dKH rising steadily

[Djplus1]

So, my Kalkstirrer went live 5/31 and brought my dKH from 6.5 (measured 5/31, day after water change and before bringing kalk online) to 7.1 on 6/1, 7.8 on 6/2, 8.1 on 6/3, 8.5 on 6/6 (directly before water change) and 9.0 today (6/9). It's being administered through ATO and pH has averaged 8.16 per Apex.

 

Just curious what folks have experienced when utilizing kalkwasser? As you can see, my #'s just keep steadily increasing. When will it effectively level out as I can't imagine it's just going to keep rising past 12 (or is it?) FWIW, I ran this stirrer on my old tank 10 years ago and never had any issues, though I did not really test for dKH regularly either if much at all.

[DaJMasta]

It could be that the kalk is more concentrated (higher flow through? ), or that it's just running a lot more or even that the lower dkh period also had somewhat reduced consumption that hasn't fully recovered.  Maybe the pH benefits could also contribute there.

 

If you've got your controller set to stop it at a certain pH or dKH (or both), you can prevent any risk of overdosing, but you could also just set it to administer a set amount that you know is under consumption and fill in the rest manually or with two part or something. 

[Djplus1]

29 minutes ago, DaJMasta said:

It could be that the kalk is more concentrated (higher flow through? ), or that it's just running a lot more or even that the lower dkh period also had somewhat reduced consumption that hasn't fully recovered.  Maybe the pH benefits could also contribute there.

 

If you've got your controller set to stop it at a certain pH or dKH (or both), you can prevent any risk of overdosing, but you could also just set it to administer a set amount that you know is under consumption and fill in the rest manually or with two part or something. 

I don't have anything monitoring dKH, so I'm doing it via Hanna pretty much every couple few days. I honestly think it should eventually sit at a number within a few days or so, but I do need to have an emergency cut off time where I need to pull off the kalk stirrer if I don't see that leveling off. Do you think I should watch for a certain # like 11.5 or 12 and just yank off the stirrer?

[YHSublime]

I’d stop doing so much. Personally I’d pull the 2 part for 48 hours and test to see what Consumption looks like over that time period, then adjust accordingly. 
 

are you using a dosing calculator?

did you mix up the ESV with RO by weight, or oz?

[Djplus1]

34 minutes ago, YHSublime said:

I’d stop doing so much. Personally I’d pull the 2 part for 48 hours and test to see what Consumption looks like over that time period, then adjust accordingly. 
 

are you using a dosing calculator?

did you mix up the ESV with RO by weight, or oz?

I'm not dosing yet. Just the kalkwasser. I was tracking usage to start dosing eventually, but clearly going higher than expected....

[YHSublime]

I’ve never used kalk, but I’d probably dilute it, is it’ll getting added with top off?

[DaJMasta]

You can just turn it on/off with a timer until you find a good balance and then readjust it after testing - basically what I do with a reservoir and a dosing pump.

 

I'd stop it around 11, tops, not because it can't go over, but because you want some extra margin.  If you've got a pH measurement, that can be used a little bit as a proxy - kalkwasser also raises pH (far more than other alkalinity supplements), so putting a modest ceiling on that should help dose a bit less (and will encourage dosing when the lights aren't on, which can help keep pH up at night.)

 

It's worth mentioning that I don't think the kalk stirrer is supposed to be an always on device unless the flow through it is already inadequate to meet tank demands.  Using it with a timer or better yet in a control loop is a better choice, at least until you're using up so much alkalinity that the consumption is consistently more than what the stirrer can supply.  In a shorter term, it could even just mean using a valve to reduce the flow from the pump into it.

[WheresTheReef]

Isn't your tank fairly new? Do you have any corals in there, if so what kind? If your tank is new, there will be some dkh drop due to an incomplete nitrogen cycle. Once the slow anaerobic bacteria establishes, the dkh drop due to cycling will drop off. In the past, I ran LPS tanks without even dosing with regular water changes. When dosing anything, I always find it's best to do it manually until you find the consumption rate with testing. Since the levels are rising, you're dosing more than your tank is consuming.

[Djplus1]

12 hours ago, YHSublime said:

I’ve never used kalk, but I’d probably dilute it, is it’ll getting added with top off?

It is administered via top off. I'm using the recommended 1/2 cup of kalk per the Avast instructions supposedly added every 2 weeks. I will monitor dKH until this Saturday when I would in theory add more and if it hasn't stopped rising, I will not add another half cup and maybe wait another week to only add 1/4 cup.....

[Djplus1]

8 hours ago, DaJMasta said:

You can just turn it on/off with a timer until you find a good balance and then readjust it after testing - basically what I do with a reservoir and a dosing pump.

 

I'd stop it around 11, tops, not because it can't go over, but because you want some extra margin.  If you've got a pH measurement, that can be used a little bit as a proxy - kalkwasser also raises pH (far more than other alkalinity supplements), so putting a modest ceiling on that should help dose a bit less (and will encourage dosing when the lights aren't on, which can help keep pH up at night.)

 

It's worth mentioning that I don't think the kalk stirrer is supposed to be an always on device unless the flow through it is already inadequate to meet tank demands.  Using it with a timer or better yet in a control loop is a better choice, at least until you're using up so much alkalinity that the consumption is consistently more than what the stirrer can supply.  In a shorter term, it could even just mean using a valve to reduce the flow from the pump into it.

Unfortunately I can't set it on a timer as it's directly connected up to my ATO and gravity fed. As far as PH goes, aside from the immediate spikes (reading up to 8.5 or so for a minute give or take, where the top off enters the baffle chamber ahead of my return and ph probe) it's a steady 8.1-8.2 all day. And there are definitely plenty of people using kalkwasser full time, myself included for years on end. I've actually never dosed 2 part since I didn't need it, but was hoping to incorporate the kalk AND 2 part this time around to promote growth.

[Djplus1]

1 hour ago, WheresTheReef said:

Isn't your tank fairly new? Do you have any corals in there, if so what kind? If your tank is new, there will be some dkh drop due to an incomplete nitrogen cycle. Once the slow anaerobic bacteria establishes, the dkh drop due to cycling will drop off. In the past, I ran LPS tanks without even dosing with regular water changes. When dosing anything, I always find it's best to do it manually until you find the consumption rate with testing. Since the levels are rising, you're dosing more than your tank is consuming.

It is pretty new, but it already has a decent bit of coral. Three torches (2x heads each), Four Hammers (2-4x heads each), One 2x head Bowerbanki, three Acan frags, two gonioporas, one alveopora, one 8x head duncan, one funghia, one tubbs stellata monti mini colony, one forest fire digi frag, and a couple random plating and encrusting monti frags. This started with me losing a torch and corals not looking so great when I discovered my dKH was at 6  and for who knows how long as I couldn't figure out exactly where I was with the Red Sea test and the moment I got the Hanna, I've been able to track MUCH more efficiently. 

 

I'm hoping that over the next few days it just hovers around 9 which I'd be happy with, but I'm just trying to get ahead of what happens when it just keeps rising and rising a decimal point or 2 each day. I just don't want to pull it off and dwindle back down to where I started as that solves nothing.

[DaJMasta]

2 hours ago, Djplus1 said:

Unfortunately I can't set it on a timer as it's directly connected up to my ATO and gravity fed. As far as PH goes, aside from the immediate spikes (reading up to 8.5 or so for a minute give or take, where the top off enters the baffle chamber ahead of my return and ph probe) it's a steady 8.1-8.2 all day. And there are definitely plenty of people using kalkwasser full time, myself included for years on end. I've actually never dosed 2 part since I didn't need it, but was hoping to incorporate the kalk AND 2 part this time around to promote growth.

 

With that methodology, this is going to be the expected outcome a good portion of the time.  Without a way to control the amount of input, a continuous stream of kalk is still a form of dosing and can overdose in time if not controlled or if growth doesn't yet outpace it.  Generally speaking, increasing parameters are also probably not ideal stability for maximum growth, so it's unlikely the tank will start consuming all of what's added before the alkalinity climbs to a problematic level.

 

If it's gotta be on all the time, I would either let it just run without kalk for a bit after depleting (only works well if you don't get too far over your target before this batch runs out), if you add some plain RO daily to the tank (to reduce the runtime of the ATO), or use less kalk in the stirrer when it resets.
 

You could also try humidifying the room (probably not a good idea) or covering some of the tank/sump to reduce evaporation (and thus reduce ATO runtime.)  It's likely that in the winter your kalk dose will increase because the dry air makes the ATO run more often, so by dosing in the ATO, you have an inherently variable dosing method.

[Djplus1]

27 minutes ago, DaJMasta said:

 

With that methodology, this is going to be the expected outcome a good portion of the time.  Without a way to control the amount of input, a continuous stream of kalk is still a form of dosing and can overdose in time if not controlled or if growth doesn't yet outpace it.  Generally speaking, increasing parameters are also probably not ideal stability for maximum growth, so it's unlikely the tank will start consuming all of what's added before the alkalinity climbs to a problematic level.

 

If it's gotta be on all the time, I would either let it just run without kalk for a bit after depleting (only works well if you don't get too far over your target before this batch runs out), if you add some plain RO daily to the tank (to reduce the runtime of the ATO), or use less kalk in the stirrer when it resets.
 

You could also try humidifying the room (probably not a good idea) or covering some of the tank/sump to reduce evaporation (and thus reduce ATO runtime.)  It's likely that in the winter your kalk dose will increase because the dry air makes the ATO run more often, so by dosing in the ATO, you have an inherently variable dosing method.

Yeah, that's kind of the point of the post. I definitely see that constantly rising levels of any type are problematic. I'm just hoping that since the stirrer has only been on a week that this is the "strongest" it's going to be and will slowly just "settle" at some point I'm comfortable with (hopefully shortly) so I can just go back to relying on my numbers not getting out of whack  over a week without me realizing.

 

Would adding top off water manually here and there to reduce the ATO usage really do anything other than delay the inevitable rise in dKH until I just cleaned out the stirrer with a less potent solution? Or are you implying the solution will weaken enough where this is a good time buffer of sorts?

 

I do plan on watching the dKH level every day this week and see if I notice any kind of levelling off before making the call to take the stirrer offline this weekend and washing it out and starting again in a few days to get back down towards 8-9, with half of the suggested kalk powder and see how that goes.

[DaJMasta]

The thing that will make the continuous addition fine is the growth of the coral (and their consumption as a result), so the delay is what stops it from being inevitable.  If you can add regular RO for long enough that your system starts consuming more alkalinity than the continuous kalk can provide, then you've delayed long enough to just let it run.  The only caveat here is that it could take weeks or months depending on how much kalkwasser is actually being added.  This is, of course, provided your system has enough stony corals that are happy enough that they'll need it all, but I think this is pretty likely.

 

I think the design of the kalk stirrers is such that they stir it explicitly to make a fully concentrated solution, so it is unlikely that the concentration will go down unless the level of kalk powder in there drops to below what's required.  That said, especially if you're checking regularly, you could just turn off the stirrer.  If it's not stirred, you get way less dissolving into the water that passes through and should pretty dramatically decrease the concentration of the solution entering the tank, while adding at least a bit.

[Djplus1]

1 minute ago, DaJMasta said:

The thing that will make the continuous addition fine is the growth of the coral (and their consumption as a result), so the delay is what stops it from being inevitable.  If you can add regular RO for long enough that your system starts consuming more alkalinity than the continuous kalk can provide, then you've delayed long enough to just let it run.  The only caveat here is that it could take weeks or months depending on how much kalkwasser is actually being added.  This is, of course, provided your system has enough stony corals that are happy enough that they'll need it all, but I think this is pretty likely.

 

I think the design of the kalk stirrers is such that they stir it explicitly to make a fully concentrated solution, so it is unlikely that the concentration will go down unless the level of kalk powder in there drops to below what's required.  That said, especially if you're checking regularly, you could just turn off the stirrer.  If it's not stirred, you get way less dissolving into the water that passes through and should pretty dramatically decrease the concentration of the solution entering the tank, while adding at least a bit.

That's a good idea, I didn't think of turning off the stirrer motor. I may try that. However, I may have a positive update as I just now did a test and my dKH was 8.9, and my top off just happened about 30 minutes previous. This is the first time that the number did not increase, so perhaps I am going to settle somewhere between 8-9 when all is said and done.

[Origami]

I've run kalkwasser on and off for decades. Here are my observations.

 

Kalk is a balanced additive. It provides both alkalinity and calcium in the basic 2:1 ratio needed for the hard coral (i.e., SPS) skeleton formation.

• Details: This ratio is an over-simplication as it doesn't reflect the content of magnesium and strontium in these skeletons. But it's still a good rule-of-thumb for understanding.

Kalk (aka calcium hydroxide, or slaked lime) saturates in fresh water at a very, very low level. This limits how much alkalinity you can dose per day.

• Details: 1.89 grams per liter of fresh water at 0 degrees C, down to 0.77 grams per liter at 100 degrees C. At 25 degrees C (77 F), solubility is 1.59 grams per liter. It's solubility and pH are so well known and happens at such low concentrations that it is actually considered a relatively good standard for pH calibration at high pH levels (pH of 12.54 at room temperature, 77F).  It also means that, if you're not running the stirrer in your kalkwasser reactor, you may not have good control of the concentration of the solution. This is IMPORTANT. When stirred with all particulates settled out, a liter kalkwasser is saturated and, at 77F, delivers 808 ppm of calcium and 40.8 milliequivalents of alkalinity to your tank. (Of course, that's diluted by the volume of your tank).  That limitation means that, when administered as part of a top-off system (that compensates for evaporation), evaporation limits how much alkalinity you can dose in a day. 

This limitation may not be a factor in new systems without much consumption (i.e., calcium carbonate (hard coral skeleton) deposition / formation), but in systems with high consumption, is likely to be insufficient and will require additional supplementation (e.g., calcium reactor or two-part dosing). 

• For example, let's say that a 100 gallon (378.541 liters) system evaporates 1 gallon (3.78541 liters) of fresh water per day, and that you're replacing that evaporation with saturated kalkwasser. That means you're adding about 6 grams of kalk total per day - that's enough to form about 8 grams of coral skeleton (calcium carbonate) or about 3 cubic centimeters of skeleton (at most, assuming of the consumption goes to skeleton formation). 

If your goal is to maintain stable calcium and alkalinity parameters (and it should be once you've reached your targets), then supplementation = consumption. That is, replace what is used. Anything more, and levels in your water will increase. Anything less, and the levels go down.

• Details:You can use these "trends" in your test measurements to estimate consumption. Over the long term, if you've got corals that are growing and increasing in size, consumption will go up and demands on your supplementation methods will increase.

Following this, if you find that your levels are increasing, you need to add less kalkwasser (or increase consumption). Here's the thing, though, if you're adding it as part of your ATO and your evaporation rate is high enough that you're delivering more than is needed, then you basically need to add less kalkwasser. This means less ATO water through the kalkwasser reactor. You really can't - or shouldn't - try adjusting the stirrer on/off times. That's basically going to be a crapshoot as you won't be able to reliably control the concentration of the dissolved kalk in solution (which is one of the key reasons kalkwasser was once highly regarded in the hobby) and you're likely to see your levels fluctuate without much control. You CAN adjust how much ATO water is going through the reactor, but is you're basically running all your ATO through the reactor, reducing this (without compensating with ATO that bypasses the reactor) will only reduce your water level and raise ion concentrations (i.e., salinity).

 

One solution is to abandon kalkwasser for now and move to a two-part approach. Another is to add only as much kalkwasser as is needed, and to supplement the rest of your ATO with fresh water that bypasses the ATO. A third approach is to manage your parameters with water changes during this time when your tank is reasonably young without much growth, and then to switch over to kalk when things are growing more. And yet another is to increase consumption (adding larger, fast-growing corals, changing light management to increase growth, etc.). The first two approaches may require you to invest in dosing pumps, the second being very popular even today. The third was an approach used often a couple of decades ago. (It's still valid.) 

 

To reestablish your levels, though, will require that you take your kalk reactor offline (that is, bypass it in your ATO setup) and to let your levels drift down to your target levels. If the system is small enough, you can perform water changes to help move things along. 

 

I'm sure that I've missed a few things that I've learned over the years. But, while kalk is great (inexpensive, fairly simple, low-investment setup), I'd encourage you to look at the difficult parts of it. Namely, limited alkalinity delivery (due to low saturation level) and accidental overdosing. The first of these requires that you will eventually make additional investments in other delivery methods while the second means you'll be investing in additional hardware and complexity to manage/reduce the risk of an accident. I still hold kalkwasser in very high regard, but you should go into it with open eyes. 

 

 

 

 

[Djplus1]

1 hour ago, Origami said:

I've run kalkwasser on and off for decades. Here are my observations.

 

Kalk is a balanced additive. It provides both alkalinity and calcium in the basic 2:1 ratio needed for the hard coral (i.e., SPS) skeleton formation.

• Details: This ratio is an over-simplication as it doesn't reflect the content of magnesium and strontium in these skeletons. But it's still a good rule-of-thumb for understanding.

Kalk (aka calcium hydroxide, or slaked lime) saturates in fresh water at a very, very low level. This limits how much alkalinity you can dose per day.

• Details: 1.89 grams per liter of fresh water at 0 degrees C, down to 0.77 grams per liter at 100 degrees C. At 25 degrees C (77 F), solubility is 1.59 grams per liter. It's solubility and pH are so well known and happens at such low concentrations that it is actually considered a relatively good standard for pH calibration at high pH levels (pH of 12.54 at room temperature, 77F).  It also means that, if you're not running the stirrer in your kalkwasser reactor, you may not have good control of the concentration of the solution. This is IMPORTANT. When stirred with all particulates settled out, a liter kalkwasser is saturated and, at 77F, delivers 808 ppm of calcium and 40.8 milliequivalents of alkalinity to your tank. (Of course, that's diluted by the volume of your tank).  That limitation means that, when administered as part of a top-off system (that compensates for evaporation), evaporation limits how much alkalinity you can dose in a day. 

This limitation may not be a factor in new systems without much consumption (i.e., calcium carbonate (hard coral skeleton) deposition / formation), but in systems with high consumption, is likely to be insufficient and will require additional supplementation (e.g., calcium reactor or two-part dosing). 

• For example, let's say that a 100 gallon (378.541 liters) system evaporates 1 gallon (3.78541 liters) of fresh water per day, and that you're replacing that evaporation with saturated kalkwasser. That means you're adding about 6 grams of kalk total per day - that's enough to form about 8 grams of coral skeleton (calcium carbonate) or about 3 cubic centimeters of skeleton (at most, assuming of the consumption goes to skeleton formation). 

If your goal is to maintain stable calcium and alkalinity parameters (and it should be once you've reached your targets), then supplementation = consumption. That is, replace what is used. Anything more, and levels in your water will increase. Anything less, and the levels go down.

• Details:You can use these "trends" in your test measurements to estimate consumption. Over the long term, if you've got corals that are growing and increasing in size, consumption will go up and demands on your supplementation methods will increase.

Following this, if you find that your levels are increasing, you need to add less kalkwasser (or increase consumption). Here's the thing, though, if you're adding it as part of your ATO and your evaporation rate is high enough that you're delivering more than is needed, then you basically need to add less kalkwasser. This means less ATO water through the kalkwasser reactor. You really can't - or shouldn't - try adjusting the stirrer on/off times. That's basically going to be a crapshoot as you won't be able to reliably control the concentration of the dissolved kalk in solution (which is one of the key reasons kalkwasser was once highly regarded in the hobby) and you're likely to see your levels fluctuate without much control. You CAN adjust how much ATO water is going through the reactor, but is you're basically running all your ATO through the reactor, reducing this (without compensating with ATO that bypasses the reactor) will only reduce your water level and raise ion concentrations (i.e., salinity).

 

One solution is to abandon kalkwasser for now and move to a two-part approach. Another is to add only as much kalkwasser as is needed, and to supplement the rest of your ATO with fresh water that bypasses the ATO. A third approach is to manage your parameters with water changes during this time when your tank is reasonably young without much growth, and then to switch over to kalk when things are growing more. And yet another is to increase consumption (adding larger, fast-growing corals, changing light management to increase growth, etc.). The first two approaches may require you to invest in dosing pumps, the second being very popular even today. The third was an approach used often a couple of decades ago. (It's still valid.) 

 

To reestablish your levels, though, will require that you take your kalk reactor offline (that is, bypass it in your ATO setup) and to let your levels drift down to your target levels. If the system is small enough, you can perform water changes to help move things along. 

 

I'm sure that I've missed a few things that I've learned over the years. But, while kalk is great (inexpensive, fairly simple, low-investment setup), I'd encourage you to look at the difficult parts of it. Namely, limited alkalinity delivery (due to low saturation level) and accidental overdosing. The first of these requires that you will eventually make additional investments in other delivery methods while the second means you'll be investing in additional hardware and complexity to manage/reduce the risk of an accident. I still hold kalkwasser in very high regard, but you should go into it with open eyes. 

 

 

 

 

Good read Tom. I'm definitely going in eyes open as I've used kalk in the past with decent results, but clearly need to keep an eye on what's currently going in as I absolutely do not want an over dose. I am picking up a couple more alk hungry sps this weekend, so hopefully that helps too, lol. I did buy Isaac's doser's a couple weeks ago and if the kalk is too much, I'm prepared to switch over to 2 part pretty quickly. I did just get a DKH result that wasn't trending upwards today, so I may actually have lucked out and leveled off now. Finger's crossed...