Sometimes against my better judgment, I do stupid things. This was one of those times......
If you have been following along with the aquaponics system I have been struggling with pH being too high since the beginning. This has had a negative effect on growth for far too long and I was beginning to get impatient. The results of my actions here are not entirely negative, but far from optimal.
It started with my filling the grow beds with the wrong type of rock in the beginning, river rock containing calcium carbonate. This caused the pH to be stuck at 8.2 and no matter what I did (adding vinegar, phosphoric acid, etc) nothing would lower it below that. I then switched out all of the rock with a new type which is pH neutral and that made an impact right away. However, I could still not get the pH to drop much below 8, it would keep bouncing back. I then discovered that my hard water contained high amounts of calcium carbonate and so I added a filter to the auto top-off. This started to make a bigger impact and I was able to get the pH dropped down to 7.5-7.6 over a period of about three months. I had to keep siphoning off water and trying to let the new filtered water slowly replace the hard water over time.
Having run this system at a high pH now for about a year I was starting to get impatient. This is where I went wrong. At this same period I was also just getting my new Tilapia added to the system and getting then used to the water conditions. I began looking for something stronger than the vinegar I had been adding to lower the pH and thought that a hydroponics pH down powered should do the trick. It was advertised as a pure phosphoric acid which would add phosphorous to the system and lower the pH. This was going to finally get my into the 6.5-70 range that I wanted to be at and I was excited to get the product and give it a try.
I know that changing pH drastically is a bad idea, especially with new baby fish, especially with a full cycled system, especially when I didn't read the label and the pH down power contained Citric Acid! Citric acid is a powerful antibacterial and will kill the needed bacteria that are the heart of the aquaponics system.
I started by adding the power one teaspoon at a time every couple of hours and testing the pH. The first day was exciting and I was able to drop the pH to 7, no fish dead, and all water tests looked good. Then I discovered the label with that listed citric acid as a component in this pH down powder. At this point I probably should have stopped using it but I was so close to getting the pH down to 6.5 and thought that if it was only a small component of the pH down product it would probably be ok.
The next day I came down to the system to discover dead fish and ammonia levels off the charts. I had killed the bacteria colony and probably all of them. The new fish were struggling to survive and I quickly saved the surviving 17 of 30 and moved them to a small tank away from my stupidity.
The silver lining here is that the pH is now at exactly 6.5, however it is going to take weeks if not months for the system to balance back out. Many veteran aquaponics system owners have a similar story to tell and so I thought I would share mine. I hope that this helps someone else out there to be careful and never add anything that contains citric acid! This is proof, even in small amounts it will kill the bacteria!
API Freshwater Master Test Kit - http://amzn.to/1xGbMDA
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