Then you do not toast the element if you flip the switch by accident. Then once the heater is filled, turn on the circuit breaker and then flip the switch as needed. See this pic of the circuit breaker on my T2499. Let us know if there is any wording at all on that switch. Good luck.
To lower the pH level of soil and make it more acidic, vinegar can be applied by hand or using an irrigation system. For a basic treatment, a cup of vinegar can be mixed with a gallon of water and poured over soil with a watering can.
Adjust pH by adding PH Up or PH Down solution. Your goal is to get your water in the right pH range for your growing medium. If your pH is too low, you need to add PH Up, and if your pH is too high, you need to add PH Down in order to correct the pH. Re-test to make sure pH is in proper range.