Why do I have low nitrate levels with APT?Updated 2 months ago

In 2hr Tanks, we adopt a nitrate limiting approach that leaves little residual nitrate in the water column 24 hours after dosing. This approach gives stronger coloration for many species and reduces some form of algae in high light tanks. 

Nitrates generally measure zero because of plant absorption, which takes place continually. A standard daily dose of APT3 adds less than 1.6 ppm of NO3, and many densely planted tanks with moderate fish load easily uptake that amount every day. Unlike popular belief, it is never necessary to give an unlimited buffet of nitrogen to plants in order to grow them well.

So when we measure NO3 at the end of day, it reads zero. To counterbalance the lean water column nitrates we do recommend using a rich substrate or enriching the substrate with nitrogen rich root tabs. This allows the plants to draw additional nitrogen they require from the substrate while keeping water column nitrate levels low.

Low nitrate levels in the water column prevents algae forming on rocks in high light tanks.

2hr display tanks such as the one above measure 0 ppm nitrates in the water column consistently.

Adding nitrogen through the root zone allows one to feed plants without facing the downsides of having elevated nitrate levels in the water column.