Alkalinity levels/testing

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Alkalinity levels/testing

Postby Mike Brolin on Sat Jan 31, 2015 5:35 pm

Got a Hanna Alk tester. Test show 94 PPM CaCO and using .056 conversion rate I came 5.246 dkH.
This seems lower from what i've read it should be in the 8-9 range dkH
\ Anyone have experience with hanna Alk testers?
Other info on Alk level/testing.
I'm using reef crystals salt
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Re: Alkalinity levels/testing

Postby starboard on Sat Jan 31, 2015 5:47 pm

That's pretty low. I would do a full water change and then test again. If it is still low then you may want to dose to get your levels up.
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Re: Alkalinity levels/testing

Postby Mike Brolin on Sat Jan 31, 2015 7:51 pm

Ok I've retested twice and got 6.6 and 6.5.
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Re: Alkalinity levels/testing

Postby Socratic Monologue on Sat Jan 31, 2015 10:05 pm

The Hannah alk checker is known to read about 1 dKh high. I've not read that it is inconsistent, though, so your first result might have just been a fluke. At any rate, I'd check it against a reliable kit like Lamotte (or even API, which IME tests the same as Lamotte).

FWIW, I have the Phos Checker and really like it.
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Re: Alkalinity levels/testing

Postby MadCityReefer on Sun Feb 01, 2015 7:27 am

I've tested my Hanna Alk checker against my Salifert twice and it was spot on. The Hanna phosphate is also really good but the Hanna Calcium checker sucks!
KEEP ON REEFIN ON!!
tank build: viewtopic.php?f=2&t=12927
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Re: Alkalinity levels/testing

Postby Mike Brolin on Sun Feb 01, 2015 7:56 am

What do people feel is the optimum Alk level? and What do you use to raise? I just tested the water to be used for water change(reef Crystal) and got a reading of 6,5
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Re: Alkalinity levels/testing

Postby Socratic Monologue on Sun Feb 01, 2015 11:01 am

Mike Brolin wrote:What do people feel is the optimum Alk level? and What do you use to raise? I just tested the water to be used for water change(reef Crystal) and got a reading of 6,5


I keep 9-12 dKh. Folks that run ULNS seem to prefer lower levels, I think. I use baked baking soda to maintain (I dissolve it in ATO water).
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Re: Alkalinity levels/testing

Postby adadwa on Sun Feb 01, 2015 10:20 pm

6.5 seems awfully low for a fresh batch of Reef Crystals. Did you test immediately after mixing? You should allow the salt to mix for at least 2-3 hours prior to testing. It can take quite a while for it to stabilize, especially the alkalinity. A fresh batch of Reef Crystals should have an alkalinity of 12-13 dKH. Natural sea water has an alkalinity of 7. Most people run in the 9-12 range. I prefer 9. The biggest thing is to keep it stable, especially if you have SPS. You can use baked baking soda to raise your alkalinity. Just bake some baking soda (not baking powder) in the oven at 250-300 for at least 30 minutes to make soda ash. I recommend using a glass pan to minimize the chance of contamination. There are several reef calculators online to tell you how much to add. You might also want to pick up an API alkalinity test kit to double check your results. They are cheap and will give you a reasonable comparison.
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Re: Alkalinity levels/testing

Postby BraenDead on Mon Feb 02, 2015 4:21 pm

I've used a couple Hanna checkers before, and they work well and were consistent with my Salifert test kit results. They can be sensitive to any imperfections on the glass (small scratches, not perfectly clean, etc). It's important to treat the glass delicately, and the vials are not cheap to replace (it's not normal glass). Make sure to use the same glass vial during your test.

I would recommend comparing it to another test kit that you trust. Just basing it off the salt isn't always a good idea, unless the salt has a known alkalinity level (there can always be some buckets that vary).

adadwa wrote:A fresh batch of Reef Crystals should have an alkalinity of 12-13 dKH.

I believe that Reef Crystals changed their salt in late 2014 and newer batches have lower alkalinity levels. I always recommend people test each new bucket of salt, however, to compare with their prior bucket of salt.

The general recommendation for alkalinity is 7 to 11 dKH (the ocean is typically ~7dKH), but it can depend on what level your tank pH is at (a tank with higher pH should run alkalinity on the lower side of the recommended range). Also ultra low nutrient systems can reportedly have some issues with higher alkalinity as well.

adadwa wrote:The biggest thing is to keep it stable, especially if you have SPS.


This is key - stability really helps many corals. Alkalinity changes much faster than calcium or magnesium (6x faster than calcium in a reef tank) and should be checked much more often than alkalinity.

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