Tennsquire
Well-Known Member
Can scraping the coralline off the sides of the tank cause alk to jump? I cleaned up the glass today and saw a jump in alk, which is fairly stable due to auto dosing 2x a day. No other variables.
Alk and Coralline Algae
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XNavyDiver
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Well, as no one has took a stab at this one, I'm gonna say unlikely. I've just never heard of such a scenario before.
chipmunkofdoom2
Always Making Something
Some anecdotal evidence from Jim Welsh suggests this is possible. Check out his demonstration video from MACNA. Start watching around 15:51. He mentions that after scraping off a bunch of coralline algae, he observed carbonate alkalinity beginning to rise.
The degree to which your alkaliniy "jumps" as you describe it would depend upon the amount of coralline algae you have as well as the other calcifying organisms in the tank. But logically and from Jim's experience, it doesn't seem too farfetched.
haanstang
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So maybe not scrap it all in one day. That's good to know for a sps tank
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Tennsquire
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Thanks for the info. I know it takes up alkalinity, and wondered where that "goes" when the algae is broken up. I don't know if it dissolves, or falls to the substrate, or what. I did see a healthy jump in alk over a time when all I did was scrape coralline....
haanstang
Well-Known Member
How much did it go up? What size system do you have? And how much "ballpark"did you scrap off. I'm only asking incase it's a high enough jump to worry about in a large system.
Thanks
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Tennsquire
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8.1 to 8.8 (Hannah checker; Salifert read 8.9). 75 gallon with 20 gallon sump and 5 gallon fuge; maybe 85 gallons of water total. I typically clean the glass weekly but let it go a couple if weeks. A good bit of coralline, but not solid sheets of it. It's back down to 8.3 tonight. I want to say user error was to blame, but both kits showed an increase....
Randy Holmes-Farley
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Coralline algae takes up alkalinity and deposits it as calcium carbonate.
Scraping it off the glass DOES NOT release any alkalinity back to the water. It stays in the solid form like sand grains or a coral skeleton.
As noted above, if you got a particle of coralline into the alk test, it will falsely read as a boost to alkalinity because the calcium carbonate in it will dissolve in the low pH of an alk test.
I'm not sure exactly what Jim showed, but in his aquarium he is constantly dosing alkalinity. If you scrape coralline and demand for it thus goes down, he'd perhaps see a rise in alkalinity because the scraped coralline may reduce its uptake of additional alkalinity.
Scraping it off the glass DOES NOT release any alkalinity back to the water. It stays in the solid form like sand grains or a coral skeleton.
As noted above, if you got a particle of coralline into the alk test, it will falsely read as a boost to alkalinity because the calcium carbonate in it will dissolve in the low pH of an alk test.
I'm not sure exactly what Jim showed, but in his aquarium he is constantly dosing alkalinity. If you scrape coralline and demand for it thus goes down, he'd perhaps see a rise in alkalinity because the scraped coralline may reduce its uptake of additional alkalinity.
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Tennsquire
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Thanks, Randy. I imagine that I did indeed get some particles in the water that I tested, which threw off the test.
Amoo
Professional Thread Derailer
Mind blown by again something so very simple and common sense like.
