High PH and Grow Media

[Laurie Roberts]

I have read many forum threads about dealing with high ph and would like to get some opinions from  about what we should do.  We have a flood drain system 2 - 500 gal tanks and 2 5x40 grow beds with 3/4 gravel.  When we got the gravel, IT TESTED NUETRAL.....did not raise the ph however, once the water (well 7.6) ran thru the system, ph went to 9.9 but has stabilized at 8.2 after a few weeks of fishless cycling.  The plants have not grown but an 1" in 1 month although maxigrow had been added at reccommended amount from from the start.  I changed out the water yesterday on one tank and ran it thru a few cycles and the ph is back up to 8.2 so the gravel is the issue along with high ph well water to begin with.  Changing out the gravel will be a huge job but if we dont, are we going to battling it forever.....does it ever leach out ?  If we just add the chelated iron on a regular basis, will that help solve the problem with the plants and will the catfish be okay with 8.2 ph if it never goes down ?  Or should we consider  using a RO filter system on all the water returning to the tanks ?  Before the water change, our numbers had stabilized at 8.2, ammo 0, nitrite 2, nitrate 5 for a couple weeks.  Did I do the wrong thing in changing the water out to try to get ph down without resorting to ph down etc ?  George said I should look at the KH and after reading about that, I am more confused.

[Jonathan Kadish NYC AA Chair]

I would say just be patient, you don't know where the pH is going to settle once your bacteria really gets established. It will come down from where it is now within a few months. Aquaponic systems mature over years not weeks. How did you test the gravel?

[Laurie Roberts]

 thanks Johathan....... I put the gravel in a jar and added vinegar.....no fizzing.  I also just let the gravel sit in my well water for a couple days and tested that with a meter which may or may not be calibrated and tested the gravel water with api test kit and it showed little or no change . Should I treat with chelated iron for the plants  and continue adding ammonia  or can I add my catfish with the ph being so high ?

Jonathan Kadish NYC AA Chair said:

I would say just be patient, you don't know where the pH is going to settle once your bacteria really gets established. It will come down from where it is now within a few months. Aquaponic systems mature over years not weeks. How did you test the gravel?

[Alex Veidel]

Here's a alternate theory: Your gravel is fine and your pH spike was caused by carbon dioxide leaving the water as it was aerated running through your system (carbon dioxide is an acid). Since you're using well water, it's likely very high in kH (carbonates act like a buffer for your pH), which is keeping your pH locked in above 8.0. 

I'd recommend getting yourself a API kH test kit and reporting back with the results: http://www.amazon.com/API-Carbonate-Hardness-Test-Kit/dp/B003SNDDAU...

Alternatively, you could fill up a 5 gallon bucket with your well water and treat it with some muriatic acid to see how much it takes to get your pH down. Muriatic acid is really strong and cheap, so it's great for treating well water. I usually pre-treat my well water in 55 gallon drums before adding it to my system. I don't have my notes handy, but I think it takes somewhere between 1/4-1/2 a cup of muriatic acid to bring my well water down down to 6.5 or so,

[Jeff S]

Alex and Jonathan are right. Once your system really matures you'll be fighting to keep your pH up. I used hydroton and although I never had readings as high as yours my pH stayed around 7.6 for the longest time. Be careful with the acid, it works fast. You can also use lemon or lime juice.

[Laurie Roberts]

alex,

I ran the carbonate hardness test and  kh was 18drops and gh was 13 so your theory could be right . I ordered the iron checker, iron and ph down and my plan is to get the iron in there for the plants, reduce ph to low 7's slowly (knowing it will drop more naturally eventually) , keep adding a little ammonia every other day or so while testing then add my fish once I think it is stablilized unless someone has a better plan ?  

Alex Veidel said:

Here's a alternate theory: Your gravel is fine and your pH spike was caused by carbon dioxide leaving the water as it was aerated running through your system (carbon dioxide is an acid). Since you're using well water, it's likely very high in kH (carbonates act like a buffer for your pH), which is keeping your pH locked in above 8.0. 

I'd recommend getting yourself a API kH test kit and reporting back with the results: http://www.amazon.com/API-Carbonate-Hardness-Test-Kit/dp/B003SNDDAU...

Alternatively, you could fill up a 5 gallon bucket with your well water and treat it with some muriatic acid to see how much it takes to get your pH down. Muriatic acid is really strong and cheap, so it's great for treating well water. I usually pre-treat my well water in 55 gallon drums before adding it to my system. I don't have my notes handy, but I think it takes somewhere between 1/4-1/2 a cup of muriatic acid to bring my well water down down to 6.5 or so,

[Jeff S]

Be stingy with the iron as your plants don't need a lot and it will turn your water brown. Nothing more frustrating than to get everything working and not be able to see your fish.

Laurie Roberts said:

alex,

I ran the carbonate hardness test and  kh was 18drops and gh was 13 so your theory could be right . I ordered the iron checker, iron and ph down and my plan is to get the iron in there for the plants, reduce ph to low 7's slowly (knowing it will drop more naturally eventually) , keep adding a little ammonia every other day or so while testing then add my fish once I think it is stablilized unless someone has a better plan ?  

Alex Veidel said:

Here's a alternate theory: Your gravel is fine and your pH spike was caused by carbon dioxide leaving the water as it was aerated running through your system (carbon dioxide is an acid). Since you're using well water, it's likely very high in kH (carbonates act like a buffer for your pH), which is keeping your pH locked in above 8.0. 

I'd recommend getting yourself a API kH test kit and reporting back with the results: http://www.amazon.com/API-Carbonate-Hardness-Test-Kit/dp/B003SNDDAU...

Alternatively, you could fill up a 5 gallon bucket with your well water and treat it with some muriatic acid to see how much it takes to get your pH down. Muriatic acid is really strong and cheap, so it's great for treating well water. I usually pre-treat my well water in 55 gallon drums before adding it to my system. I don't have my notes handy, but I think it takes somewhere between 1/4-1/2 a cup of muriatic acid to bring my well water down down to 6.5 or so,

[Laurie Roberts]

okay thanks......the water is already dark from the seaweed so that might not make much difference
Jeff S said:

Be stingy with the iron as your plants don't need a lot and it will turn your water brown. Nothing more frustrating than to get everything working and not be able to see your fish.

Laurie Roberts said:

alex,

I ran the carbonate hardness test and  kh was 18drops and gh was 13 so your theory could be right . I ordered the iron checker, iron and ph down and my plan is to get the iron in there for the plants, reduce ph to low 7's slowly (knowing it will drop more naturally eventually) , keep adding a little ammonia every other day or so while testing then add my fish once I think it is stablilized unless someone has a better plan ?  

Alex Veidel said:

Here's a alternate theory: Your gravel is fine and your pH spike was caused by carbon dioxide leaving the water as it was aerated running through your system (carbon dioxide is an acid). Since you're using well water, it's likely very high in kH (carbonates act like a buffer for your pH), which is keeping your pH locked in above 8.0. 

I'd recommend getting yourself a API kH test kit and reporting back with the results: http://www.amazon.com/API-Carbonate-Hardness-Test-Kit/dp/B003SNDDAU...

Alternatively, you could fill up a 5 gallon bucket with your well water and treat it with some muriatic acid to see how much it takes to get your pH down. Muriatic acid is really strong and cheap, so it's great for treating well water. I usually pre-treat my well water in 55 gallon drums before adding it to my system. I don't have my notes handy, but I think it takes somewhere between 1/4-1/2 a cup of muriatic acid to bring my well water down down to 6.5 or so,

[Alex Veidel]

You may want to help your system along by adding some acid. From my own personal experience,  it will take practically forever for the nitrification going on in your system to produce enough acid to eat through 18dKh of carbonate, not to mention the carbonates you add in every time you top off your water. Use muriatic acid, especially if you haven't added your fish already (it's strong stuff, and it can swing your pH before the carbonates have a chance to neutralize it. It can stress the fish out if you're not careful). Might as well take advantage of the opportunity to get your pH in the right place faster.

Also keep in mind that your nitrifying bacteria will colonize faster at a pH around 8.0-8.6, so if you aren't yet satisfied with the amount of ammonia your system is handling, you could wait a little longer before dropping the pH.

Laurie Roberts said:

alex,

I ran the carbonate hardness test and  kh was 18drops and gh was 13 so your theory could be right . I ordered the iron checker, iron and ph down and my plan is to get the iron in there for the plants, reduce ph to low 7's slowly (knowing it will drop more naturally eventually) , keep adding a little ammonia every other day or so while testing then add my fish once I think it is stablilized unless someone has a better plan ?  

[Laurie Roberts]

Alex or anyone else that want to chime in please....

So two months later, fish have been in for a month and water stabilized for several weeks at ph 8 , am .25- .50, nitrite 0-.25  nitrate 0-80.  My kh tests at 11.  I have been testing for iron every couple weeks and add the chelated iron.  The lettuce and rapini, and bok choi look good, zuchinni hanging in there.  Everthing else has not grown much........literally 1" in a month.....somethings not even that.  I thought by adding the iron, I would make nutrients available to the plants.  I have added some seaweed extract on occassion too.  There are things that have been in there 2 months and they are green but less than a 1" tall.  The greenhouse is staying above 40 degrees at night and below 90 in the day and we have sunshine every day mostly.  I have read about the high KH factor so assume it is the problem but not clear how best to deal with it.  The PH has not dropped since the beginning although the KH has come down from 18.  Should I start adding mur acid ? 

My other system has very similar test results but it has no fish and I did a fishless cycling.  Do I need to keep adding amonia until I get the fish..........I have not added any for weeks but it still tests 8.2 , .50 ammonia, 0 nitrites, 80 nitrates.  So are the bacteria creating their own ammonia ?

Alex Veidel said:

You may want to help your system along by adding some acid. From my own personal experience,  it will take practically forever for the nitrification going on in your system to produce enough acid to eat through 18dKh of carbonate, not to mention the carbonates you add in every time you top off your water. Use muriatic acid, especially if you haven't added your fish already (it's strong stuff, and it can swing your pH before the carbonates have a chance to neutralize it. It can stress the fish out if you're not careful). Might as well take advantage of the opportunity to get your pH in the right place faster.

Also keep in mind that your nitrifying bacteria will colonize faster at a pH around 8.0-8.6, so if you aren't yet satisfied with the amount of ammonia your system is handling, you could wait a little longer before dropping the pH.

Laurie Roberts said:

alex,

I ran the carbonate hardness test and  kh was 18drops and gh was 13 so your theory could be right . I ordered the iron checker, iron and ph down and my plan is to get the iron in there for the plants, reduce ph to low 7's slowly (knowing it will drop more naturally eventually) , keep adding a little ammonia every other day or so while testing then add my fish once I think it is stablilized unless someone has a better plan ?