Crazy kH consumption?

[Randy Holmes-Farley Verified Community Expert]

@Randy Holmes-Farley

Is it possible for a coral "boom" to happen and you absorb a ton of alkalinity and then all of a sudden....it stops?

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Sure. If the corals deplete something else they need, they will slow or stop growing. If something gets into the tank which deters calcification, that can also happen.

That said. the changes may also be in non-biological precipitation of calcium carbonate, which is impacted by many things, including magnesium (slows it), phosphate (slows it), organics (usually slow it), and iron (as from GFO, can accelerate it).

 

[Randy Holmes-Farley Verified Community Expert]

Aside from a water change, magnesium cannot fall appreciably faster than 1/10 the calcium depletion rate, or maybe 0.7 ppm per dKH of alkalinity. Often much less, and typically not more than 2 ppm per day, often much less than 1 ppm per day.

Anything else is almost certainly testing error.

 

[ReefMadScientist]

time to monitor daily. if the tank is indeed that demanding i would look in to a doser.
i generally dont see mag drops like that unless you switched salt, or if the salt you are waterchanging with got damp/unmixed in the box or bucket.

Yeah I do monitor daily and have a doser.

So a damp salt mix can have ill-effects on Magnesium? What about Alkalinity? My bag of salt had clumps in it for some reason after I used it once. Moisture definitely found its way in the bad somehow which is why I hate the large Red Sea bags. Can I still use the salt and just not the clumps or should I just dump the salt and get a new bucket?

Sure. If the corals deplete something else they need, they will slow or stop growing. If something gets into the tank which deters calcification, that can also happen.

That said. the changes may also be in non-biological precipitation of calcium carbonate, which is impacted by many things, including magnesium (slows it), phosphate (slows it), organics (usually slow it), and iron (as from GFO, can accelerate it).

Interesting. GFO can accelerate or decrease my Alkalinity? My issue is with Alkalinity increasing so I do not know if this can be it.

I also used MicroBacter7 two days ago to try to combat some cyano. Any effects you think on alkalinity? I highly doubt it.

Aside from a water change, magnesium cannot fall appreciably faster than 1/10 the calcium depletion rate, or maybe 0.7 ppm per dKH of alkalinity. Often much less, and typically not more than 2 ppm per day, often much less than 1 ppm per day.

Anything else is almost certainly testing error.

Thanks, I will definitely do some more testing today. I just wish I could trust my tank. I have been testing daily and one day I take a day off to enjoy the tank and Alkalinity shoots up. Go figure.

 

[Russ265]

Yeah I do monitor daily and have a doser.

So a damp salt mix can have ill-effects on Magnesium? What about Alkalinity? My bag of salt had clumps in it for some reason after I used it once. Moisture definitely found its way in the bad somehow which is why I hate the large Red Sea bags. Can I still use the salt and just not the clumps or should I just dump the salt and get a new bucket?

yeah i get weird results when i use clumpy, damp rs salt.
i suggest tying the bag off and shaking it so you get uniformity.

when you mix the salt test the mag you are introducing. if it is less than 1200 you may have your answer.

i really think it could be a combination of testing and damp salt

 

[twilliard]

yeah i get weird results when i use clumpy, damp rs salt.
i suggest tying the bag off and shaking it so you get uniformity.

when you mix the salt test the mag you are introducing. if it is less than 1200 you may have your answer.

i really think it could be a combination of testing and damp salt

I had a damp salt and the mag was so low (and cal) I tossed the salt.
I would have to agree with Randy on depletion rates

 

[ReefMadScientist]

Okay thanks guys. I will make a small test sample today on the fresh salt mix.

 

[ReefMadScientist]

yeah i get weird results when i use clumpy, damp rs salt.
i suggest tying the bag off and shaking it so you get uniformity.

when you mix the salt test the mag you are introducing. if it is less than 1200 you may have your answer.

i really think it could be a combination of testing and damp salt

Russ do you think the same effects with damp salt can play a role with alkalinity...but increase rather than decrease?

 

[gcrance]

@ReefMadScientist im having some of the same issues. Mg suprisingly low alk bouncing up and down trying to find that butter zone on the dosing pump. Ca stable as a rock. So im gonna check my salt mix also cuz mine had got wet previously i never knew it would jack up the values. After all i add it to water ya know?
@Randy Holmes-Farley in another thread we talked about re checking the calibration of my refratometer. Checked and was spot on. But maybe you should check yours too @ReefMadScientist just to rule it out.

 

[ReefMadScientist]

@ReefMadScientist im having some of the same issues. Mg suprisingly low alk bouncing up and down trying to find that butter zone on the dosing pump. Ca stable as a rock. So im gonna check my salt mix also cuz mine had got wet previously i never knew it would jack up the values. After all i add it to water ya know?
@ReefMadScientist[/USER] just to rule it out.

Yep. I am making a test batch right now.

 

[gcrance]

Lemme know how that goes. Im hoping i can get my truck loaded soon so i can get home today to play with my tank a bit. Got a fresh 35g of rodi waiting on me to get home a use it

 

[Randy Holmes-Farley Verified Community Expert]

FWIW, if the alkalinity in a salt mix (regular, damp, hardened, whatever) is normal, the calcium and magnesium will be normal because the only way for it to get depleted is to precipitate as calcium/magnesium carbonate.

Also, even if every bit of alkalinity got used up, it won't deplete them all that much.

For example, start at 1350 ppm magnesium and 11 dKH alkalinity. If you drop that alkalinity all the way to zero with magnesium carbonate precipitation, magnesium can only drop to 1253 ppm. That won't ever happen, but it puts an absolute upper limit on how much magnesium could drop.

More commonly in a hardened salt mix that had been damp, you loose up to a few dKH of alkalinity, maybe 10-30 ppm of calcium, and a few ppm of magnesium.

 

[ReefMadScientist]

Update:

I checked my salt and it seems to be fine.

The Calcium and Alkalinity was a little lower than suggested on the bag but Magnesium was dead on.

1.026:
Alkalinity 11.46
Calcium: 425
Magnesium 1350

@Randy Holmes-Farley just to make sure I was reading your research correctly, GFO can increase Alkalinity?

Its either GFO or error of testing on the Magnesium but will do that again shortly.

As for my Alkalinity, not sure what caused that to spike.

 

[Randy Holmes-Farley Verified Community Expert]

@Randy Holmes-Farley just to make sure I was reading your research correctly, GFO can increase Alkalinity?

Its either GFO or error of testing on the Magnesium but will do that again shortly.

As for my Alkalinity, not sure what caused that to spike.

No, GFO does not increase alkalinity.

It increases the precipitation of calcium carbonate on it and just downstream of it, increasing demand for calcium and alkalinity.

Reducing phosphate can also result in increased calcification by some corals, at least if phosphate started high to begin with.

 

[ReefMadScientist]

No, GFO does not increase alkalinity.

It increases the precipitation of calcium carbonate on it and just downstream of it, increasing demand for calcium and alkalinity.

Reducing phosphate can also result in increased calcification by some corals, at least if phosphate started high to begin with.

Hmm ok. I am starting to believe my corals just took a break from growing all of a sudden. My tank was sucking alkalinity at 62ml like a champ and then all of a sudden it stopped. Very strange.