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02/02/2017, 07:12 PM
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#1 |
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Registered Member
Join Date: May 2016
Posts: 106
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Alk swing
I had a couple sick coral. Frogspawn and a newer trumpet frag. I was testing alkalinity almost daily to see if I could notice anything. It started at 9.8 so I quit using Kalk in my ATO to try and target 9 or so.
What I have been noticing is that the alkalinity goes up and down. Yesterday it measured 8.7 and today 9.8. I'm not supplementing any Alk currently. What causes these swings? I'm using the red sea pro kit. The frogspawn is happier and extending but the tissue on the trumpet is still receded. Haven't noticed it getting worse. Thanks in advance! |
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02/02/2017, 08:02 PM
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#2 |
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RC Mod
 Join Date: Mar 2002
Location: Mountain View, CA, USA
Posts: 88,616
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Changes like that sound like measurement problems to me. Alkalinity won't rise unless it's added to the water column in some way. Tap water used for topoff and artificial live rock can be stealth sources of alkalinity, as can pH buffers, which all add alkalinity.
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Jonathan Bertoni |
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02/02/2017, 08:06 PM
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#3 | |
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Registered Member
Join Date: May 2016
Posts: 106
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02/02/2017, 10:14 PM
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#4 |
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Registered Member
Join Date: Jan 2017
Posts: 6
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Calcium, magnesium, strontium will increase Alk. Various supplements also contain hidden ca, mg etc which you may be dosing without realising. Chances are this or measurement error. Ph can vary conditional on c02 given a level of Kh. Kh may also fall due to precipitation.
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02/02/2017, 10:48 PM
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#5 |
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RC Mod
Join Date: Mar 2002
Location: Mountain View, CA, USA
Posts: 88,616
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Metals won't cause the alkalinity to rise. Alkalinity in our tanks is mostly carbonate and bicarbonate ions, which contain no metal. I agree that additives might have some alkalinity in them, and alkalinity certainly can fall due to calcium carbonate precipitation.
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Jonathan Bertoni |
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02/03/2017, 12:43 AM
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#6 |
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Registered Member
Join Date: Mar 2015
Location: Brooklyn, USA
Posts: 126
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I suggest you lay off the testing/dosing. Give it 2 or 3 days to settle and test again then dose up to where you wanna be. Wait another 2 or 3 days and do the same.
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Innovative marine nuvo fusion 40 Not all reefers are nerdy. |
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02/03/2017, 06:48 AM
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#7 | |
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Join Date: May 2016
Posts: 106
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02/03/2017, 10:33 AM
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#8 |
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ReefKeeping Mag staff
 
Join Date: Apr 2006
Location: West Seneca NY
Posts: 27,691
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Calcium, magnesium, strontium are metals and do not raise alkalinity. This is alkainity in seawater:
The main chemical species that contribute to alkalinity in seawater (and the reason it is useful to reefkeepers) are bicarbonate and carbonate (equations 1 and 2). The table below (from "Chemical Oceanography" by Frank Millero; 1996) shows the contribution to alkalinity from the major contributors in seawater at pH 8. If you start at higher pH, the relative contribution of bicarbonate will go down relative the others. Chemical Species Relative Contribution To Alkalinity HCO3- (bicarbonate) 89.8 CO3-- (carbonate) 6.7 B(OH)4- (borate) 2.9 SiO(OH)3- (silicate) 0.2 MgOH+ (magnesium monohydroxylate) 0.1 OH- (hydroxide) 0.1 HPO4-- and PO4--- (phosphate) 0.1 Other species can also contribute measurably to alkalinity in seawater in certain situations, such as anoxic regions. These would include NH4+ and HS- . from: http://www.advancedaquarist.com/2002/2/chemistry
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Tom Current Tank Info: Tank of the Month , November 2011 : 600gal integrated system: 3 display tanks (120 g, 90g, 89g),several frag/grow out tanks, macroalgae refugia, cryptic zones. 40+ fish, seahorses, sps,lps,leathers, zoanthidae and non photosynthetic corals. |
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