This is the dose I use, but I do half every day instead of a full dose every two days.
If there is not a huge amount of light, or if there aren't many plants, they will not be using the carbon very quickly so it might pay to minimise the dose. However, I have used more than double the dose for weeks at a time with no problems, ever. I always am careful to gradually increase the dose over time (and dilute it in water before adding it).
:lol: Submarines...I love that!