Why does a tank only neeed alkalinity

[sigel7]

I was under the impression 2 part dosing should be done equally. Why do I only need to dose alkalinity?

[AlanM]

You should dose both if you are doing sodium carbonate or bicarbonate.

 

Unless you're using kalkwasser to boost alkalinity because then you're already dosing both.

[GraffitiSpotCorals]

If parameters are not in line with what they are supposed to be things like that will happen. For example I think the redfield ratio for nitrate and phosphate is 10 to 1 I believe. Someone correct me if I am wrong.

What test kits are you using?

[Origami]

I was under the impression 2 part dosing should be done equally. Why do I only need to dose alkalinity?

You won't, if you've got corals with growing skeletons. Coral skeletons are formed mostly from calcium carbonate. And, as you might expect, that requires both calcium and carbonate ions. So you'll never really see a situation where you have coral growth without that calcium and alkalinity coming from somewhere. Carbonate is just one species of three that make up "carbonate alkalinity." The only time that I can see where you'd dose only alkalinity is when 1) you have no or very little coral or calcium carbonate being deposited in your system and 2) you have a nitrate problem that you're addressing through water changes. This second condition happens from time to time, but is not common. It comes about because the process of reducing nitrate to nitrogen gas actually returns a unit of alkalinity back to to your water. In a tank that is not fully cycled, alkalinity is actually "consumed" faster than normal because it's not gaining the benefit of this alkalinity ion being returned.

 

Keep in mind that normal target levels of alkalinity are less than half (in ppm) of calcium levels. Example: 8 dKH = 143 ppm CaCO3 equivalents. At the same time, balanced calcium for 8 dKH is about 415 ppm. The other thing to be aware of is the rate of consumption for each in the nominal case. Basically, you can expect a drop of 7 ppm of calcium for every dKH of alkalinity consumed when things are running normally. 

[BtmDweller]

When you say equally... Test Test Test. Alk Ca would not be of equals and tons of variables to consider. Also, consider dosing Mg.

 

 

 

 

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[gmerek2]

The salt you are using probably mixes high on calcium and mag. Keeping them in the upper ranges since there isn’t a lot of uptake. I see no problem using an alk doser to keep your alk number steady. And see no problem keeping mag and calcium in upper ranges with water change

Edited June 12, 2018 by gmerek2

[A.ocellaris]

Here's a good reading about the relationship between Ca, Alkalinity, pH, and Magnesium:

http://reefkeeping.com/issues/2006-06/rhf/

[madweazl]

I was under the impression 2 part dosing should be done equally. Why do I only need to dose alkalinity?

 

Consumption at equal rates doesnt imply the levels desired are at a rate you want to maintain. Like others have stated, water changes and the nitrification cycle can impact levels as well. 

 

If parameters are not in line with what they are supposed to be things like that will happen. For example I think the redfield ratio for nitrate and phosphate is 10 to 1 I believe. Someone correct me if I am wrong.

What test kits are you using?

 

16:1 in regard to nitrates/phosphates but I believe it to be completely worthless in regard to reefing. 

[sigel7]

I use reef crystal salt. My calcium is 450 Salinity 35ppt alkalinity 7 nitrates 25 ph 8.2 and magnesium 1400. This is a frag tank and i dose 25 mill a day alkalinity.

 

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[madweazl]

I use reef crystal salt. My calcium is 450 Salinity 35ppt alkalinity 7 nitrates 25 ph 8.2 and magnesium 1400. This is a frag tank and i dose 25 mill a day alkalinity.

 

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Are you using something to reduce the alkalinity of freshly mixed Reef Crystals?

[Sharkey18]

That's a crazy amount of alk if you're not using up calcium. 

[WheresTheReef]

I had to dose lots of alkalinity in a newish (< 1yr) tank until one day the consumption dropped fairly quickly. I suspect it was due to an incomplete nitrogen cycle as Tom stated above.