Dozey

This is only how I understand it but that doesn’t mean I understand it correctly.

I think the 1” rule is for little more then a planning stage. The reality is that you can only introduce a few fish at a time anyways. So your weekly water readings are going to be a far more accurate measure of your stocking capacity.

Assuming ammonia and nitrites don’t climb above zero…
If your nitrates are hitting 20ppm between weekly water changes you could consider your tank stocked. Or you could slightly over stock and increase the amount of water changed or the frequency of your water changes.

If however you are showing ammonia or nitrite reading between weekly water changes this would be an indication that you have over stocked the tank too far. As long as the reading are still fairly low after a week (0.25 for example) you could likely keep the stock and just increase water changes while the stock thins out.

≈ D ≈