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Carbon Hardness Testing (1 Viewer)

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aqua-nut

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I've had a long-term problem with my carbon hardness falling to 3-4 dKH despite adding magnesium each week and eliminating Calcium supplements altogether to see if it would help.

So, I was about to do a water change this afternoon and decided, what the heck, check the dKH of the fresh saltwater to see what it was running. It was only 2.5.

I'm using my own RO/DI water and I've tried three different salt mixes to aleviate the problem.

Any thoughts? Should newly made up saltwater have higher levels?
 
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aqua-nut

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Hmmm. Read 18 times and no one has ideas. Have you ever tested your saltwater for dKH before you dumped it into your sump? What was the reading? What should it be?
 
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ShaneV

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Do you test it right after you make it, or do you let it sit overnight?
 
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Hello,

First let's clarify some things. I assume you are using a Hagen Cabonate and Total Hardness kit. These kits are sold for both fresh and saltwater systems. For use in saltwater systems it is better termed alkalinity not hardness.

Alkalinity for a saltwater system should be targeted at 11 dKH or 4.0 meq/L. This is a measure of the ability of the water system to maintain a stable pH (between 8.0 and 8.4) by neutralizing acidic components. When this value gets too low, a buffer should be added to the system.

Magnesium is not an alkalinity adjuster. If your alkalinity is low, you need to add buffer. There are many forms available from store bought pre-mixes to homemade recipes. Store bought additives are almost always made up of sodium carbonate and sodium bicarbonate with some borates added to the mix. I have always used a homemade version that is only sodium carbonate and sodium bicarbonate (no borates added). It works just fine.

As for your make-up water issue, you won't need to worry over your make-up water if you can get your tank water stabilized. Just invest in a good buffer (homemade or not) and don't worry about the make-up water. There are more factors than we need to consider that will impact your make-up water's alkalinity.

Later,
Trey
 
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aqua-nut

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Thanks for all your help! I've been using Corallife salt for 2 years, then switched to Instant Ocean for about 6 months to see if it would help my low alkalinity. Neither worked... I tested my new IO mixed up water, which sat for 24 hours before I did a water change, and it was woefully low on alkalinity at 4.5 dKH.

I had been using liquid buffer, but found it to be ineffective in raising my alkalinity.

So, I switched over to powder superbuffer dKH and that's working to bring it up. But it still falls a lot and I have to keep my eye on it.

Trey: I am adding magnesium to stabilize the alkalinity and calcium levels, not raise the alkalinity...sorry if I didn't explain this in my original post in this thread.

I think I am going to try a completely different salt mix. I've read online that Marine Environment salt mix was rated the highest in a test, but don't know if this is marketing bunk or truth.

Does anyone have an opinion on what salt I should move to that has better dKH readings?

I'm tired of chasing my water chemistry!
 
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Hello Randall,

Do you test for magnesium and the add to offset the deficit? Magnesium tests are inexpensive and easy to read. I would only add magnesium on demand.

As for salt, I have used instant ocean brand for the last three years without any problem with alkalinity. I simply add buffer as required to my tank. This is not more than once every week or two.

Later,
Trey
 
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BrianPlankis

Randall,

My tank uses up alkalinity like you wouldn't believe. I top-off with kalk and my alk still drops about 1.0 dKH per day. So I add about a 1/2 tablespoon of baking soda daily to keep it steady.

My saltwater (Kent) mixes up to between 8 and 10 dKH and I try to keep my tank around 11-12dKH, so I typically add a little baking soda to my WC water as well. If your WC water is mixing up that low, add baking soda to bring it up.

My other values are 440 for Ca and ~1300 for Mg, so I'm not fighting a major imbalance, it is just my tank uses alk faster than Ca.

Brian
 
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aqua-nut

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Trey: I have a magnesium testing kit from Seachem, which just read 1250. I've been adding the bottle dosage once a week for a while now. I'll test again next week before I add any more.

So at least my magnesium levels aren't out of whack!
 
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aqua-nut

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Brian, I must say that I appreciate your candor. I thought I was the only one with cronically low alk!

Can anyone tell me why this is so from a *biological* perspective (as opposed to the answer, "your calcium is way up and this is what brings it down")? Are my tank inhabitants leaching it out of the water by chance?

My calcium is at 300 or so, so it must not be high calcium dragging down the alkalinity.
 
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BrianPlankis

aqua-nut said:
Brian, I must say that I appreciate your candor. I thought I was the only one with cronically low alk!

Can anyone tell me why this is so from a *biological* perspective (as opposed to the answer, "your calcium is way up and this is what brings it down")? Are my tank inhabitants leaching it out of the water by chance?
Click to expand...

Hey no problem :) Sharing how we have and solve problems, rather than not admitting them, is the only way this hobby will go forward.

I think this article will answer your question from the biological side:
http://www.reefkeeping.com/issues/2004-12/rhf/index.php

Coralline algae uses more Mg and Alk, proportionally to Ca. If you have a LOT of coralline it could be one of your consumers.

Personally I wonder, but can't confirm, if my baby snails use a lot of alk in growing their shells?

Brian
 
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CirolanidHunter said:
aqua-nut said:
Brian, I must say that I appreciate your candor. I thought I was the only one with cronically low alk!

Can anyone tell me why this is so from a *biological* perspective (as opposed to the answer, "your calcium is way up and this is what brings it down")? Are my tank inhabitants leaching it out of the water by chance?
Click to expand...

Hey no problem :) Sharing how we have and solve problems, rather than not admitting them, is the only way this hobby will go forward.

I think this article will answer your question from the biological side:
http://www.reefkeeping.com/issues/2004-12/rhf/index.php

Coralline algae uses more Mg and Alk, proportionally to Ca. If you have a LOT of coralline it could be one of your consumers.

Personally I wonder, but can't confirm, if my baby snails use a lot of alk in growing their shells?

Brian
Click to expand...

Funny that you mention this Brian as I have a lot of coralline algae. I am sure that it brings down my already low alk.
 
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AggieBrandon

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That is one reason I try to scrape my coralline algae off the glass etc. I like the clean look of the tank so it is a win win situation for me. I use a calcium reactor and kalkwasser so I really don't have a problem keeping things stable though :)

B
 
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