CO2 Dispensed auto top-off

[reefermadness]

I am contemplating making a device to dispense Kalkwasser/vinegar solution like this:

 

Two highly accurate float switches

One Solenoid Regulator

A five Gallon Stainless Steel Soda Keg (I used them for force-carbonating beer and they are easy to obtain from soda distributors or fast food places that have changed over to boxes)

 

The kalk would be mixed with vinegar, then water in the keg(s), then pressurized (3-4psi) with CO2. The Kalk solution would remain effective indefinitely this way.

 

The switches (two or three for safety) would control the gas that pushes out the solution when needed.

 

Are there float switches that can be attached to the tank (hang -on or otherwise) that would be accurate enough for this? The medical dosing pump is working OK, but with this method I could make up far more (several kegs) solution at one time and change them out in seconds. The gurgling sound of CO2 in the aquarium should be alarm enough to know when is was time to change kegs (everyone who has been to a keg party has heard it)... I need opinions as to whether or not this could work.

[skeletor]

If you're going to the trouble and expense of getting a CO2 system then why not just build a Calcium reactor and be done with it ?

 

This article has some interesting info about how kalk reacts with CO2 in the aquarium:

 

http://www.animalnetwork.com/fish2/aqfm/19...bio/default.asp

 

"Initially, all that would be accomlished is the formation of some solid calcium carbonate in your limewater bucket."

 

so, I'd suspect you would have the same thing going on inside the keg, even if it is just at the surface. this might also mean you don't need to add any vinegar, but the crusties on the inside of the keg are going to be a pain, expecially when the keg gets near empty and spits all that lovely solid calcium carbonate into the tank.

 

how about using a scuba tank instead of CO2 ?

 

I had a similar idea a while back to make a "batch" reactor, but by the time you get all the CO2 stuff you might as well make a real Ca reactor.

 

-skeletor-

[reefermadness]

I don't know about "expense" since I already own a CO2 system that I use for making beer (and the regulator costs 40 bucks and soda kegs about 5 from my local soda distributor). The "trouble" is also minimal in that I live within minutes of the welding supplier that fills my 25 pound tank for a few bucks. That's not what I asked.... I am asking specifically if you are of the opinion that it is or is not possible, given the accuracy of the available float switches.

 

I have had nothing but success with the Kalkwasser method and I am not interested in using a calcium reactor. The Kalk method has been used for decades and is the most economical method of maintaining Ca, hands down. It is the exceptionally low pH (below 7 to maintain dissolution of the media) of the effluent that concerns me about Ca reactors. The article you site is EXACTLY in line with what I am talking about here and seems to have fairly accurate information with regard to the chemistry of the process, though somewhat vague and incomplete, as is your method of quoting the author. The rest of the paragraph you cited reads:

 

"And, it wouldn’t really help your corals unless you kept shooting carbon dioxide into the bucket until the calcium carbonate formed redissolved. Then you would have something like the product of a calcium carbonate/carbon dioxide reactor in the bucket. If you kept it tightly sealed and dispensed it with a dosing pump, then you might be able to make that work, but it sounds like a nuisance to me."

 

Here, the author is referring to the use of CO2, WITHOUT vinegar and forced CO2 like I am suggesting. It will not be a nuisance at all when done this way. Is it difficult to tap a keg?

 

Quote the WHOLE text you are citing after reading my post carefully. I WILL be dosing CO2 into the "bucket", which happens to be an inert, pressurized container that will fully FORCE carbonate the limewater, just as soda and beer are force carbonated. The carbonate material in the bottom of the container that WILL settle will never reach the aquarium, as the rigid tubing inside the vessel will not reach the very bottom and the particles will fall out of suspension within minutes. That's the reasoning for using the vinegar in the initial mixing process (to minimize leftover solids). And the added carbon compounds will aid in feediing the bacteria in the sand bed and rock, keeping that population healthy. I am currently able to maintain low nitrate levels considering the overstocked aquarium I keep. Ca reactors do not add this benefit and have the potential for pH swings, though subtle, all day long while they are running. My pH is stable no matter what time of day I test.

 

I have had success over the past few years dosing kalk, maintaining Ca levels where they need to be without pH shifts. I'm looking for a low-maintenance alternative to filling and mixing every four days. A Ca reactor built properly with clear PVC and acrylic, various valves, the reactor media, and the addition of a pH monitor/controller that should be used alongside it will surely prove more costly than the thirty bucks a year it will cost me to run the Kalk setup. The crusty stuff will fall mainly to the bottom of the keg and is easily dumped out and rinsed/dried. BTW, a scuba tank, which normally contains air will defeat the purpose of sealing the solution and providing it with the CO2 it needs to maintain its effectiveness.

 

It is the size of the "batch" which is of concern here. If the float switch only kicks the reg. on when the water is an inch down in my sump, then the batch could be larger and subsequently less stable than I would like. Drip, drip, drip is very different from dump, dump, dump......That's what I need to know about the switches.

[skeletor]

Originally posted by reefermadness

That's not what I asked....  I am asking specifically if you are of the opinion that it is or is not possible, given the accuracy of the available float switches.

I think float switches will be the least of your worries. I have 2 el-cheapo ones running my top-off and they seem sensitive enough to water level changes (around 1/8" anyway). so yes, it is possible.

I have had nothing but success with the Kalkwasser method and I am not interested in using a calcium reactor.  The Kalk method has been used for decades and is the most economical method of maintaining Ca, hands down.  It is the exceptionally low pH (below 7 to maintain dissolution of the media) of the effluent that concerns me about Ca reactors.

you seem to be contradicting youself here. you don't want to run an "in-line" calcium reactor but you want to build a "batch" calcium reactor.

The article you site is EXACTLY in line with what I am talking about here and seems to have fairly accurate information with regard to the chemistry of the process

right, but you seem to be missing the point. you are starting off by force carbonating the solution with CO2 and then every time you add it to the tank you are adding more CO2 to the continer holding the solution.

Here, the author is referring to the use of CO2, WITHOUT vinegar and forced CO2 like I am suggesting. It will not be a nuisance at all when done this way.

I think it's a great idea, the only thing you seem to be missing is that the CO2 is going to be used for more that just pushing the liquid out of the container and into the tank..

 

Quote the WHOLE text you are citing after reading my post carefully.

I'm so terribly sorry.

 

did you read that next paragraph:

 

"A different, and I think more productive, route is to spike the limewater with a source of organic carbon. As the limewater is gradually dosed into the aquarium, the organic compound we place in the limewater would serve as a food source for bacteria and perhaps other organisms in the aquarium. As they oxidize the added organic compound, carbon dioxide is generated. And presto, we now have some extra carbon dioxide in the system — and that’s exactly what we needed."

 

except when you already have an abundance of CO2.

 

I WILL be dosing CO2 into the "bucket", which happens to be an inert, pressurized container that will fully FORCE carbonate the limewater, just as soda and beer are force carbonated.

ok, this is the point it turns into a batch calcium reactor. I have no idea how a beer keg works or how FORCE carbonation works but it sounds like you're pushing a whole lot of CO2 into the water. What do you expect the pH of this solution is going to be ?

The carbonate material in the bottom of the container that WILL settle will never reach the aquarium, as the rigid tubing inside the vessel will not reach the very bottom and the particles will fall out of suspension within minutes. That's the reasoning for using the vinegar in the initial mixing process (to minimize leftover solids).

I think there is going to be an abundance of CO2 available, I don't think there are going to be any leftover solids.

Ca reactors do not add this benefit and have the potential for pH swings, though subtle, all day long while they are running.  My pH is stable no matter what time of day I test.

you mean your pH never changes ? day or night, lights or no lights. ok, how exactly are you testing pH ?

I have had success over the past few years dosing kalk, maintaining Ca levels where they need to be without pH shifts.

right, but what do you think all this CO2 is going to do the the pH ? What is the pH of your current kalk/vinegar mix ? Are the two going to be the same ? NO, because you've added a bunch of CO2 and lowered the pH.

It is the size of the "batch" which is of concern here.  If the float switch only kicks the reg. on when the water is an inch down in my sump, then the batch could be larger and subsequently less stable than I would like.  Drip, drip, drip is very different from dump, dump, dump......That's what I need to know about the switches.

What about a precision needle valve or metering valve on the CO2 supply line ? then you could turn it way down and get a drip, drip, drip out of the keg.

 

-skeletor-

[reefermadness]

I understand what you are saying about the CO2 and its reaction with the Kalk solution. I'm just not willing to concede that it has exactly the same properties as a Ca reactor:

 

First, I might have overemphasized the description of "forced" carbonation. We are talking about a meager 3-4 psi of pressure, which would take days to weeks to carbonate the solution if I shook the heck out of it (which will not happen). The CO2 is just meant to keep the solution away from air and a loss of potency (and push the liquid into the tank). Massive amounts of CO2 (truly forced into the solution) would defeat the purpose of keeping things economical and more than likely send the solution's pH into a downward spiral, I understand.

Second, there is no doubt in my mind that the solution could absorb some of the CO2 and the vinegar concentration could be easily adjusted to prevent a low pH situation. The object here is to get the solution into the tank and maintain the same potency for the four or five days it would take to dispense.

 

My pH is tested with a Salifert kit most of the time. As a backup, I use a Beckman Phi 3 (lab-grade meter that also tests conductivity that I picked up on ebay). The liquid kit works, but it's tough to match up the colors (color strips suck with varying light conditions). I attribute the lack of fluctuation to the use of a large 24 hour refugium and the Kalk. My pH used to drop a couple tenths at night, and at times can drop a tenth (using the Beckman), but for the most part it doesn't change day to night.

 

I agree with you that this is some sort of hybrid doser/kalk reactor thingie. However, the benefit of the organic carbon, from the leftover acetate ions brought in by the vinegar are not inherent in a traditional Ca reactor. This is something more than a Ca batch reactor for this reason. I can't add vinegar to a Ca reactor. I know my nitrates are next to nonexistent with a huge fish stock, so something there is working (the refugium and the kicked up kalk solution).

 

I just think it would save me a lot of maintenance and money. That's the thought process behind it. I've also got about twenty soda kegs lying around (haven't brewed a batch of beer for a while). Here is another great article that gets a little more into the chemistry: HERE

[Dingo]

Your premise that you can only keep kalc for 4 days is flawed. A covered container will experience only a marginal loss of effectiveness over time. You are better off just dosing your vinegar spiked kalc from a 35 gallon trashcan.

 

See this article:

 

http://reefkeeping.com/issues/2003-05/rhf/...ature/index.htm

[skeletor]

Originally posted by reefermadness

I might have overemphasized the description of "forced" carbonation.  We are talking about a meager 3-4 psi of pressure, which would take days to weeks to carbonate the solution if I shook the heck out of it (which will not happen).

ok, this part of the process I do not fully understand, so I'll have to take your word for it.

 

I think the delivery system will work, float switches, solenoid and a needle valve should give you a precise enough control over the rate at which it's dispensed.

 

How about mixing up a keg full and testing the pH after 1 day and then again after 1 week ?

 

-skeletor-

[reefermadness]

Dingo-

What a great article...I have read the many claims that Kalk loses it's punch after a few days. Many of these stress doing daily overnight drips for this reason (and to avoid pH swings), but I've never actually seen this assumption taken to task.

 

It seemed to me, looking at my log book, that the solution's effectiveness increased (my Ca remained more stable) when I began to use airtight containers for dosing. This could be attributed to a number of other factors, though. I harvested a large crop of halimeda from the 'fuge the week before the change, which could have also caused an increase in Ca production (or lack of consumption, rather). I may have erroneously assumed that the sealed container allowed production to "catch up" to the organic needs of the reef.

 

The author assumes, though, that the higher concentration of dissolved lime in a "spiked" situation, which tends to be as much as a third higher, will react in the same way as straight lime. It seems he needs less Ca than I do. If it loses the same small percentage of dissolved solids and not a higher one, it would certainly render the soda kegs a useless idea. I can measure the conductivity with a freshly made batch (with vinegar) and measure again at the bottom of the trash can (food grade, of course) and report back with the results of this and Ca levels in a month or so to make sure.

 

The more I read about Kalkwasser, the more I think buying a peristaltic dosing pump was a good idea. The cost of dosing, the top-off water solution, the ability to allow impurities to settle out, feeding organic carbon to the sand bed and rock, exporting phosphate more readily, and improving skimmer efficiency make spiked Kalkwasser seem like a more logical choice than a Ca reactor for my needs.

 

Oh well, I think it's time to buy a big trash can, make some beer, and stop thinking too much (it hurts). Thanks so much for the input all.....

[Dingo]

Send me some of that beer...

 

I make my own this time of year.

[reefermadness]

Me, too...I make the lagers for the spring and summer this time of year and the darker porters and stouts in the summer for now. Let me know what you like and I'll send you a few bottles next time I brew that style (I brew thirty gallons at a time, so I won't miss it, much) E-mail me.....

 

Thanks again-

Dustin