatt)
Wise men talk because they have something to say; fools, because they have to say something. -Plato

[rmcgary]

Tom

Thanks for the explanation but now I have another question (It seems the more I learn the more questions I have). The Nilsen Reactor is a sealed system. RO water pumps into the system through the use of a peristalic pump and Kalk is pumped out of the top. I have ensured there is no air in the reactor or any air bubles in the line. If the white precipitate is, in fact, CaCO3 (which I do not doubt), from where would the CO2 be coming?

[rmcgary]

[quote]make sure that when you are mixing the kalk, the milky solution dowsnt rise above the powerhead.

Bill

Actually, the milky solution is about 2 inches above the pwerhead. The water colum above the milky solution, however, is translucent. This leaves a water column of approximately 10" of translucent effluent. Hence, I do not believe the undissolved lime is being pumped into the tank. It just seems either the lime is settling out or there is the formation of CaCO3 in the line somehow. I just needed to know if this was normal.

Richard

[horge]

hi rmcgary

There's lots of friendly stuff in tank water that can lock onto the free calcium and form precipitates. It's totally normal for interactions to take place where calcium is freshest, the reactor and the output line, and the precipitate you observe proves that.

Some use precipitation to reduce phosphate levels in their tankwater: the calcium locks phosphate down, and then it's a matter of gathering the precipitate for true removal:

Easiest by piping the effluent, precipitates or no, into the skimmer chamber. The precipitate (whether formed back in the effluent line or newly formed in the skimmer chamber) gets floated up by the foam and winds up in the skimmer collection cup.

Just a thought

horge

[tdwyatt]

the dissolved CO2 in the water column (or PO4) for that matter) is normal in aquarium or seawater, and is the result of metabolic respirations in the tank. These drive the pH swings we see in seawater (although it is more prevalent in aquaria, and we see wider swings in the aquaria than we see in the ocean, unless you're talking about a shallow bay with poor circulation). If you have a refugium, the CO2 produced by the macroalgea when the lights are off will drive the pH down, only to be removed by the use of chlorophylls when the lights are on (both macroalgea and zooxanthellae) as demonstrated by the subsequent rise in pH during the "day". I don't see any reason for alarm unless it is the undissolved lime from the bottom of the container, as stated before, it will actually help improve your alkalinity (if it is CaCO3). Personally, I like the idea of using the skimmer to remove phosphate... Hmmmmmmm......

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Tom <"{{{{>(
(TDWyatt)
Wise men talk because they have something to say; fools, because they have to say something. -Plato