Update on pH imbalance : the mystery slowly unfolds

9:41 pm in Nutrients, Plants, questions by Louise from Quebec

Hi, everybody !

After several plant casualties, my windowfarm is recovering from its pH fever. The lettuce survived and started to grow again, as the nasturtium, three basils and most of the peas (these lasts started to flower, as a matter of fact. Beside a thorough clean-up,  the only thing I did for those survivors was to entirely change the composition of their nutrient solution.

So, right now, my upper reservoirs contain water from the tap (pH 7, has been sitting at least 24 hours to let chlorine evaporate before use) and an organic nutrient bought at the Hydroponic store : Iguana Juice Grow (it automatically gets the water pH down to 5,5 but smells like dead fish – really awful since it gets the room smelly at times). Take note that my system is working on gravitation, so I have to refill the reservoirs by hand, something I need to do about every four to eight days, usually, depending on the dripping flow. Therefore, the water doesn’t recirculates in the system unless I decide to reuse the contents of the bottom reservoir.

So, I started anew in one column, cleaning up everything, boiling the clay pellets, discarding the old rock wool and using fresh nutrient solution with Iguana Juice and my worm compost tea. Then I monitered the pH very closely.

Here is what I discovered :

1. My precious worm compost tea has a pH over 8,5 ! I never thought of testing it before my plants started to suffer very seriously. I always tested my pH after mixing in the nutrients and a few milliliters of vinegar to start with. Take note that within one column of my surviving plants, the pH would rise from 5,5 at the source up to 8,5+ in the bottom reservoir.

In the new column, the same phenomenom was observed, but to a much smaller extent (pH at 7 in the end). So, I stopped everything again and dumped the water solution to get rid of the worm tea.

Hypothesis : I use, from time to time, egg shells to protect my worm compost from too much acidity. Obviously, I overdid it. And I think that microscopic eggshell particles lodged themselves within the rock wool, very slowly dissolving into the dripping water flow, thus affecting its pH.

2. Even after my stopping from using worm compost tea, the pH in the reservoirs still has a tendency to slowly (within 4 days) go back up from 5,5 to 7 right inside the upper reservoirs (therefore, it does that without getting in contact with the plants or the wool rock, or eggshell particles).

Hypothesis : there could be in the city water a kind of pH stabilization agent that would slowly raise it back up. But I think that I can manage this imbalance by readjusting the pH every other day.

In the meanwhile, I isolated 50 of my worms in a new container to start a new compost farm. I will monitor its pH very closely to try to produce a worm tea with a pH of 6 or 6,5 at the most without any eggshells in it.

I intend to leave the two old columns as they are (with the old rock wool and the surviving plants), to see if the pH alteration effect wears off. The two other columns will receive new plants in new rock wool, and no worm tea will enter in my nutrient mixture until it has a more suitable pH reading !

All this thrilling mystery is fascinating and I have the feeling that I learn a little more everyday, although it was heartbreaking to see my plants die and quite panicking not to have a clue as why.

I’ll keep you posted.