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Cycling Day 20


Ammonia is decreasing as it should but it still has not reached zero. I'm going to call this one 0.25 ppm even though I think it may be a bit less.

The Seachem Ammonia Alert badge shows that free ammonia is now at safe levels which is a great indication and consistent with this result.


Nitrite has increased to 2.0 ppm or possibly a bit more. Some ammonia was consumed and turned into nitrite. This is also a positive result.


Looking at today's result compared to the one from day 16, it seems like day 16 was closer to 10 ppm whereas today's result is closer to 20 ppm since it is a deeper orange. When we looked at the result from day 16 compared to the baseline, which was zero, it looked like 20 ppm. This happens when you look at results in isolation but let's keep in mind that the absolute concentration is not important yet: we are seeing an increase which is what we expect.

The bacteria that turn nitrite into nitrate reproduce a bit slower and they have a fair amount of work to do to consume the existing nitrite, so we need to give them more time.


Wait. What? We haven't mentioned phosphate before. I don't like surprises.

I thought I would sneak this in here since it will become meaningful soon. Phosphate is another compound that is created when waste and uneaten food decay. Fortunately, it is a good one: it is a nutrient that, like nitrate, is consumed by both algae and corals.

Phosphate is something that we need to measure when the cycle ends, but since our API test kit doesn't include a test for it, we need to prepare now. In my case, I will be using a Salifert Phosphate Test Kit.

While you're buying one, go ahead and also get a Salifert Nitrate Test Kit. Even though we already have a test for nitrate, this one is more accurate and includes the ability to perform a low range test when nitrate is so low that it is not within the range of the API test.

The phosphate test is very easy to perform and Salifert includes clear instructions. One difference between this test and the API test is that once the test vial is ready, you place it on top of the color chart and look at it from above. This test also includes a powdered reagent that you add with a tiny spoon.

I performed the test and found that the phosphate level is barely detectable. The solution was just slightly blue.

We won't need to test for it until the cycle is done and we prepare to add fish. Even then, the concentration of phosphate is not very important so we'll just check it to establish a baseline. It will become important when we get ready to turn on the lights, before we add coral to the tank.


I have turned the heater down to 78°F but we're in the middle of a heat wave and the ambient temperature of the house reaches 84°F. The water temperature in the tank is around 80°F, which means we're done with the reduction and have reached a temperature that will be good for our critters.