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Low pH and Alkalinity.

This is a discussion on Low pH and Alkalinity. within the Water Chemistry forums, part of the Advanced Saltwater Discussion category; --> What salt mix are you using? Does it have Borate and magnesium concentration percentages anywhere on the label? Reduction-Oxidation can be accelerated by light ...

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Low pH and Alkalinity.
Old 08-10-2009, 12:24 PM   #11
 
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What salt mix are you using? Does it have Borate and magnesium concentration percentages anywhere on the label?

Reduction-Oxidation can be accelerated by light and heat. Can you test Mag?

Last edited by wake49; 08-10-2009 at 12:30 PM..
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Old 08-10-2009, 12:47 PM   #12
 
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I'm using Red Sea Salt mix but there's no labels that mention what it has in it. And unfortunatly until I get some cash I'm unable to test mag. since I don't have a test for it.
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Old 08-10-2009, 01:19 PM   #13
 
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What kind of water are you using?
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Old 08-10-2009, 01:25 PM   #14
 
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Tap unfortunatly because the only store that sold RO doesn't do it any more. And cince I live in apartments I can't get a unit either. But I havn't used RO in almost a year. Not that it's a good thing but I don't think it would suddenly change like that. By the by, my pH is back to 8.2 thanks to the buffer (assumingly).
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Old 08-10-2009, 01:43 PM   #15
 
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How many times did you test it when you came up with the 7.8 reading? And what time of the day were you testing it? Do you condition the tap water at all?
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Old 08-10-2009, 03:04 PM   #16
 
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I only checked once and the time of day was probably around 5-6PM. I use Prime and Stability when I use tap.
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Old 08-10-2009, 03:08 PM   #17
 
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It might have been a bad test, maybe a drop didn't come out? Or maybe a bad sample?

What is your alk reading now?
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Old 08-10-2009, 05:19 PM   #18
 
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I am just reading this thread and nodding my head up and down. I have nothing to add. The line of questioning here is right on course.

Ok, maybe I have something to add. Even if the temperature has been high for an extended period, the addition of Calcium chloride could have increased calcium levels to cause a precipitation, especially given that calcium precipitates more readily at higher temperatures. (Wake - this is new to me. I believe you, but do you have a link? Knowledge is power!)

However, if you did in fact precipitate calcium, I believe it would have been visible. I have seen this occur in person, and it is very difficult to mistake for anything else. It literally looks like it is snowing inside the aquarium, unless of course it is just a small isolated precipitate on the heater.

Also, by testing pH in the evening, you are getting a higher reading than you would have received in the morning. This worries me, because your pH had a low point of below 7.8. I'm glad you caught this and are dosing accordingly.

Great questions on borate and magnesium. Some research is needed on this (google?), because if these concentrations are higher than the natural ratios in seawater, then the alkalinity test kit will give you a false low reading, with the result based on the assumption that magnesium, borate, and calcium are in balance, and the test actually testing for calcium buffering ions. So, if Calcium is 440 ppm and the other levels are unnaturally high, then calcium is more likely to precipitate, causing the rapid pH drop. Fun stuff. Ironically, many sea salts add additional borate and magnesium for additional buffering capacity, on the assumption that the fishkeeper will not test for alkalinity as they should. The additional buffering helps between water changes.
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Old 08-10-2009, 05:45 PM   #19
 
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I read it in a Randy Holmes-Farley article. It's about three quarters of the way down. It kinda makes sense to me as redox is accelerated by both light and heat. I would then consider that calcium and carbonate would go through a reduction as the temp rises, and bicarbonate would become predominate. Of course the swing in pH that Hardcory experienced would probably have been caused by either a large temp jump, or a prolonged temperature change.

This hobby makes me think that I probably should've majored in Chemistry instead of Biology.
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Old 08-10-2009, 06:06 PM   #20
 
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Farly is the best. I have several of his articles saved in my favorite links. Alkalinity is such a complicated subject it is no wonder that the LFS generally just skip the entire discussion. I find myself not worrying about the why and instead just focusing on the what to do.
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