What use alk more than calcium?

[ReefBeta]

I recently found that the calcium is highly elevated, to almost 600. I have been using only kalk for supplement, so alkalinity and calcium are always added with equal amount. What will consume alk faster than calcium? I do have tons of coraline algae grows. Are they use alk more than calcium?

 

[HuduVudu]

Your biological filter.

 

[ReefBeta]

Your biological filter.

How does bio filter use us alkalinity? Like what chemical reactions involved?

 

[Steve Erekson]

How does bio filter use us alkalinity? Like what chemical reactions involved?

(not a chemist, also doing this very simplified without the + and - and whatnot)

2NH4 + 3O2 > 2NO2 + 4H
2NO2 + O2 > 2NO3

The leftover H+ from the first step reduces alkalinity by reacting with Bicarbonate to produce carbonic acid which is pretty unstable and breaks down into CO2 and H2O.

HCO3 + H > H2CO3 > CO2 + H2O

Or I'm completely wrong, always an option.

 

[LegendaryCG]

(not a chemist, also doing this very simplified without the + and - and whatnot)

2NH4 + 3O2 > 2NO2 + 4H
2NO2 + O2 > 2NO3

The leftover H+ from the first step reduces alkalinity by reacting with Bicarbonate to produce carbonic acid which is pretty unstable and breaks down into CO2 and H2O.

HCO3 + H > H2CO3 > CO2 + H2O

Or I'm completely wrong, always an option.

Pretty sure that makes Meth, I've watched Breaking Bad.

 

[Steve Erekson]

Pretty sure that makes Meth, I've watched Breaking Bad.

brb going to go buy some microbacter7 and baking soda

 

[Jeffcb]

(not a chemist, also doing this very simplified without the + and - and whatnot)

2NH4 + 3O2 > 2NO2 + 4H
2NO2 + O2 > 2NO3

The leftover H+ from the first step reduces alkalinity by reacting with Bicarbonate to produce carbonic acid which is pretty unstable and breaks down into CO2 and H2O.

HCO3 + H > H2CO3 > CO2 + H2O

Or I'm completely wrong, always an option.

Looks right

 

[JGT]

(not a chemist, also doing this very simplified without the + and - and whatnot)

2NH4 + 3O2 > 2NO2 + 4H
2NO2 + O2 > 2NO3

The leftover H+ from the first step reduces alkalinity by reacting with Bicarbonate to produce carbonic acid which is pretty unstable and breaks down into CO2 and H2O.

HCO3 + H > H2CO3 > CO2 + H2O

Or I'm completely wrong, always an option.

Brrrr!! Just got chills.. flashback to college chem class.

 

[josephxsxn]

I don't know the chemistry but it seems that when using kalk this is a side effect, that is slowly raising calcium. Check out Randy's comments in the thread below.

How to mitigate rising Ca when dosing Kalk?

Posting this in the SPS forum, too, because that's what I'm targeting. Question is, when dosing Kalk, you typically have Ca increases disproportionate to alkalinity (albeit very slowly) since kalk is not a truly balanced additive. How do successful reefers overcome this? Are water changes...

www.reef2reef.com

 

[stanlalee]

Well the answer to that question is easy (everything at almost a 3:1 ratio) but that doesn't explain why kalk doesn't deliver perfectly balanced results. You can stop dosing it and just dose baking soda/ash until it's back in balance then resume kalk dosing.

 

[King Turkey]

 

[blasterman]

Kalk is balanced.....well....kind of. Balanced in my definition book is the rate at which stony corals and clams uptake calcium and alk and the ratio it needs to be replenished. This isnt always what the bottle says on it.

If I recall the chemistry kalk is a bit lean on calcium in the long run, but it might have something to do with precipitate being left behind. When I use kalk for dosing I always use all of it. Not just what settles at the top of the jug. Kalk has always kept calcium and alk balanced for me *if* its replenishing stony coral growth only.

The OPs situation is the classic tank that doesn't have much stony coral growth but alk is being used by the obvious mechanisms. So, you end up with high calcium.

Alk, crudely put is a carbon building block for your nitrogen cycle, algae and bacteria blooms etc. Two part dosing and kalk only stay balanced if you have a lot of stony corals or clams consuming calcium.

A box of baking soda and the reef calculator will get alk right. Stop dosing calcium and frankly stop bothering to test calcium and magnesium if you don't have a lot of SPS. Water changes should be more than sufficient to replenish those two.

 

[Randy Holmes-Farley Verified Community Expert]

Well the answer to that question is easy (everything at almost a 3:1 ratio) but that doesn't explain why kalk doesn't deliver perfectly balanced results. You can stop dosing it and just dose baking soda/ash until it's back in balance then resume kalk dosing.

The reason that one cannot dose pure calcium hydroxide long term and not get a calcium rise is that corals do not produce pure calcium carbonate.

Coral skeletons and abiotic precipitation of calcium carboante has some small amount of the calcium in the solid replaced by magnesium and an even smaller amount of strontium.

Thus, the consumption in a reef tank might be 18-20 ppm calcium for each 2.8 dKH of alkalinity, while limewater (kalkwasser) provides ~20 ppm calcium per 2.8 dKH.

The exact in tank ratio depends on the organisms using it, especially whether coralline is a big consumer since it incorporates more magnesium.

Rising and falling nitrate and other factors also impact alk and not calcium consumption.