Does kalkwasser mix ever go bad?

[19Mateo83]

I just found two containers of KNOP brand kalkwasser powder from my previous reef tank. They have been in storage for 12 + years. Is there any reason to assume there is anything wrong with these? One is unopened and the other is almost full. Does this stuff go bad? Also does KNOP even make aquarium products anymore? @Randy Holmes-Farley

 

[Saltyreef]

If its not rock solid, its still good!

 

[fishyjoes]

I don't use kalkwasser, but I saw a video somewhere you have to keep it sealed because the CO2 in the air can get to it and make it less potent. I'll link the video if I can find it again.

 

[Randy Holmes-Farley Verified Community Expert]

CO2 will slowly enter and convert it into calcium carbonate. It might still be usable, if far less potent.

 

[Saltyanimals]

CO2 will slowly enter and convert it into calcium carbonate. It might still be usable, if far less potent.

That might have explained why I'm not seeing the potency out of my kalk reactor. The reef chem calculator shows that my alk should be quickly rising given the volume I'm dosing, yet I'm barely able to keep up.

I dug up a 5 year old mostly full BRS kalk from the days where I threw it into an ATO. Visually it looks like kalk in terms of a fine dry powdery material, but I can't tell if it's really now calcium carbonate in powder form.

 

[Pickle_soup]

Everything goes bad.

 

[Randy Holmes-Farley Verified Community Expert]

Everything goes bad.

Does it? I can think of many products that will effectively last forever.

 

[Pickle_soup]

Does it? I can think of many products that will effectively last forever.

Really...go ahead, and take your time to do so, if you're that guy.

 

[Randy Holmes-Farley Verified Community Expert]

Really...go ahead, and take your time to do so, if you're that guy.

I’m just trying to keep this forum from misleading any readers with an inaccurate statement.

I’ve actually been asked a number of times about certain additives and whether they go bad. I’ve correctly answered no, so a statement like yours, even if sarcasm or a joke, had the potential to spread false information.

 

[Pickle_soup]

I’m just trying to keep this forum from misleading any readers with an inaccurate statement.

I’ve actually been asked a number of times about certain additives and whether they go bad. I’ve correctly answered no, so a statement like yours, even if sarcasm or a joke, had the potential to spread false information.

I understand that Kalk has a very long shelf life, but once you open it, and moisture gets in, the clock starts to tik.

 

[saltwater4life]

I understand that Kalk has a very long shelf life, but once you open it, and moisture gets in, the clock starts to tik.

I’m going to have to listen to randy he is an expert been around for many years.

 

[Randy Holmes-Farley Verified Community Expert]

I understand that Kalk has a very long shelf life, but once you open it, and moisture gets in, the clock starts to tik.

I certainly agree that both solid and dissolved versions of calcium hydroxide and oxide can go bad.

 

[Saltyanimals]

I still have the fine powdery dry consistency in my container which suggest it stayed dry, but the unknown variable is the CO2 that may have diminished it. It stayed in a closet far away from all the usual sources of CO2, but I can only assume it's the occasional open/close that likely introduced the CO2 over time. It's not "bad" per se because it's still maintaining alk albeit takes more than the calculator measures confirming the potency reduction.

Stuff is cheap enough that I'll replace. I'll report back if the new fresh stuff appears more potent.

 

[Randy Holmes-Farley Verified Community Expert]

It’s easy enough in most settings to just use more, at least when making it batch wise.

 

[Poseidon03]

Best way to check is mix it up and test pH. If pH is around 12 at full mixture, it is still good.

 

[Randy Holmes-Farley Verified Community Expert]

Best way to check is mix it up and test pH. If pH is around 12 at full mixture, it is still good.

PH 12.0 kalkwasser is only 29% potent. pH us a very crude measure of potency due to it being a logarithmic scale.

 

[Saltyanimals]

PH 12.0 kalkwasser is only 29% potent. pH us a very crude measure of potency due to it being a logarithmic scale.

I noticed the same thing when I stuck a calibrated pH probe to my "saturated" kalk a few minutes after a reactor stir cycle. I landed at 11.9 which I had no bearings until Randy's quantitative response there. I'm dosing 29% weak sauce.

This leads to the next question of what a low potency means. Does it mean lower contribution to alk and/or lower pH benefits from the kalk. Or both?

I'm observing a pH peak of 8.1 which is higher than my tank is used to, but far from the 8.2-8.3+ that others are reporting. [my room Co2 is less than 600]

 

[Randy Holmes-Farley Verified Community Expert]

Lower potency means lower alk and calcium addition, and a smaller pH effect.

Best way to use pH since it is often inaccurate at these high values is to measure the pH of a true saturated solution, and then the pH of the test solution and compare them. A difference of 0.3 pH units is about a factor of 2 in potency.