7th of March
In the previous posts of the series, I wrote about planting the seeds and transplanting to the hydroponic system. With everything checked and working, I felt pretty confident: what could go wrong?
Well, the substrate did: the expanded clay was not acidic enough. As the nutritive solution passes through my cheap arlite its pH grows. I tune the solution around pH5.8 at night and it gets to 6.4 in the morning. Nanny was a good help, first alerting that pH was too high just hours after adjusting, then helping me discover the cause. At the beginning I didn’t know it was the substrate, but it soon became clear by looking at the graph. Below there is an actual screenshot of Nanny’s app. You can see that last night I added too much acid to the solution, and it dropped below my intended 5.8, but not for much, so I didn’t correct it. More interesting: see how the pH grows in small steps? Well they happen while the irrigation pump is working.
This inconvenient keeps happening today. I won’t be able to change the substrate until the end of the culture, so I am stuck with an oscillating pH which I adjust every day. Although it is not ideal the tomatoes seem to be happy. I know that this problem will actually decrease productivity and I will do better next time. Remember to check the acidity of your substrate; some arlites need conditioning before use. That means putting them in a solution with the intended pH for a week. Use pH down, diluted nitric or phosphoric acid to adjust it, and monitor the pH through the process.
8th of March
Other than that, taking care of the plants is a wonderful experience. Only two days after transplanting I saw tiny white roots exploring out of the jiffy. 😀 That is the picture at the header of this article.
15th of March
Fast forward a week and one solitary root had found its way to the reservoir. That is when I could still lift the pot to access the
deposit. I can no longer do it. According to the experts, now is when I can expect explosive growth. It also means that the solution in the deposit must contain enough oxygen for the roots. I increased the watering frequency to help with that: the solution areates very well when passing through the arlite.