A Community and Forum For Aquaponic Gardeners

Slightly Acid Tanks

I have a couple Koi tanks that are running higher acid readings. Their Ph readings are about 6.8. I do not recall the mix ratio for adding baking soda to gallons of water in order to move the Ph more towards 7.0.

Does anyone recall how much baking soda per gallon of water is recommended?

Thanks, phil

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Replies to This Discussion

Permalink Reply by TCLynx on November 30, 2012 at 6:07pm

Well, for most people doing aquaponics a pH of 6.8 is actually just about perfect. And most people doing Aquaponics would not want to use baking soda (sodium bicarbonate) since it would add more sodium that the plants usually want.

Realizing that you are probably not doing aquaponics but actually aquaculture but I wanted to make the above note for those who might not realize.

Um, I don't actually know the amount of baking soda you should use. And I expect most people here are more likely to know about using Calcium or potassium hydroxides or calcium carbonate or potassium bicarbonate for buffering the pH back up.

Have you thought about hanging a mesh bag with some chicken grit (calcium carbonate) or limestone chips in the water flow to gently/slowly buffer the pH back up?

Permalink Reply by Phil Slaton on November 30, 2012 at 6:13pm

Thanks TC get some grit at Cenex tomorrow.

Permalink Reply by John E Windsor on November 30, 2012 at 7:35pm

Phil, I have been successfully using a 50/50 mix of potassium hydroxide and hydrated lime to control the pH in my system. It took some trial and error, in a 5 gallon bucket, to get the dosing figured out. For my 800 gallon system it only takes 1 tsp of this 50/50 mix to move the pH up 1/10th of a point. I mix it in a glass container with system water and introduce it equally through the drains of my 4 gravel beds. The use of baking soda adds carbonates back into the system and that can be counter productive.

Let Nate explain it to you like it was explained to me: http://www.youtube.com/watch?v=zP1rUMyklyc

Permalink Reply by Phil Slaton on November 30, 2012 at 8:34pm

Thank you John.

ModeratorPermalink Reply by Bob Terrell on November 30, 2012 at 11:25pm

sent you an email phil on the ratios of baking soda to tank size. call me on skype in the am if you want

Permalink Reply by Phil Slaton on December 1, 2012 at 5:32am

Got it and thanks.

Folks, Bob has the best heater design that you have ever seen. I am successfully using it. 2 heaters working in 2000 gallons of water have raised the water temp from 56 to 68 degrees in 6 days. The catfish really love the heaters. They snuggle up to them.

Again, thanks for the baking soda info.

Permalink Reply by Jon Parr on February 25, 2013 at 2:35am

Don't let carbonates scare you, they are essential to the health of the bacteria. You must keep your KH reading above 40 ppm. Before choosing a hydroxide over a carbonate, you should know what your KH reading is. Systems like Nate's that run a low KH are not stable, and daily testing and correction must be done.

John E Windsor said:

Phil, I have been successfully using a 50/50 mix of potassium hydroxide and hydrated lime to control the pH in my system. It took some trial and error, in a 5 gallon bucket, to get the dosing figured out. For my 800 gallon system it only takes 1 tsp of this 50/50 mix to move the pH up 1/10th of a point. I mix it in a glass container with system water and introduce it equally through the drains of my 4 gravel beds. The use of baking soda adds carbonates back into the system and that can be counter productive.

Let Nate explain it to you like it was explained to me: http://www.youtube.com/watch?v=zP1rUMyklyc

Permalink Reply by Jon Parr on February 25, 2013 at 2:42am

Phil, I don't think there can be an accurate table of how much baking soda, or any other base, to add to achieve a particular pH. For instance, 7 pH is a balance of equal acid components to equal base components. So, a gallon of rainwater would be far more affected by a teaspoon of soda than would be my hard well-water of the same pH.
Bob, would you mind posting the chart? I can't imagine what benefit a PM holds over public posting, and the same goes for the heater. Thanks

Permalink Reply by Vlad Jovanovic on February 25, 2013 at 8:53am

Jon's right in that an accurate table that would hold true for all water in all circumstances would be pretty hard to come up with.

I can't speak for Bob, but maybe he chose the PM route so as to avoid his post/chart becoming 'carved in AP Stone' (Example. 12" is the ideal grow bed depth. Thou grow bed shall be not more, nor less than 12" deep" etc...)

A totally generic statement like "6 grams of baking soda should raise your kH by about 4dH" can be made, but how that plays out in terms of pH depends on some of what Jon already alluded to. The easiest remedy for this includes grabbing a (hopefully 6 gram) teaspoon, a 5 gallon bucket of your water, and your pH test kit.

John W. Listen to Jon...if you plan on using hydroxides and are topping up with rain water (or RO water) grab a kH test kit, because you will crash your system regardless of pH. At a kH of 30ppm you can pretty much forget about nitrification taking place. At 35 things are already somewhat severely limited. 40ppm is about the safest low end threshold.

ModeratorPermalink Reply by Bob Terrell on February 25, 2013 at 9:55am

Vlad, you are correct. Jon, I don't feel I am expert enough to post something like that for the general public. There are just some things that DO NOT need to be carved in stone in AP because of the vairables and the fact that it will tend to mess up the minds and hearts of newbies. There are some things people have to, learn on their own, on their own systems for it to work. What I do sometimes, well others just shake their heads in disbelief. I will try different stuff and if it fails, it fails, I just start over. It is no big deal to me because I look at the big picture down the road.

ModeratorPermalink Reply by Bob Terrell on February 25, 2013 at 9:59am

For the heater, look at the vidoes on this site. It is a design that Rob Nash came up with and I just tweaked it for my needs.

http://www.youtube.com/watch?v=_DMiYSoffBA

Jon Parr said:

Phil, I don't think there can be an accurate table of how much baking soda, or any other base, to add to achieve a particular pH. For instance, 7 pH is a balance of equal acid components to equal base components. So, a gallon of rainwater would be far more affected by a teaspoon of soda than would be my hard well-water of the same pH.
Bob, would you mind posting the chart? I can't imagine what benefit a PM holds over public posting, and the same goes for the heater. Thanks

Permalink Reply by Phil Slaton on February 25, 2013 at 12:45pm

Bob's tank heaters are excellent. I have several extras, ready to go into water, if anyone needs one. phil at jobexpousa dot com