Potential problems with Dripping Kalk

[bqq100]

Right now I am adding kalk to my ATO bucket, but after a close call (due to my own carelessness) while I was out of town for 10 days, I'm considering switching to dripping kalk instead.  Here are some of the concerns I have for making the switch, but I think the pros outweigh the cons...

 

• Line clogs and drip stops - Can help mitigate by making sure container is free of precipitate by pre-mixing in a second container and periodically cleaning the end of the tube.  Even if the drip stops for a day or 2, my usage is low enough where it shouldn't be a major issue.
• Overdose due to valve failure - Can needle/ball valves fail in the open position?  Regardless , I think I will control the drip with both a needle and ball valve for better control of drip rate
• Changing drip rate - Keeping container/end of tube clean should help prevent this.  Will still change with changing level in container, but this is still much better control than with my current ATO/kalk setup.
• Limited reservoir capacity - I can fit a 1 gallon reservoir in my stand for dripping.  Right now I think I need ~.45 gallons of saturated kalk per week.  2 weeks is great, but even if my consumption rate doubles and I only get 1 week I think I'll still be happy.
• No remote control - Can't turn on/off through my APEX, but this is more of a nice to have than anything.

Any other issues I should look out for?

[Der ABT]

best way to mitigate problems is to not put enough kalk in to nuke the tank

 

otherwise a dosing pump not a drip rate.......

[bqq100]

best way to mitigate problems is to not put enough kalk in to nuke the tank

 

otherwise a dosing pump not a drip rate.......

 

Any idea on how much kalk would nuke the tank?

[Brian Ward]

Really depends on the size of the tank. Mixing with your topoff water can be dangerous b/c your evap rate will vary throughout the year while your kalk consumption (actually alk/ca) will vary by the size and variety of corals in your tank.

 

Would recommend going with a kalk stirrer or doing 2-part with a dosing pump to ensure control over how much is going in. Dripping is extremely prone to human error as you've noted. Whenever I've heard of people dripping kalk, it has always been a 1-time mix and drip while watching/monitoring the tank only.

[gmerek2]

A lot of newbies like me dose kalk aimlessly (like me) because everyones doing it.  well my test kits finally came and my calcium was high and alk low Mg high. I have very little calcium consumption apparently (little corals/clams) Sometimes my kalk is freshly stirred, not settled and ATO pumps it in, clouding my tank. My corals seem to like it when it happens lol. But this may be part of my problem with high calcium. I dont think my ATO pumps in enough top off water/kalk to affect the 155 gallons its dosing. But with time I almost overdosed my tank with calcium. test test test

[bqq100]

Really depends on the size of the tank. Mixing with your topoff water can be dangerous b/c your evap rate will vary throughout the year while your kalk consumption (actually alk/ca) will vary by the size and variety of corals in your tank.

 

Would recommend going with a kalk stirrer or doing 2-part with a dosing pump to ensure control over how much is going in. Dripping is extremely prone to human error as you've noted. Whenever I've heard of people dripping kalk, it has always been a 1-time mix and drip while watching/monitoring the tank only.

 

Kalk stirrer won't fit in my stand, and 2 dosing pumps seems like overkill for the little amount of 2 part I need to add.  I wonder how bad things would get if 1 gallon of saturated kalk was dumped into a 29 gallon system.

 

A lot of newbies like me dose kalk aimlessly (like me) because everyones doing it.  well my test kits finally came and my calcium was high and alk low Mg high. I have very little calcium consumption apparently (little corals/clams) Sometimes my kalk is freshly stirred, not settled and ATO pumps it in, clouding my tank. My corals seem to like it when it happens lol. But this may be part of my problem with high calcium. I dont think my ATO pumps in enough top off water/kalk to affect the 155 gallons its dosing. But with time I almost overdosed my tank with calcium. test test test

 

I agree, using it in ATO water seems pretty aimless.  I have been testing Alk/Ca frequently.  My first couple of batches of kalk topoff water weren't enough, and I'm pretty sure my current batch is too much.  I feel like dripping it will give me much better control over how much is added over the course of a week.

[countryboy]

I add mine manually every morning. NO FUSS NO MUSS

[Origami]

A lot of newbies like me dose kalk aimlessly (like me) because everyones doing it.  well my test kits finally came and my calcium was high and alk low Mg high. I have very little calcium consumption apparently (little corals/clams) Sometimes my kalk is freshly stirred, not settled and ATO pumps it in, clouding my tank. My corals seem to like it when it happens lol. But this may be part of my problem with high calcium. I dont think my ATO pumps in enough top off water/kalk to affect the 155 gallons its dosing. But with time I almost overdosed my tank with calcium. test test test

 

Kalkwasser is a balanced additive. That is, it delivers BOTH calcium and alkalinity to your tank in the approximate proportions needed to build coral skeletons. It does not have magnesium in it, unless it's an impurity. And, it does not, in the short term, result in a calcium / alkalinity / magnesium imbalance like you describe. If you're getting an imbalance, it's either because you started with one, you're dosing another calcium additive, you're dosing it wrong, or (in a more rare case) you have high nitrates and are trying to manage it through big water changes.

 

"Kalk" powder is really calcium hydroxide (chemical formula Ca(OH)₂. In the presence of water and carbon dioxide, it does this:

 

Ca(OH)₂ + 2 H₂0 + CO₂ ==>> Ca²⁺ 2 HCO₃^-  (That is, one calcium ion and two bicarbonate ions, which is equal to the proportion that they are used when corals form their calcium carbonate skeletons.)

 

Calcium hydroxide also has very low solubility in water. That's why you can only dissolve a couple of teaspoons or so into a gallon of water, with the rest settling to the bottom of the container. Kalkwasser is the somewhat clear effluent that is water saturated with the kalk powder (minus the settled, undissolved powder) That's the stuff that you want to dose. If you add the powder, you're giving your tank a dose of some very potent stuff (just a teaspoon of it's equal to about a gallon of kalkwasser, remember).

 

The interesting thing about what you described, that is, high calcium, low alkalinity, and low magnesium, points to the possibility that you may be dosing kalkwasser (or the settlement) too quickly into a low-flow area of your tank and, in the process, may be precipitating out magnesium hydroxide (milk of magnesia). This would consume both magnesium and alkalinity, leaving behind the calcium.

 

Final note: Kalkwasser is always made with fresh water. Never run a kalk stirrer off of salt water from your tank because it will suck the magnesium right out of the water (and give you a high dose of calcium without the corresponding alkalinity).

[gmerek2]

Sounds like my problem. Taking a break from kalk and bumping up water change. Then I'm going to change my kalk habits to see where parameters go. (mixing in separate container let settle and pump clear part into top off container) there were a few things I need to question about what is happening from my dosing mistakes. My Mg is high I must have expressed that wrong it is not low. I dosed Mg in top off separately according to directions blindly without testing. With little coral consumption I felt like it accumulated. Is that possible? Maybe just some mg was absorbed with precip. I searched all over the Internet trying to figure out how my Alk went low so fast but that is solved now I think it was the precipitation of magnesium hydroxide absorbing it. Now is the Alk dosed/used out of that settled kalk? is it still kalk or pretty much just calcium laying there? Because that also would explain how I'm getting extra calcium in tank.

[Origami]

Sounds like my problem. Taking a break from kalk and bumping up water change. Then I'm going to change my kalk habits to see where parameters go. (mixing in separate container let settle and pump clear part into top off container) there were a few things I need to question about what is happening from my dosing mistakes. My Mg is high I must have expressed that wrong it is not low. I dosed Mg in top off separately according to directions blindly without testing. With little coral consumption I felt like it accumulated. Is that possible? Maybe just some mg was absorbed with precip. I searched all over the Internet trying to figure out how my Alk went low so fast but that is solved now I think it was the precipitation of magnesium hydroxide absorbing it. Now is the Alk dosed/used out of that settled kalk? is it still kalk or pretty much just calcium laying there? Because that also would explain how I'm getting extra calcium in tank.

At the risk of hijacking bqq100's thread, let me touch on your points. But if we go further, it might be good to start another thread.

 

Kalk, despite how it sounds like "calc," provides BOTH calcium and alkalinity. It's like both major parts of two-part in one. Chemically, it's "calcium hydroxide." The hydroxide part is alkalinity. Unfortunately, kalk powder's not very soluble - that is, it doesn't take much for it to saturate in water. The CRC handbook says, for example, that only 1.85 grams of it will dissolve in 1 liter of water at 0 degrees C. This drops at higher temperature to 0.77 grmas per liter at 100 degrees C. When you mix a couple of teaspoons of kalk into some RO/DI water, some will always settle out to the bottom. Generally speaking, this is unused calcium hydroxide. So if you were to siphon off some of the clear effluent and replace it with new RO/DI water, this reservoir of unused kalk would dissolve. That's the operating principle behind kalk stirrers. BTW, saturated kalk effluent has an alkalinity concentration of about 40.8 meq/liter and a calcium concentration of 808 ppm. If kalkwasser were to sit around too long in the open air, it's calcium and alkalinity might react just a little bit with atomospheric CO2 to form a thin skin of calcium carbonate. Most of the time this is not a problem.

 

As for your magnesium levels, yes, it's more than possible to overdose it if you're not measuring for it. A word to the wise: Don't dose if you don't test. Luckily, magnesium is one of those ions that has a wide range of acceptability from as low as 1100 ppm to as high as 1700 ppm, with the "nominal" being around 1280 ppm. Corals do consume magnesium, but in varying proportions. Randy Holmes Farley wrote a good article on magnesium a few years back.