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Thanks for the informative post

Thanks to Rk Castillo and Vlad Jovanovic for talking about low kH consentrations inhibiting cycling from getting started. I had been feeling discouraged after several weeks of just seeing lite blue nitrite test results. After useing powdered Potassium Carbonate to bring the kH up, I finnaly started seeing the nitrites. As the book said, the pH drops a bit as the bacteria eat up the Ammonia, but how long should I keep the kH up by adding the potassium carbonate? After adding potassium carbonate to get the kH up, my pH is now around 8.2. Did the bacteria just need the extra kH to get them started and then need it less once they are established? When should I let the pH slowly decend back to around pH7. Or is there something else I should do to help the bacteria, now that they are finnaly here? Thank you in advance for the help.

Robert

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Permalink Reply by Alex Veidel on April 12, 2013 at 4:56pm

Hey, I've got a discussion called "Give a Shout Out!" that I was hoping would be a collaborative collection of appreciation. You're welcome to post your thanks there if you're interested. But you know, whatever :)

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Permalink Reply by Vlad Jovanovic on April 13, 2013 at 3:52am

Hi Robert. Glad that cycling has perked up. The question you pose is a very interesting one. kH, like pH is probably much more important for bacteria during cycling...as opposed to after they have become firmly established. Conventional wisdom coming from RAS and waste water treatment studies says that nitrification is greatly inhibited at a kH below 40ppm regardless of pH. BUT, I'm not so sure that that number holds true in an AP setting. I suspect that it can be 'much' lower in an established system. It does seem that nitrifiers need a certain amount of inorganic carbon food source (which bi-carbonates/carbonates provide)...But what that exact number is, is not going to be something that anybody knows...

Also, potassium carbonate (KCO3) is twice as ‘strong’ as potassium bicarbonate (KHCO3)…(yeah, I know…it might seem counter intuitive at first, but trust me)…So just make sure the amount of KCO3 your adding per gallon aren't the amounts that anyone stated for KHCO3 :)

Not much else you can do for the bacteria other than to keep the pH a bit high (like you have it...say 7.6 to 8.2) and keep them fed with both an adequate amount of ammonia (1 to 4ppm) and and adequate amount of carbonate hardness (for now, we'll say around 40ppm)...

Here some more kH stuff if you're interested...

http://community.theaquaponicsource.com/forum/topics/my-ph-is-low-w...

http://community.theaquaponicsource.com/forum/topics/kalkwater-in-a...

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Permalink Reply by Robert Wright on April 13, 2013 at 10:46am

Thank you Vlad, your help is much appreciated.

Vlad Jovanovic said:

Hi Robert. Glad that cycling has perked up. The question you pose is a very interesting one. kH, like pH is probably much more important for bacteria during cycling...as opposed to after they have become firmly established. Conventional wisdom coming from RAS and waste water treatment studies says that nitrification is greatly inhibited at a kH below 40ppm regardless of pH. BUT, I'm not so sure that that number holds true in an AP setting. I suspect that it can be 'much' lower in an established system. It does seem that nitrifiers need a certain amount of inorganic carbon food source (which bi-carbonates/carbonates provide)...But what that exact number is, is not going to be something that anybody knows...

Also, potassium carbonate (KCO3) is twice as ‘strong’ as potassium bicarbonate (KHCO3)…(yeah, I know…it might seem counter intuitive at first, but trust me)…So just make sure the amount of KCO3 your adding per gallon aren't the amounts that anyone stated for KHCO3

Not much else you can do for the bacteria other than to keep the pH a bit high (like you have it...say 7.6 to 8.2) and keep them fed with both an adequate amount of ammonia (1 to 4ppm) and and adequate amount of carbonate hardness (for now, we'll say around 40ppm)...

Here some more kH stuff if you're interested...

http://community.theaquaponicsource.com/forum/topics/my-ph-is-low-w...

http://community.theaquaponicsource.com/forum/topics/kalkwater-in-a...