Phytoplankton Dosing Guide

If you have never dosed phytoplankton in your tank then the starter dose is 3ml per 10 gallon for 2 weeks. Test nitrates and phosphates to see if they went down or stayed the same. If so double the dose. Repeat those steps again until you get to 1ml per gallon. If you have already been dosing phytoplankton then start at 1ml per gallon. These stages can be weekly as long as you test weekly! If you start to see a green film algae form on glass, sand or rocks, cut back your dose or stop dosing for a few days, this is a sign the tank is not consuming the full dose. 

If you are treating an issue like dinos, cyano, diatoms, or algae then you can dose up to 2/3ml daily until the issue clears. Just be sure to test nutrients often to ensure the tank is consuming the additional phytoplankton or it’s being filtered out fully.

When to dose? If you are treating an issue it’s best to dose at first light. The longer the phytoplankton has under your lights the better. It needs the light for photosynthesis. During this process is where the nutrients (phosphates, nitrates, heavy metals, etc.) are used up and help to produce the vitamins, pigments, fats, aminos, acids, lipids, etc that corals love!

If you are dosing for coral food, then it’s best to dose when your corals are in feed mode. SPS dominant likely a lights off feed is better typically as they have better polyp extension at night. Most other corals would benefit from a dose during lights on periods as that’s when they are typically open and ready to opportunistically feed.

Whenever you dose, turn off skimmer, UV and other mechanical filtration for at least an hour. All of these will begin to filter any remaining phytoplankton that wasn’t consumed by coral or filter feeders like copepods. Once it’s consumed or filtered out the nutrients not used during its photosynthesis process will be exported!