Here’s something else I was playing around with to add along with Randy’s awesome articles:
Nitrate (the aquarist’s nemesis), the last step in the nitrogen (ammonia) break down process (nitrogen cycle). Well, almost. Nitrate CAN eventually go to nitrogen gas but I’m not sure how feasible that is in our tanks. So, how do we get rid of it or minimize it?
Matter cannot be created nor destroyed only changed or redistributed, therefore, nitrate can’t increase in our tanks unless we add nitrogen (in some form). Nitrogen is added every time we feed AND to a small extent perform water changes. Yes, even our salt contains nitrogen. However, the nitrogen (nitrate) we take out of our tanks when perform a water change should be greater than the nitrogen we put in. Therefore, water changes are a good thing (along with skimming). So that leaves us with food. We have to keep feeding our fish. If you could answer the one question of how much nitrate you fish/tank produces from the food you provide, you could easily determine what percentage of a water change you would need on a regular basis to keep nitrate at bay. To determine this, however, is a problem since the test kits we buy aren’t sensitive enough. The nitrate test would need to be performed by ion chromatography or other means.
Below is an example of how nitrate can be reduced in out tanks. You can easily do this on an excel spreadsheet (again if you knew how much nitrogen/nitrate you put in your tank). Here are the assumptions: your tank is at 10 ppm nitrate, your fish (from the food) along with any uneaten food produce 0.5 ppm of nitrate per week, you perform 10% water changes per week. And I’m also assuming the nitrogen you add from your salt is negligible. In this example shown below, after 6 months (26 weeks) of 10% weekly water changes you can reduce your nitrate in half. It’s interesting to play around with number that you use for the amount of nitrate that is produced. If you produce 1 ppm a week instead of 0.5 ppm and you still perform a 10% change you will only reduce 10 ppm to 9 ppm in six months! Also interesting, try playing around with your initial 10 ppm value, you we’ll see that after 6 months your initial nitrate level doesn’t really matter that much. It’s the amount of nitrate that is being produced on a regular basis that is the key. And the key to that, is, to stock your tank appropriately: do not have too much livestock per gallon. Hope is helps.
Week 1 10.00
Week 2 9.45
Week 3 8.96
Week 4 8.51
Week 5 8.11
Week 6 7.75
Week 7 7.42
Week 8 7.13
Week 9 6.87
Week 10 6.63
Week 11 6.42
Week 12 6.23
Week 13 6.05
Week 14 5.90
Week 15 5.76
Week 16 5.63
Week 17 5.52
Week 18 5.42
Week 19 5.33
Week 20 5.24
Week 21 5.17
Week 22 5.10
Week 23 5.04
Week 24 4.99
Week 25 4.94
Week 26 4.89
