PMDD: Dosing Guide for Freshwater Aquarium Plants

Quality artificial plants in an aquarium sub for the real thing quite nicely, but many aquarium owners take pride in a tank filled with healthy live plants. They contribute nutrients to the ecosystem, and they help keep the tank clean. Keeping healthy plants requires what's called "dosing," which is simply adding nutrients to the water that are good for the plants and not bad for the fish. PMDD (Poor Man's Dosing Drops) is an inexpensive mix of nutrient compounds that can be tailored to meet the specific needs of any tank.

  1. The Basics

    • PMDD was developed in 1996 as a formulation for use in low light, so you should start by controlling the basics before you embark on complicated computations of supplemental nutrients. Excess light leads to higher CO2 levels and an abundance of nutrients, so there is an increase in fish waste. Get the light balance right, keep CO2 levels under control and then focus on the exact dose your plants will need.

    The Ingredients

    • To make the drops mix the following in half a liter of water: one tablespoon potassium nitrate, two tablespoons potassium sulphate, one tablespoon magnesium sulphate, one tablespoon chelated trace element mix. Most of these items can be found at garden supply stores. You can also try hydroponic suppliers online. Magnesium sulphate can be found at any drugstore under the name ̶0;Epsom Salts.̶1;

    Now What?

    • With a complete mix, start with a few drops per 10 gallons every day. Test your water frequently and keep an eye on iron and nitrate levels. Iron should be around .1 part per million (ppm) and nitrates will range between five and 10 ppm. If you notice increased algae growth, decrease your dosing to every few days.

      Over time, develop different solutions by eliminating one or more ingredient that your tank in particular doesn̵7;t need. For example, if nitrate levels are good but the plants aren̵7;t growing, substitute potassium for potassium nitrate. You can also make separate solutions and gauge what needs to be added when by testing your water. Make one with potassium sulphate, one with potassium nitrate and one with magnesium sulphate and trace elements.