My dKH is at 20.4?!

[ejmeier]

I just got my salifert calcium and alk test kits. But I found something quite strange, and at first I didn't believe it, but now I guess it must be true.

Here's how my testing procedure went:

Let's see - temperature... 80 F, check.
Sg..... 1.025, check.
Calcium.... 410 ppm, check.
pH (morning).... 8.1, check.
dKH.... 20.4, what the?!?!

How could my alk be this high? I didn't even think this was possible. The Salifert tests only go to 16 dKH, and the full syringe didn't give me a color change. But the second option to use half solution and double the results gave me a dKH of 20.4

I thought (hoped) I had a defective test kit or I was doing something wrong, but I tested out my other reef tank, and it tested at 12 dKH (probably a bit lower than this as I was adding the drops pretty fast.)

The tank is new and has only been set up for about a week and a half. Is this normal? I know there are a lot of factors that could be causing this, if you need more info on my system, just ask as I wasn't sure what was relevant.

 

[Randy Holmes-Farley]

It is theoretically possible, yes. It is also possible that the organic levels in a new tank like yours are high enough that they impact alkalinity. So it may be nothing to especially worry about for now.

Are you supplementing calcium and alkalinity, and if so, how?

 

[ejmeier]

The tank is so new that I have been doing hand top offs with kalk. I just hooked up my float switches and kalk reservoir, so all evap will be replaced with kalk.

There are a few SPS frags, very small, that's about it in terms of calcium demand that I can think of.

What exactly do you mean by high organic levels? I used LR from an existing tank, so there was no die-off or anything like that. Also, there are no fish in the tank, but I did add a very small bit of food for the hermit crabs and other scavengers.

FWIW, I just retested the calcium, this time with the "high resolution mode" and was a bit more careful than last time. It came out as 455 ppm.

Is the alk anything to worry about, will it injure or stress any livestock that I put in the tank?

Thanks for the help.

 

[Randy Holmes-Farley]

If the alkalinity is truly all (or mostly all) carbonate alkalinity, then the only risk that I know of at 20 dKH is that maintaining adequate calcium is more difficult. That appears to not be a problem for you (yet).

The organics possibility in new tanks was recently mentioned by Habib (owner of Salifert):

http://reefcentral.com/forums/showthread.php?s=&threadid=230740

An alternative explanation is that if you start with something like Instant Ocean at 350 ppm calcium and 7 dKH alkalinity, and use limewater to raise the calcium and alkalinity with limewater (or any balanced two part additive) this is what you will get:

calcium alkalinity
350 ppm 7 dKH
370 ppm 9.8 dKH
390 ppm 12.6 dKH
410 ppm 15.4 dKH
430 ppm 18.2 dKH
450 ppm 21 dKH

If that is it, then I'd let the alkalinity drop back a bit by using some clacium chloride instead of limewater for a few days.

Such a correction is described in this article:

Solving Calcium and Alkalinity Problems
http://www.advancedaquarist.com/issues/nov2002/chem.htm

 

[ejmeier]

I used CS Bio-assay exclusively for my salt in this tank. Not sure what it mixes up at...

Same effect there.

But now I think that I'll start out with just the calcium part of the supplement and monitor both Ca and alk closely until there is a balance between the two.

:thumbsup:

 

[Randy Holmes-Farley]

Oh oh, I abused my power. I should never be trusted with editing power. :lol:

Anyway, I hope you understand my response above that I mistakenly wrote over you last post.:worried2:

 

[ejmeier]

Just an update, and also a question.

I have begun to correct my imbalance in my aquarium, and the tank is at about Ca 400 and dKH 15. It isn't there yet, but it's a step in the right direction.

I just tested my tapwater though, and it was at 19.6! Could this be right? It was basically tested right out of the tap. I never got a full color change, rather the bluish color turned clear, but it never turned the final color. I interpreted the change from blue to clear to be the end of the test.

Anyway, is it okay to use this test on FW? 19.6 dKH is sky-high, but when you consider that we don't have a water softener, is this reading still out of line?

 

[Habib]

Anyway, is it okay to use this test on FW?

Yes you can use it with any fresh or saltwater.

The 19.6 dKH is very high. I don't know your water report. If you have it then cheking the value might be good.

 

[ejmeier]

Also, if my tapwater is actually close to 20 dKH, would this have a negative impact on the quality of kalk that I dose to the tank?

 

[Habib]

IMO , neglecting any bad things in tapwater, the alk if actually 20 dKH (7 meq/L) will be enough to cause 140 ppm calcium to precipitate from the limewater. Saturated limewater will contain approx. 800 ppm of calcium so you might to have add about 30% more lime to the water compared to RO water users to get a saturated solution.

You might also have a bit more fines in the water but most might settle before use.

 

[Randy Holmes-Farley]

I agree. I would not generally use tap water to dose limewater in any case, including yours where the alkalinity is that high. You will precipitate calcium carbonate, leaving the water rich in alkalinity relative to calcium. In a sense, it is no longer a balanced additive.

 

[airinhere]

Great info here. Just wanted to make it available during the daytime when I cant use the search function.

 

[Randy Holmes-Farley]

No need to bump threads. You can subscribe to be alerted to new posts by email, and if you have your settings such that all posts are shown, they are all ways there, just by scrolling down.