Welcome to Day 25 of the 31 Days to Build a Better Saltwater Aquarium Challenge.

Phytoplankton are the first link in the food chain. They are a basic, plant-like food that many organisms eat, including copepods, rotifers, zooplankton and even some corals.

Today’s challenge is to boost the biodiversity in your tank when you add a dose of live phytoplankton.

Add a dose of live phytoplankton

You can buy phytoplankton online or also at your local fish store, depending on how large and/or specialized they are. There are generally two types of products available. The first and generally most widely available phytoplankton product is a phytoplankton paste. It’s a paste because it is a highly concentrated goo of dead phytoplankton. That makes it a highly nutritious food for some of the organisms in your tank, but if you add this to your tank, it is strictly a food.

There is also live phytoplankton, which means you are purchasing living, breathing cells—which may get eaten or may live for a short time in your system (until eaten or skimmed).

Routinely purchasing phytoplankton to add to your tank can get expensive. If you like what it does for your tank, you might want to consider growing it yourself. It’s a way to add a new experience to your hobby.

You can grow your own phytoplankton pretty easily. It’s fun and makes your basement, kitchen or laundry room look like a laboratory that will impress or scare your friends.

A word of caution

You have to be careful, when adding phytoplankton to your tank, because it is commonly grown with phosphate/nitrate fertilizers (which are things you are trying desperately to remove from your tank, not add to your tank). Live phyto will always be less concentrated than the paste, but it should still be a robust, dark color. If the culture you have is thin and looks ‘watered down’, the culture may have been bottled before it consumed all the nutrients and therefore may have extra nutrients in the water.

Start by adding small amounts and scale back if you see any problem algae.

Phytoplankton in the aquarium

If you want to build a better aquarium, you have to build a better ecosystem, and since phytoplankton are the base of every reef ecosystem, it makes sense to me to add it to our tanks with moderation.  Just don’t get carried away.