Top 10 Reasons Why Water Changes Won’t Keep Nutrients Down
1. Understand the purpose of water changes
A water change doesn't replace the need for filtration and feeding responsibly. Your filtration needs to be working effectively to remove waste and nutrients alongside a regular water exchange schedule. You also need to be feeding correctly for your tank's particular filtration bioload and filtration capacity.
2. Dilution is the solution, adjust accordingly
You can adjust the amount of your water change and the frequency by looking at dilution. A 10% water change is only 10% of your total nutrients. If performed weekly, at the end of the month that is only a 34.4% reduction in total nutrient input. This means nitrates can still rise over time if your filtration is not working effectively to export the remaining nitrate input. You need to adjust how much water you remove based on your particular filtration capacity and feeding (nutrient input).
3. BRS Recommended - 10% Weekly Water Changes
With a weekly 10% water change, you can expect a 34.4% net export of your monthly nutrient input. In most situations, this will provide the necessary level of stability so long as your not overfeeding or neglecting your filtration. The amount of nutrients will never rise more than twice your initial concentration. So if you started the month with 10ppm nitrate, with a weekly 10% water change you will never get over 20 ppm nitrate so long as your nutrient input & filtration capacity remains stable.
4. Frequency Effect
Frequency does matter but not as much as you might think. A weekly water change of 10% is a net monthly export of 34.4% as opposed to a 40% monthly water change which is a net 40% export. At the end of the month, the amount of nutrients you have removed is pretty much the same in both scenarios.
5. Don't expect too much from water changes
Water changes work to slow down the rise in nitrates and phosphates but are not the primary solution. Nitrate and phosphate control is more about your feeding (nutrient input) and filtration capacity and the water changes only complement that balance. If you're having trouble controlling nitrates, start by improving your filtration and evaluating your feeding habits.
6. Don't use "magic hammers" or instant solutions
Water changes can be a much more effective and safer solution to nutrient export compared to some of the other options out there like GFO and carbon dosing. If you find yourself with elevated nutrient levels, perform the necessary water changes to bring them down, then evaluate your feeding habits and improve your filtration capacity to help maintain lower levels moving forward.
7. Make it easy so your actually do it
If you make the process of water changes easier, you are far less likely to neglect it. There are a number of tools and techniques you can employ to make the process easier.
- Use a Python gravel cleaner
- Use a water change pump
- Build a water station
- Automate your RO/DI system
- Mix and store saltwater in monthly batches
- Automate water changes
8. Automate water changes
The easiest and most effective way to perform water changes is to automate them with the use of dosing pumps. There are a variety of products and solutions on the market that help you automate water changes, explore these options to find out if they are the right choice for you.
9. Consider the impact
If you're trying to reduce the need for water changes, consider your feeding habits and think about improving filtration. This has been a regular theme throughout the entire list and really is the best way to control nutrients.
10. Water changes are always worth it
Hobbyists who adhere to a strict water change schedule experience a much higher level of success compared to those who do not.
With over 25 years of experience keeping aquariums of all kinds, Robert has a detailed understanding of advanced aquarium techniques and theory. Working as a professional content creator in the saltwater aquarium industry for over 18 years, his perspective, thoughtfulness for the hobbyist, and a general understanding of the hobby, and industry that surrounds it, allows Robert to write and create digestible content that makes reefing fun and easy.
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