Kalk stirrer loses potency. Potential enhancements?

[Crashjack]

After adding new kalk, my kalk stirrer overdoses alk/Ca but then after a maybe a week, it levels off and then my tank’s alk/Ca starts to drop until I replace or add kalk, which occurs every 2 weeks. I have a 3-way valve which allows me to switch to straight RO, and I often go from running kalk 12 hours per day with Ca/alk rising, to running kalk 24 hours/day with Ca/alk falling. Even with the stirrer stirring 24/7, the kalk loses potency. My understanding is that the RO entering the stirrer should saturate with kalk as long as there is enough kalk in the stirrer (for instance, a tablespoon of kalk wouldn’t be able to saturate the RO moving through the stirrer as long as a cup of kalk would). I’m not a chemistry wiz, but my thought is that something (maybe the high pH of the kalk water in the stirrer) keeps the excess kalk from mixing with the newly introduced RO, sort of like how media in a Ca reactor would be near useless without injecting CO2 to decrease pH.

I’m trying to think of mods to help with this problem. One I thought of is to add zip ties to the stirrer shaft to create more stirring action. However, I don’t know if this would really have any effect. My other thought was to add something to significantly lower the pH of the RO in my reservoir... maybe adding vinegar or PH Down or something else. Of course if I did, I would always have to run my top-off through the stirrer to avoid lowering my tank’s pH. Has anybody else dealt with this or come up with mods to address?

 

[ludnix]

Continuously supersaturating the kalkwasser with vinegar is an interesting idea. I imagine it could be done with the hardware from a c02 reactor so you could just shut off a solenoid providing vinegar based on the pH of the effluent.

 

[BeejReef]

Following. Having a similar issue with my ATO resevoir. The Kalk seems to lose potency after 3-4 days. My guess is that my lid is too drafty.

 

[Crashjack]

Continuously supersaturating the kalkwasser with vinegar is an interesting idea. I imagine it could be done with the hardware from a c02 reactor so you could just shut off a solenoid providing vinegar based on the pH of the effluent.

I wanted it to be simple, but if I did something like that, I would probably just inject CO2. Heck, I even thought about getting a long straw and blowing into it to add CO2. My preference is that whatever I do to be simple and at least somewhat automated.

Following. Having a similar issue with my ATO resevoir. The Kalk seems to lose potency after 3-4 days. My guess is that my lid is too drafty.

Air isn't supposed to be that big of factor. My stirrer doesn't have much surface area at the top so air should be even a smaller issue for me.

 

[ludnix]

I dont think you actually want much CO2 in there. I believe that is why you dont want to expose the kalkwasser to air, it turns in calcium carbonate and becomes insoluable.

I think the enitre point of the kalk stirrer is to reduce air exposure, where did you read it's not a big factor?

 

[Crashjack]

I dont think you actually want much CO2 in there. I believe that is why you dont want to expose the kalkwasser to air, it turns in calcium carbonate and becomes insoluable.

I think the enitre point of the kalk stirrer is to reduce air exposure, where did you read it's not a big factor?

From what I read, it would increase the solubility (e.g. make a stronger solution). I can’t find a definitive answer as to whether or not it would better utilize the kalk. My issue is, based on my evaporation rate, I’m adding enough kalk to last 2+ weeks. However, it isn’t lasting that long, and I don’t understand why but would like to make it last for 2 weeks.

 

[ludnix]

Can you remove the air from the stirrer? Being stirred and exposed to air may be converting it to calcium carbonate, randy has an article that explains the degradation here: http://reefkeeping.com/issues/2003-05/rhf/feature/index.htm

 

[Crashjack]

As I understand it, the article is pointing out:

1. Air has only a small effect on the degradation of kalk (in a reservoir or in a stirrer).
2. A stirrer is little if any more effective at protecting against the degradation of kalk as compared to using a reservoir.

As I read the article, the main reason a stirrer isn't more effective is because the effect of air is so minuscule in the first place when undisturbed kalk powder sits at the bottom of a reservoir or when kalk powder is stirred at the bottom of a stirrer. I used to make homemade wine, and the more surface area you expose to air, the more oxygen that will be absorbed into wine leading to oxidation. Though my stirrer likely allows for less surface area to be exposed than most reservoirs would, thereby allowing less air (CO2) to be absorbed, it doesn't really matter because the effect is so small in the first place, and it still has a significant exposure to air. Assuming all of this is correct, even if I could create a vacuum in my stirrer, it wouldn't make a huge difference.

I went ahead and did what I could to try to make my stirrer more effective and will try to remember to post results. What I did to my Avast K1 stirrer:

• The stirring blade is supposed to be about 1/8th" above the bottom. Once when the shaft holding the blade came loose, I re-seated but didn't measure the distance off the bottom. The blade was near touching (probably touching on one-side) so I raised the shaft a little, getting the blade close to that 1/8" off the bottom.
• I added (2) zip ties to the shaft just above the blade, lined-up one on top of the other, running parallel to each other. I cut these to where they were slightly shorter than the furthest distance of the blade so they wouldn't touch the inside walls of the stirrer. I did this to increase stirring action but without increasing to the point where kalk water in the stirrer remains cloudy.
• I added a John Guest clip to the Guest connector that holds the acrylic rod inside the stirrer. RO is pushed from the RO reservoir into the connector, into the rod, which releases RO into the lower 3rd of the stirrer but above where the kalk powder settles. My fear has always been that if the connection between the connector and the rod were to leak, RO would spill onto the surface of the kalk water and roll right out the overflow union/barb into the sump. If that happened, I would be adding diluted kalk if not almost straight RO into my sump. The clip just makes the connection that much more secure.

 

[mitch91175]

As I understand it, the article is pointing out:

1. Air has only a small effect on the degradation of kalk (in a reservoir or in a stirrer).
2. A stirrer is little if any more effective at protecting against the degradation of kalk as compared to using a reservoir.

As I read the article, the main reason a stirrer isn't more effective is because the effect of air is so minuscule in the first place when undisturbed kalk powder sits at the bottom of a reservoir or when kalk powder is stirred at the bottom of a stirrer. I used to make homemade wine, and the more surface area you expose to air, the more oxygen that will be absorbed into wine leading to oxidation. Though my stirrer likely allows for less surface area to be exposed than most reservoirs would, thereby allowing less air (CO2) to be absorbed, it doesn't really matter because the effect is so small in the first place, and it still has a significant exposure to air. Assuming all of this is correct, even if I could create a vacuum in my stirrer, it wouldn't make a huge difference.

I went ahead and did what I could to try to make my stirrer more effective and will try to remember to post results. What I did to my Avast K1 stirrer:

• The stirring blade is supposed to be about 1/8th" above the bottom. Once when the shaft holding the blade came loose, I re-seated but didn't measure the distance off the bottom. The blade was near touching (probably touching on one-side) so I raised the shaft a little, getting the blade close to that 1/8" off the bottom.
• I added (2) zip ties to the shaft just above the blade, lined-up one on top of the other, running parallel to each other. I cut these to where they were slightly shorter than the furthest distance of the blade so they wouldn't touch the inside walls of the stirrer. I did this to increase stirring action but without increasing to the point where kalk water in the stirrer remains cloudy.
• I added a John Guest clip to the Guest connector that holds the acrylic rod inside the stirrer. RO is pushed from the RO reservoir into the connector, into the rod, which releases RO into the lower 3rd of the stirrer but above where the kalk powder settles. My fear has always been that if the connection between the connector and the rod were to leak, RO would spill onto the surface of the kalk water and roll right out the overflow union/barb into the sump. If that happened, I would be adding diluted kalk if not almost straight RO into my sump. The clip just makes the connection that much more secure.

Interested in your findings on this. I just implemented a kalk stirrer again but went with a much better one this time around. I had a Reef Octopus before but this time around I have a Geo Reef. This is much better built than the Reef Octopus and looks to be exactly what I needed.

 

[Graffiti Spot]

I made my own stirrer because most had features I didn’t like.
Mine has a larger chamber, 6 by 18 and I use a mesh piece to help stir along with extra stirrer bars higher up.
The ro water enters through the kalk at the bottom making sure every bit is saturated. The kalk rises and fluffs up each time it enters the chamber. This is the main thing I think all stirrers need to be most effective, especially for large tanks. I installed a fill tube on the side with a valve at the top that prevents water from syphoning. The fill tube is a 1” pipe at the connection to the stirrer and then jumps to 1.5” pipe on the riser with the one way valve at the top.
I can fill it with dry kalk 1/4 of the way up before I add water since the chamber is so large and this also helps avoid changing kalk every two or three weeks, I can run it without adding kalk for months and topping it off with newer kalk pushes it even farther. It’s a big stirrer but does 100 percent of what I need it too.

 

[DangerDave]

Same, big stirrer and a lot of kalk. It lasts a long time, and I just top it off when needed.

I take it down and rinse out every few months. I don’t think I need to do this though, it rinses clean very easily, and it feels like I’m wasting kalk.

 

[FlyPenFly]

You can use a magnetic stirrer that won’t break the water surface.

Or you could just make saturated kalk in a mixing jug, and then fill a dosing container with little to no precipitate and dose that, which should be very consistent.

 

[Crashjack]

Interested in your findings on this.

I've run this way for one month, and I'll convey what I'm seeing so far. First, I've got a 142 gal tank by dimensions (6' x 2' x 19") and a Trigger 39 sump (40 gal sump). All kalk additions are via water top-off (I don't dose). I estimate my total water volume to be around 130 gal. My evaporation rate varies but when I did put a little effort in calculating it, my evaporation rate averaged around 1.25 gal/day. I have my RO reservoir running to a 3-way valve, which allows me to manually switch between running RO through the stirrer or bypassing the stirrer and running straight RO. Hence, I can run kalk 24/7, or only at night, or 16 hrs./day, or however long I want; I just have to manually turn the valve. That said, I keep my kalk schedule consistent unless alk testing tells me I need to run more or less kalk (if I'm running any kalk, I always run overnight and then adjust from there). I'm testing alk 2 times per week and when alk testing dictates, I adjust the length of time I run daily kalk and then test a few days later. I also log all test readings, kalk additions, changes to how long I run daily kalk, etc. I perform 15% water changes every 14 days. With every water change, I alternate cleaning stirrer and adding kalk, and adding kalk on top of what is already in the stirrer (each addition is a little shy of 1.5 cups of kalk). My tank is lightly stocked with LPS and SPS corals, and no clams.

What I'm seeing so far is that the initial fill (done when I clean the stirrer) is very potent and lasts the full two weeks. Running a 12 hr/day schedule, my alk showed an average increase of .1 dkh per day with the highest reading being day 13, which was the day before my next w/c and the addition of more kalk. However, after the w/c and adding kalk on top of the kalk that was already in the stirrer, I saw an average drop of .133 dkh/day so I increased running kalk to about 18 hrs./day. I then saw a an average drop of .15 dkh/day so I started running kalk 24/7. I also added about .2 dkh worth of sodium bicarbonate at this time. Three days later, my alk measured .1 dkh lower. Now, the anomaly is that I was treating Bryopsis with a full-dose of Fluconzole the first two weeks with no skimmer, UV, or carbon, and my corals weren't looking very good. The second two weeks, the Fluconzole was diluted by the 15% w/c. I still wasn't running skimmer, UV, or carbon, but my corals were progressively looking better. However, I get 24/7 pH readings via my controller, and my pH highs/lows stayed pretty consistent the first two weeks but progressively decreased the second two weeks. I'm not a reef chemistry guru by any stretch, but even if my corals were utilizing a lot more alk the second two weeks, I don't think that would reduce pH, especially with me running kalk a lot longer every day during the second two weeks.

My w/c was Wednesday (3 days ago), and I cleaned stirrer and added kalk at that time. Today will be my first alk test after that w/c. I think this next 4 weeks will tell me a lot.

 

[FlyPenFly]

I would just get a $80 Bluetooth single channel doser and dose saturated Kalk, it’ll be much more consistent and stable. It will also be much safer than relying on an ATO that might dump.

 

[mitch91175]

I would just get a $80 Bluetooth single channel doser and dose saturated Kalk, it’ll be much more consistent and stable. It will also be much safer than relying on an ATO that might dump.

Yeah I just put in a kalk stirrer being feed by a Neptune DOS. Going to see how that setup does. First signs are looking promising.

 

[mitch91175]

 

[Crashjack]

For me, dosing is no safer than running via my ATO (exact same failsafes). My plan from the start of this tank has been to see how far kalk will take me and then go from there. To me, the disadvantage of dosing is that unless you calibrate often and pay a lot of attention, you don't really know what you are getting. For instance, if the tubing cracked or something occurred to where it wasn't dosing, it would take a while to figure out because the water level would still remain constant. I would eventually discover due to lower pH or with alk testing, but tied to my ATO, water level and warnings let me know if I'm not topping-up right away. I agree that dosing should keep Alk more stable, but that also assumes the doser always doses the same amount. That said, I might wind up dosing at some point. It really just depends on how I want to deal with Alk/Ca once kalk alone can't handle.

 

[FlyPenFly]

Doser are far far more reliable and consistent than ato.

 

[Crashjack]

Doser are far far more reliable and consistent than ato.

Theoretically, more consistent in that you can spread your dosing out in exact time increments. However, you make the assumption that your doser dumps the same volume every time. Assuming you can set the sensitivity of your ATO (I can in my system), you still spread out over the course of a day. In fact, assuming more evaporation during daylight hours, your ATO would naturally add more kalk when more is needed (also assuming you are running kalk 24/7).

Safer? In some systems maybe, but not in mine. My ATO runs off a dosing pump that is programmed to shut-off after a user defined # of minutes, and I also shut-off and get a warning based on a user set pH value. I would use the same failsafes with dosing.

 

[mitch91175]

I have my kalk stirrer setup with a pH probe in it. My pH averages 12.4 in the stirrer. I figure as long as it is above 12 that I'll be dosing saturated kalk. I know that it is saturated with dosing and increases that I see if I increase the dosage.

The Geo Reef kalk stirrer is much, much better than the Reef Octopus that I had. Yes it is a little more $$$, but I'd make the purchase again in a heartbeat.