Should I dose Kalk via ATO to raise alkalinty?

[donnievaz]

My parameters have been pretty steady with what I think is low dkh. 

 

As of last night. All API tests except magnesium which is Salifert.

 

Salinity - 1.026 I use an ATO and this stays pretty much rock solid. 

PH - 8.3-8.4 (hard to read the color scale accurately)

Alk - 7 dkh

Calcium - 480

Magnesium -1200

 

Nitrate - 0

Phosphate - 0

I don't really believe these 2 to be true but I figure if it's undetectable it's not a problem...

 

I'm using Brightwell NeoMarine salt mix. I do a 4.5 gallon water change once a week on a 29 gallon BioCube. 

 

Would dosing Kalk in the ATO water raise my Alk without throwing anything else out of whack?

 

 

 

[arking_mark]

Kalk raises ph and calcium as well... Ph impact minimal with just top-off water on a hooded system.

[donnievaz]

Kalk raises ph and calcium as well... Ph impact minimal with just top-off water on a hooded system.

 

Any suggestions on the best (easiest, most stable) way to raise alk only or would I be better off leaving it alone? 

[thakki]

Easiest way is to dose Sodium bicarbonate (baking soda)...it will raise the alkalinity while lowering the pH..since your pH is in the high range...you will be fine.

[Origami]

Use a reef chemistry calculator like this one to help you figure out how much baking soda (or other additive) to use.

[donnievaz]

Use a reef chemistry calculator like this one to help you figure out how much baking soda (or other additive) to use.

 

What's a good number to shoot for considering my other stats? I'm thinking 9 dkh. 

[Origami]

Anywhere from 8-10 dKH is typical for most of us. 9 dKH is right in the middle.

[donnievaz]

Thanks, I'll give it a shot. 

[mr11]

From what I understand Kalk is used more to keep parameters stable. As others have mentioned other products are better for raising parameters to the desired range. 

[Origami]

From what I understand Kalk is used more to keep parameters stable. As others have mentioned other products are better for raising parameters to the desired range. 

Not quite. The typical method of dosing kalk (through a Kalk stirrer and ATO, for example) adds stability because the dosing follows evaporation. You can get similar stability by dosing two-part using peristaltic pumps (turning them on multiple times per day).

 

Fundamentally, you need to understand what kalkwasser is. Kalkwasser is a saturated solution of calcium hydroxide, Ca(OH)2, or hydrated lime. Calcium hydroxide has low solubility in fresh water, so it saturates quickly (about a teaspoon per gallon), and the somewhat milkly fluid, once all the solids have settled out, is called kalkwasser. When calcium hydroxide is added to fresh water, it dissociates into a calcium ion and two hydroxide ions. The hydroxide ions, in turn, combine with dissolved carbon dioxide in the water to form two bicarbonate ions. That is, Ca(OH)2 + 2(CO2) ==> Ca++ + 2(OH-)  ==> Ca++ + 2(HCO3-). This happens to be the exact ratio that is needed when calcium carbonate (CaCO3), which is the primary component of coral skeletons) is formed. This is why kalkwasser is called a "balanced additive:" It adds calcium and bicarbonate alkalinity in the proportions typically needed by organisms to lay down calcium carbonate material. Since it is "balanced" you don't need to meter out two different solutions - it's balanced naturally. However, kalk has its risks, too. (Different discussion.)

 

Because kalk is used to deliver both cacium and alkalinity, and because the OP's tank is already biased high on the calcium side, kalk is not a solution for that situation. 

 

Once alk is balanced, the OP can go about determining the best dosing strategy (which can be kalkwasser, two-part, manual dosing, metered dosing, etc.).

[donnievaz]

A1/2 teaspoon of baking soda and glass of RODI later and I'm up to 8 dkh. I'll do it again tomorrow to go to 9 and I'm good to go. Thanks for the help. I guess I'll just keep an eye on it and go from there.

[Origami]

A1/2 teaspoon of baking soda and glass of RODI later and I'm up to 8 dkh. I'll do it again tomorrow to go to 9 and I'm good to go. Thanks for the help. I guess I'll just keep an eye on it and go from there.

It's nice to find something inexpensive and effective in this hobby, isn't it?

[WheresTheReef]

It is probably worth noting that you don't want to raise the alkalinity in large amounts with certain livestock such as sensitive sps. 1dkh should be safe, but I wouldn't push it too fast.

[donnievaz]

It's nice to find something inexpensive and effective in this hobby, isn't it?

 

Definitely! Not to mention the fact that all I had to do was go to the pantry a grab a box...

[donnievaz]

It is probably worth noting that you don't want to raise the alkalinity in large amounts with certain livestock such as sensitive sps. 1dkh should be safe, but I wouldn't push it too fast.

I read that 1.5 dkh per day was about the max which seems a little drastic when it's so easy to just bump it up slowly. 

[s2nhle]

I am dosing alk with my dosing pump several times at night.

[Origami]

I read that 1.5 dkh per day was about the max which seems a little drastic when it's so easy to just bump it up slowly. 

1 dKH per day is roughly 0.35 meq/day. It's plenty slow. If concerned, you can drip it in or bump it up in stages over several hours.

 

A mature tank with a lot of SPS can drop a couple of dKH or more in a day simply due to normal consumption.

[donnievaz]

1 dKH per day is roughly 0.35 meq/day. It's plenty slow. If concerned, you can drip it in or bump it up in stages over several hours.

 

A mature tank with a lot of SPS can drop a couple of dKH or more in a day simply due to normal consumption.

 

Good to know. Is it safe to assume that once the alk is up that the available calcium will be more easily consumed and both should be dropping to some extent over time? 

[Origami]

Good to know. Is it safe to assume that once the alk is up that the available calcium will be more easily consumed and both should be dropping to some extent over time? 

Under normal circumstances, calcium and alkalinity consumption balance reasonably closely. That ratio of 2.8 dKH of alkalinity consumption for every 20 ppt of calcium varies only very slightly as some corals will substitute a magnesium ion for a calcium ion in a very small bit of their skeleton. There are other situations where the balanced uptake can vary, but they're uncommon in a stable tank. One such situation occurs, for example, in a tank that has not completed cycling and has a nitrate level that is increasing. 

 

Randy Holmes Farley did an article on this a number of years ago to help answer the question of what's going on when calcium and alkalinity demand don't fit the perfect ratio. That article is here.

[donnievaz]

 

Randy Holmes Farley did an article on this a number of years ago to help answer the question of what's going on when calcium and alkalinity demand don't fit the perfect ratio. That article is here.

 

Thanks