When dosing calcium hydroxide, why is it that eventually reefers need to dose other things? I understand that ph raises to high, but couldn't you just use a more powerful skimmer to compensate?
Why does limewater have a maximum?
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dragon99
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Mostly due to the solubility limit of the calcium hydroxide. Since the limewater has an upper limit of potency at some point you will be dosing more limewater than your tank evaporates.
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pH is the only reason there is a limit to how much calcium can be added to a system with calcium hydrixide. pH increases much faster than the calcium increase. To get around this, calcium salts that do not contain hydroxide are used instead, e.g., calcium chloride.
burningmime
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There's a thread on using carbonated water to reduce pH so you can dose more kalk:
www.reef2reef.com
IMO, it feels a little "mad scientist," but seems like it works.
Soda poppin' ... and how to dose infinite Kalk
Ok, how I arrived at this crazy simple stupid idea was kinda like this: It started a long time ago when wet dry filters were still dominant and only the cool kids built Berlins. I had gotten back into the hobby after being in the Philippines and I was absolutetly enamored with live coral, I...
www.reef2reef.com
Randy Holmes-Farley
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There's a thread on using carbonated water to reduce pH so you can dose more kalk:
IMO, it feels a little "mad scientist," but seems like it works.Soda poppin' ... and how to dose infinite Kalk
Ok, how I arrived at this crazy simple stupid idea was kinda like this: It started a long time ago when wet dry filters were still dominant and only the cool kids built Berlins. I had gotten back into the hobby after being in the Philippines and I was absolutetly enamored with live coral, I...
IMO, that is not a useful thread.
Randy Holmes-Farley
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Some folks do use a slurry of calcium hydroxide in water.
My concerns are that the local high pH as it dissolves may lead to calcium carbonate precipitation, possibly even coating the particles and preventing further dissolution, and the potential for very high pH particulates to land on organisms before they fully dissolve.
blasterman
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Not entirely true. Calcium Hydroxide doesn't care if it's pre dissolved in water or not. The reaction is the same.
When I add calcium hydroxide in low utilization tanks in place of alk/calcium I pull some tank water in a juice jar, mix in the dry calcium hydroxide, shake it, and dump it back it in the tank. There is a temporary cloudiness but it clears fast. If you have a kalk stirrer in a top off it's the *exact* same thing.
You can also use a lot more kalk in holding solution for top off as long as you use a stirrer. Your limitation here is going to be limited to how much kalk your tank can absorb based on size / C02 levels before the precipitation starts forming on pumps. At that point you know you are using too much.
You do not want to just dump dry calcium hydroxide straight in a tank because clumps may drop on corals and it will burn them. However, mixing it dry first like I do works just as well.
If you use kalk strictly for top off and adjust calcium and alk via other means then you likely don't care. you are just using the kalk as a pH boost.
OP
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So is it bad to add dry mix directly to the tank chemstry wise?
If it precipitates to calcium carbonate, wouldn't that be okay just not getting as potent a dose sort of?
If it precipitates to calcium carbonate, wouldn't that be okay just not getting as potent a dose sort of?
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Yes. That main concern aside from wasting it is the possible irritation of organisms from undissolved particulates.
But folks do use slurries. At one point, IIRC, Anthony Calfo used it.
OP
OP
Thanks that clarifies it. Any problem dosing directly into a beckett skimmer? Im thinking it would mix it well there. Or maybe down the overflow.
Randy Holmes-Farley
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The local high pH may lead to precipitation on the inside of the skimmer.
Might be easier to dose sodium hydroxide and calcium chloride, without concern about particulates.
OP
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Why did you recommend sodium hydroxide instead of sodium bicarbonate two part? Ph boost? Oh is it because they are added separately so there is less concern about calcium carbonate precipitation?
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Yes, pH boost.
IMO, it is a better plan than dosing particulate Ca(OH)2, but not better than dissolved Ca(OH)2, assuming the dissolved material meets your needs.
