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I'm curious as to what people use to adjust the pH levels in their aquaponics systems?

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My 'pond' is a converted pool of 35000 gallons so it might take several teaspoons.  Do you buy these products separately?  Is there a particular ponics-safe brand?



Jeff S said:

A good way to raise your PH is with Hydrated Lime and Potassium Hydroxide. Very small quantities of each. I just raised PH from 4.1 to 6.8 with about a half teaspoon of each in a 45 gallon aquarium. Fortunately I don't have fish in that system since it was a rapid adjustment. So you can see how little it takes. The reason for using these 2 elements is that they provide excellent nourishment for your plants while buffering the system. Be careful not to get them on you with water because they become a strong acid.

http://www.amazon.com/s/ref=nb_sb_ss_i_1_12?url=search-alias%3Daps&...

I bought the Essential Depot brand. Check out this video too: https://www.youtube.com/watch?v=zP1rUMyklyc&list=PLAPahqrfGZZnt...

Check out all of Bright Agrotech's videos. Real information you can use. I just realized I wasn't clear on the size tank I used as an example. It was 45 gallons so you'll probably want to use a little more LOL.

G Mo said:

My 'pond' is a converted pool of 35000 gallons so it might take several teaspoons.  Do you these products separately?  Is there a particular ponics-safe brand?



Jeff S said:

A good way to raise your PH is with Lime and Potassium Hydroxide. Very small quantities of each. I just raised PH from 4.1 to 6.8 with about a half teaspoon of each in a 45 . Fortunately I don't have fish in that system since it was a rapid adjustment. So you can see how little it takes. The reason for using these 2 elements is that they provide excellent nourishment for your plants while buffering the system. Be careful not to get them on you with water because they become a strong acid.

Hello, 

 I am having PH issues with our system. It was stable at 7.8ish  for a year or so but sudden dropped to 6 over the summer. I have been trialling various things for buffering: seashells, limestone, potassium bicarbonate, but it is still dropping within 24hours of adding a 'pH up' type product.

 I have also tried the lye mentioned above(I also make soap!)

It is stable at 6.2-6.5  ( if you can call that stable!) 

Our system is about 12,000 litres, I have added about 40-50kg of limestone, 4kg of shells and  'some' ashes for the lye in there at the most. Does anyone have a vague kg of limestone:litres of water ratio?! Maybe is should just keep adding limestone.......

My thoughts are that the buildup of fishpoo and other organic matter (leaves, roots etc that I have missed) in the growbeds is causing the acidification. Anyone have any other thoughts?

Thanks for all the great info!

Becs

I us potassium hydroxide and garden lime along with epsom salt as a steady nutrient/pH adjuster. I have a 500 gallon system and some aquarium setups. 1 teaspoon of this mix raises a 40 gallon aquarium from 6.0 to 6.8 pH. The larger system takes about 1/2 cup 1 to 2 times a week. I also have red wigglers in my GBs to bfreak down any solids.

It seems to me that you've already added an incredible amount of limestone but I've never used it.  6.2 - 6.5 is a great PH for plants so maybe you should just monitor it for a while.  What form was the limestone, a powder?  If it was in some larger form, it will slowly break down over time, as will the shells.  See bright agrotech videos on PH adjustment - Nate recommends calcium hydroxide/potassium bicarbonate, 50/50 and that is what I've been using with good results.

Has your top up water changed?  If not, then you are likely correct that it is the normal nitrification process dropping PH.  Fish growing, eating more food, system maturing - it seems normal.

Good luck


Beca Beeby said:

Maybe is should just keep adding limestone.......

My thoughts are that the buildup of fishpoo and other organic matter (leaves, roots etc that I have missed) in the growbeds is causing the acidification. Anyone have any other thoughts?

Thanks for all the great info!

Becs

Hi.

Thanks for the replies. I am concerned for the fishes health:although they seem happy enough ( tilapia). I was under the impression they preferred a higher pH?

It was limestone gravel, so will last a while!

Beca

Copied below is from Start Here/Rules of Thumb on this site.  Your tilapia should be just fine - they are the industrial fish of aquaculture.  Just be careful if it goes much lower, especially if you fall off the scale of the API test kit.  I wouldn't go below 6.0 but some do.  I raise PH twice per week and some big operations adjust daily.  Raising PH is routine in a normal system.  If you prefer it higher, adjust it higher but don't expect it to stay there.

pH

  • Target a pH of about neutral, or 6.8 – 7.0, in your aquaponic system. This is a compromise between the optimal ranges of the fish, the plants, and the bacteria. For fish, this is a pH of around 6.5 to 8.0. For plants, this is a pH of around 5.0 to 7.0 and for bacteria it is a pH of 6.0 to 8.0.


Beca Beeby said:

Hi.

Thanks for the replies. I am concerned for the fishes health:although they seem happy enough ( tilapia). I was under the impression they preferred a higher pH?

It was limestone gravel, so will last a while!

Beca

Based on Nate Story's advice while bicarbonates help to control swings in pH hydroxides allow for measurable adjustments when there is a problem. That's why I use hydroxides so it doesn't take days to see the change. If you haven't watched the Bright Agrotech videos I too highly recommend them.

6.2-6.5 is great for your plants (and shouldn't cause any harm to your fish or bacteria in a year old system). Important plant nutrients become more available in that range. As long as you're not experience any problems, "if it ain't broke, don't fix it" could be the phrase of the day.

In my experience, when you add things like potassium bicarbonate for buffering, there is an initial, more dramatic rise in pH, which then settles out once things are mixed and aerated. I would guess that whatever your pH value is after 24 hours is the true result of the amount of say, potassium bicarbonate, that you put into your system.

That said, before you go and dump a bunch of extra buffering agents in all willy-nilly, I would go ahead and invest a hardy sum of $7 in an KH levels test kit like the one I've linked to so you can get some accurate info with what exactly is going on with your system water when you're adding your buffering agents.

http://www.amazon.com/API-GH-KH-Test-Kit/dp/B003SNCHMA/ref=sr_1_1?i...

Beca Beeby said:

Hello, 

 I am having PH issues with our system. It was stable at 7.8ish  for a year or so but sudden dropped to 6 over the summer. I have been trialling various things for buffering: seashells, limestone, potassium bicarbonate, but it is still dropping within 24hours of adding a 'pH up' type product.

 I have also tried the lye mentioned above(I also make soap!)

It is stable at 6.2-6.5  ( if you can call that stable!) 

Our system is about 12,000 litres, I have added about 40-50kg of limestone, 4kg of shells and  'some' ashes for the lye in there at the most. Does anyone have a vague kg of limestone:litres of water ratio?! Maybe is should just keep adding limestone.......

My thoughts are that the buildup of fishpoo and other organic matter (leaves, roots etc that I have missed) in the growbeds is causing the acidification. Anyone have any other thoughts?

Thanks for all the great info!

Becs

Thanks- I have a KH testerbtoo, its around 3 now. It initially dropped below 4 every day (after I have gotten it up again), and would go right down to 2, even 1. But seems happy at 3 now :/

The ideal pH for an aquaponics system is 6.8 to 7. To maintain this level we need a regular check on it. If there is any unbalancing in pH level then following are some solutions-

  • To raise pH, I recommend using calcium carbonate and potassium carbonate, and either alternating between them or adding equal amounts of each at the same time.

  • To lower pH, I recommend certain acids, such as nitric, muriatic, and phosphoric.

Regards,
Murray Hallam
Consultant in Queensland
https://www.aquaponics.net.au

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