Colombo pH Min is a simple yet effective water conditioner that will reduce the pH of your planted aquarium.
As all plants prefer an acidic water (pH less than 7) it's a good idea to keep the levels low in order to give the plants what they need. Pressurised CO2 will help to reduce pH levels, as will substrates but over time, pH levels can creep up.
Dosage is very simple with this fish friendly solution:
Add 1ml of pH Min for every 5L of water - this decreases the pH by 1 unit.