Aquaponic Gardening

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I have had my aquaponic system up and running for about two months. I regularly test the water. My pH has been at least 8.8 (max value of my test kit). My beds are half lava rock and half grow stones. I have 5 small koi, running ~ 175-200 in my tank with two grow beds. My water supply is pH neutral. Any suggestions?

Thanks!

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You can add more fish.
When they breath the amount of CO2 increase so even the carbonic acid. This way the ph will tend to decrease by the time.
This happen because your water olds carbonates. If you can see white powder on your media this is the sign your gh and kh values are too hight.
I suggest to change progressively the water with new one. This way you will have less basic substances dissolved into your water.
You can also use nitric or phosphoric acid to decrease the ph value, but you can kill your fishes if you over dose the quantity. I lost a beautiful golden koi in this way... damn it!
So this is my recipe:
1. Change the entire amount of water of your system. Progressively indeed.
2. Add more fishes till of about 1 kg every 50 lt of water.
This is the way I solved my hight ph isses, using fishes instead of chemucal compounds.
I hope you will find useful my advices.
Happy aquaponics :)

As previously mentioned your water supply is likely contributing to the problem though you say it tests neutral.  Testing the water supply directly from the source often gives bad results.  I let mine sit in a tank to allow the chlorine to dissipate and behold watch the PH shoot over 8.  As my system got closer and closer to being cycled I saw the PH drop.  I am not quite there yet and I was allowing the PH to run high to help cycle the system.  I am running fishless at the moment.  Now if I keep my hands off of the chemicals it will settle out at 6.8.  I too have Lava rock and clay grow media.  So I try to top off with only small amount from my water supply and pray for rain.  When we get a drought I have to put my settling tank in the back of my pickup and drive to the creek.  Man I hate to haul those buckets of water up the hill but it is really good water.

Hi Tradewind. Your right, it's always a good idea to let your tap water sit out in a glass for a couple of days before testing the pH. But it's not the chlorine off-gassing that causes the phenomena you described. My water behaves the same way, and it comes directly from a well/aquifer with absolutely no chlorine or chloromine added.

It is the CO2 that needs to off-gas before you can get a reliable pH reading. See CO2 is soluble in water only under pressure (like in your pipes). When CO2 i dissolved in water it is called cabonic acid (H2CO3) and since it is an acid (albeit a weak one) it will affect your pH reading if you test directly from the tap. Like you say, letting the water sit out for a few days will take care of this 'false low' pH reading... Anywho's...

Roger...pH 8.8 is really quite high. You need yo figure out what is going on there. Lava rocks sold for landscaping purposes in the US, usually first do a tour of duty as part of an industrial or wastewater treatment filtration scheme before being sold off to Home Depot or the local landscaping company or whatever. So they can be kind of a crap shoot. Also, depending on where in the earth's crust they were formed their chemical composition (which may affect their pH) can vary wildly. I'm not saying it's your lava rocks that are causing the problem, but it might be wise to check them out when going about figuring out the root of your pH woes...Good luck 

Tradewind said:

As previously mentioned your water supply is likely contributing to the problem though you say it tests neutral.  Testing the water supply directly from the source often gives bad results.  I let mine sit in a tank to allow the chlorine to dissipate and behold watch the PH shoot over 8.  As my system got closer and closer to being cycled I saw the PH drop.  I am not quite there yet and I was allowing the PH to run high to help cycle the system.  I am running fishless at the moment.  Now if I keep my hands off of the chemicals it will settle out at 6.8.  I too have Lava rock and clay grow media.  So I try to top off with only small amount from my water supply and pray for rain.  When we get a drought I have to put my settling tank in the back of my pickup and drive to the creek.  Man I hate to haul those buckets of water up the hill but it is really good water.

So here is another question.  This has not happened to me before.  I retested my water after placing the lava rocks, grow stones, and food into vinegar to see if they would bubble.  Nothing bubbled.  I then decided to test the pH again with a friend who regurally does this to make sure I was not doing something wrong.  Below is my result.  Typically the low pH is much darker than the 7.6 pH on the low test and darker than the 8.8 pH on the high test.  What one do I go with?

Thanks again for all the feedback!

Roger

Vlad,

I agree.  I wasn't inferring that the chlorine was the culprit, it was only the reason for letting my water set aside.  It was then that I realized the PH had risen.  I read somewhere that would be the case. So actually, you and I agree.  By the way as you suggested, I re-dosed my system last night and will be checking it after 24 hours.  I did check before I went to bed and I had taken the Ammo up to 2.0  So we shall see what we shall see.

Vlad Jovanovic said:

Hi Tradewind. Your right, it's always a good idea to let your tap water sit out in a glass for a couple of days before testing the pH. But it's not the chlorine off-gassing that causes the phenomena you described. My water behaves the same way, and it comes directly from a well/aquifer with absolutely no chlorine or chloromine added.

It is the CO2 that needs to off-gas before you can get a reliable pH reading. See CO2 is soluble in water only under pressure (like in your pipes). When CO2 i dissolved in water it is called cabonic acid (H2CO3) and since it is an acid (albeit a weak one) it will affect your pH reading if you test directly from the tap. Like you say, letting the water sit out for a few days will take care of this 'false low' pH reading... Anywho's...

Roger...pH 8.8 is really quite high. You need yo figure out what is going on there. Lava rocks sold for landscaping purposes in the US, usually first do a tour of duty as part of an industrial or wastewater treatment filtration scheme before being sold off to Home Depot or the local landscaping company or whatever. So they can be kind of a crap shoot. Also, depending on where in the earth's crust they were formed their chemical composition (which may affect their pH) can vary wildly. I'm not saying it's your lava rocks that are causing the problem, but it might be wise to check them out when going about figuring out the root of your pH woes...Good luck 

Tradewind said:

As previously mentioned your water supply is likely contributing to the problem though you say it tests neutral.  Testing the water supply directly from the source often gives bad results.  I let mine sit in a tank to allow the chlorine to dissipate and behold watch the PH shoot over 8.  As my system got closer and closer to being cycled I saw the PH drop.  I am not quite there yet and I was allowing the PH to run high to help cycle the system.  I am running fishless at the moment.  Now if I keep my hands off of the chemicals it will settle out at 6.8.  I too have Lava rock and clay grow media.  So I try to top off with only small amount from my water supply and pray for rain.  When we get a drought I have to put my settling tank in the back of my pickup and drive to the creek.  Man I hate to haul those buckets of water up the hill but it is really good water.

Roger,

Frankly, it has always been a bit difficult for me to match the colors up.  It seems as though the colors on the chart are somewhat faded and off color.  I did purchase another test kit for chlorine, chloramines, and PH.  It is a clear plastic vessel with the colors on the vessel directly beside the test chamber.  The colors match perfectly when a test is done.  I wish the API kit worked the same way.    I recently viewed a video from Nate Storey and he suggested that we all run our PH too high.  He is very successful in his field so I tend to yield to his thinking.  He also points out the problems with carbonates and how they can take away your control of the system.  I was wondering, did you wash your lava rock?  I put mine through some very intense washing before I added it to the bed and it was amazing how much crude I got out of it.  But then like Vlad says it depends on where it comes from.  It did state on my bags that it was free of heavy metals, etc. but that doesn't cover all the bases.   In any case, it does not appear to be driving my PH higher since if left un-tinkered with will gravitate towards 6.8.  If you have another water source, you might want to try changing out some of the water out as it really could be your water.  You may need to only change out a portion in order to achieve good results.

Roger Yerdon said:

So here is another question.  This has not happened to me before.  I retested my water after placing the lava rocks, grow stones, and food into vinegar to see if they would bubble.  Nothing bubbled.  I then decided to test the pH again with a friend who regurally does this to make sure I was not doing something wrong.  Below is my result.  Typically the low pH is much darker than the 7.6 pH on the low test and darker than the 8.8 pH on the high test.  What one do I go with?

Thanks again for all the feedback!

Roger

I washed all the rocks before they made it to the grow bed and then ran the system to wash them some more. I will test the water after I let it set out a while. I am confused why one pH test shows a normal range and the other shows over 8.8.

Roger

Hmm...I've never used the API kit...so someone else will have to chime in on that front. I don't really know if their "high/low" kit is suppose to take into account a diurnal swing, or what the deal is there? Try buying a 'regular' pH test kit at the local pet store and see what happens...

@Tradewind...it just seemed that way, sorry. Hopefully you should be done cycling in the next few days :)

Roger Yerdon said:

I washed all the rocks before they made it to the grow bed and then ran the system to wash them some more. I will test the water after I let it set out a while. I am confused why one pH test shows a normal range and the other shows over 8.8.

Roger

Roger,  I replied to Vlad with this same comment, I am not sure but I think I have the answer to those PH numbers.  When the regular PH shows 7.6 that is the limit of what it can go too, it might be 8 or 9 or whatever but it is definitely not less than 7.6   The PH high picks it up from there showing you a reading of what looks like to me 8.2.  Like I have said before those colors just do not match up very well.  In any case it seems to make sense.

Roger Yerdon said:

I washed all the rocks before they made it to the grow bed and then ran the system to wash them some more. I will test the water after I let it set out a while. I am confused why one pH test shows a normal range and the other shows over 8.8.

Roger

@Roger - API makes a 'Wide Range' pH test kit.  Sometimes marketed under different names.  I like it much more than the one you are using because the colors are very easy to read/

Hi Bob,

Anything that would make the colors easier to match is a winner for me.  I mentioned earlier that I had picked up a small kit just to test for chlorine and chloramine; it also included a Ph test as well.  This one is very similar to the one I bought.  It is very easy to use and the colors match perfectly.  When it comes time, I think I will replace my current kit when ones made like this one.  In this picture the test has been completed and the two center cylinders are showing the results the sides are the references.  It is very easy to read and the results are the same as my other test kit.

 

Bob Campbell said:

@Roger - API makes a 'Wide Range' pH test kit.  Sometimes marketed under different names.  I like it much more than the one you are using because the colors are very easy to read/

I sent the picture into API and they are still working on it.  I will update everyone when they reply.  I guess my fish are still surviving, but my plants are a bit sad looking.  Hopefully I can get this figured out.  Thanks again for everyones input and time!

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