Joshaeus
HI everyone! My blackwater 5 gallon is doing well for the most part, but is showing some odd behavior I thought would be best discussed here. I have been trying to lower the PH with API PH down, but in spite of the fact that the water is either distilled or passed through DI resin (and, either way, has virtually no hardness and very low TDS before the PH down is added) I cannot get the tank water to have a PH lower than 6, even with the recommended dose of PH down; I have not added anything to the tank since its setup that would have added carbonates (the substrate is leaves, peat moss, and inert sand; the filter is inert clay hydroponics media that I confirmed was inert through testing; the Thrive C reduces the PH; and I am feeding fish flakes to cycle the tank, but I tested those yesterday by mixing some with vinegar in a dry container and they did not react with the vinegar). I am going to try a double dose of PH down with the new water change water today, but for now I wanted to ask...are there any bacteria or other aquarium organisms that would consume sulfates and thus push the PH up? Alternately, can the simple process of CO2 being dissolved into the water by gas exchange and respiration add enough carbonates to prohibit the PH from dropping any lower? I had a 5 gallon blackwater tank in the past that had its PH reduced with sodI'm bisulfate; the tank would have a PH of 4.2 after the water change, but the PH would rise to 4.7 before the next water change (I had assumed this was due to a residual amount of carbonates reaching the tank when I fed baby brine shrimp, but this new tank has not been fed any brine shrimp yet) and the TDS of that tank would drop over the course of the week. Thanks