Help needed from Chile!

[Marko]

Hi everybody!

We are two Chileans that are trying to get our first aquaponic system running in Santiago and we have so much questions!

However, one of them is the most urgent and we humbly request the community’s assistance and guidance.

We have built a traditional IBC CHOP 2 system, with one full IBC for the fishes (1000 lts), three IBC beds and a sump tank. We have attached a picture so you can see more clearly what we are talking about.

Our problem is that we haven’t been able to find a suitable media for our system. Hydroton and expanded shale do not exist here or have prices we can’t afford, volcanic rock may be an option since there are volcanoes in the south of the country, but availability in our area is a problem and we haven’t found suitable vendors (only Little bags for the grills).

So, we are trying with gravel, but we can’t seem to find anything that keeps the ph of the water at aceptable levels. We have been testing experimentally with different sources using destilled water and electronic ph meters (calibrated) and none of the samples tested have been lower than ph 8.

Our question is: Is it possible to use this medium and expect the cicling process or artificial ajustments with HCL to stabilize the ph of the system at an aceptable level? Or should we keep looking?

Thanks in advance!

[jackalope]

Hi There, and Welcome to the Forum

I would not use the 'lava rock' that is sold for gardening/landscaping. I have tried out a couple of them from Ace Hardware, and they are a very soft stone that will dirty up the water as they dissolve - I don't know what kind of lava that is but it isn't for me. I have used pea-gravel (I don't know if you can get it there in Chile) and I remember in the past finding that there was a type of rock (granite or quartz come to mind, but I'm not sure) that is PH neutral. I'm at the end of my internet time, so I can't surf for it right now, but if you haven't found out by the time I get back into town, I'll try to see if I can find it - I believe it was on Wikipedia.org. Here is an article that may help you in determining the PH-value/lack-of-PH in your local rocks/gravel.
Clik

Once again, Welcome to the Forum

[bcotton]

It's inaccurate in that you dont know how much PH, but a trick for testing your PH is to put a small amount of media into some vinegar and if it bubble's it has a high PH.


As far as adjusting the PH of media with acid, it depends. Theoretically, High PH is just extra protons and adding a lot of liquid that has extra electrons should balance out , right? To do this you would need to know your PH AND your alkalinity to math out exactly how much acid it will take.

For example, my expanded shale buffers PH at 7.8 and it is highly alkaline. Over time i added about a gallon of phosphoric acid to my system (30ml at a time). I could lower ph to 6.8-7.2 for a couple of days then it would slowly bounce back to 7.8.

I gave up and just accepted the positive aspects of having a stable PH and stopped worrying that it was higher than i wanted. Maybe in a decade or so the naturally occurring mineralization will bring it down.

brian


brian

[Oliver]

Marko,

What is the pH of your incoming water? This is important to know in determining how the overall system pH will be once your fish start to grow out. The bacteria need a high pH in order to function at their best. A pH of 7.5 is a good number. Your pH will fall once the fish start to grow out. It is important to make sure that the media in your grow beds does not keep your pH too high. 8.0 is probably the upper limit when your system is new.

The main problem with a high pH is that you will have to watch your ammonia level very carefully, for if it goes too high it will be toxic to your fish. The plants like a lower pH but most will grow in a higher pH water.

Again, what is the pH of your water coming into your system?

Oliver