[piercho]

IME established reef tanks can soak up a lot of dosed nitrate in just hours. If you are trying to maintain a constant level of nitrate thats measurable it may be necessary to use an automated doser or a slow drip.

It's true that increasing the N:P ratio is likely to change what algae are dominant, and may retard undesirable microalgae and cyano. But I'm not sure how predictable the results of N-dosing iare. We are frequently dealing with levels of N and P that are too low to be accurately measured so it's hard to gage what the N:P is to start with. And the pore water just beneath the surface of the sandbed may be very different than the general water column you are measuring, and it's nutrients in thet pore water that are feeding mat-forming cyanos IMO.

Outer reef waters are oligotrophic and we try to maintain those conditions in our tanks. Adding nutrients is counterproductive, or at least counterintuitive, to that goal. However I think cautious additions of nitrate and iron can be helpful to the health of the tank in certain circumstances. I would consider the basics - like using limewater for makeup water - before undertaking dosing nutrients to resolve dino/cyano issues.