Can Water Changes Alone Keep My Reef Tank Parameters Stable?
Can I maintain a stable reef aquarium without water changes?
While it is "possible" to maintain a reef aquarium without water changes, it's not recommended as a viable, long-term approach. 99% of success is found when you adhere to a strict water change schedule. Yes, filtration technology combined with dosing and water testing allows hobbyists to maintain stability but that is often only temporary. Without water changes, you drastically increase the risks of experiencing water quality issues and chemistry imbalances.
We are all human and missing a water change happens to the best of us. The key takeaway here is don't fool yourself into thinking water changes are not necessary just because things "look good" in your tank.
Benefits of regular water changes:
- Helps to maintain a balanced water chemistry
- Helps remove waste and dilute excess nutrients
- Prevents "salinity creep" and trace element imbalances that are common when using two-part additives
- Provides you with the peace of mind that your corals are getting everything they need to thrive
Can weekly 20% water changes support stable water parameters without the need for dosing?
Generally speaking, weekly 20% water changes alone will only be sufficient to maintain stable parameters in new reef aquariums that contain little to no corals. Once corals are added to a reef aquarium, they begin to grow and start consuming elements. That rate of consumption will eventually overcome what a weekly water change supply. Dosing will inevitably be required to supply corals with the necessary elements they need and to avoid dramatic shifts in water chemistry in between water changes.
If you are not testing and dosing a reef aquarium that contains corals, you will inevitably run into water chemistry issues. This is especially critical for aquariums housing LPS and SPS corals. Learning how to dose and maintain stable water chemistry via frequent water testing is an important skill for successful reef tank owners to grasp.
Are water testing and dosing required to maintain a successful reef tank?
Periodic testing and using additives to maintain major water parameters are necessary and important aspects of keeping a reef aquarium. Water testing allows you to identify swings in parameters before they get to the point of irritating and even killing your corals. Proper dosing of additives corrects those chemistry imbalances effectively and safely. If you wait until the symptoms of poor water quality or imbalanced water chemistry are visible, it's already too late - the damage is done.
This is especially important in reef aquariums that contain LPS and SPS corals because they will consume calcium and carbonates from the aquarium water as they grow.
While corals are very adaptable and even when they appear to be "alive", they are most certainly not thriving if the water chemistry is not stable. By the time your corals show signs of stress from water chemistry, it's difficult to rebound and takes those corals a very long time to recover.
Can I maintain stable parameters in my nano reef tank with weekly 50% water changes?
The answer is maybe. If you have a small nano tank (25 gallons or less), you can achieve stable parameters without dosing so long as you're performing 50 - 70% weekly water changes. This also might be possible in aquariums that only contain soft corals. We still recommend that you periodically test the water chemistry to verify stability but dosing the tank may not be required. Should you experience a slight imbalance, a large water change of 50% or more should get you back on track. This is ONLY possible when these large 50% water changes are strictly performed every week. Success is all dependent upon the rate of element consumption by your corals and the only way to verify the stability is to perform regular water tests.
If you have an aquarium any larger than 20 - 25 gallons, it's difficult to maintain such a considerable water change regime which is why dosing is necessary. To dose correctly, you must be performing frequent water tests. If you keep SPS and LPS corals, they will eventually consume the elements beyond the rate at which water changes can supply them. If your stony corals are not consuming elements at this rate, they are not thriving and their health will likely diminish over time.
How often should I be water-testing my reef aquarium?
When first starting out, it is best to water test every week so you become comfortable with the process and can see how stocking the aquarium with corals will affect your water chemistry. Once established, you can often get away with bi-weekly water tests, even if you're just verifying parameters.
My water tests are always spot on and my corals are healthy, do I need to keep up with regular water testing?
Once you get the hang of dosing your tank and keep parameters stable, it's easy to forget the regular water tests but this is where we get into trouble. Corals are adaptable, they can thrive within a wide range of water parameters and the idea is to maintain your parameters within that range. As your tank matures, these corals will begin to consume more and more elements which means your water parameters will SLOWLY shift over time. If you do not identify drifting parameters and adjust your dosing regime accordingly, you will eventually fall outside the suitable range and corals will suffer. If you wait until corals show signs of stress, the damage is already done.
Water testing will help you to better identify drifting water parameters and keep those parameters within a suitable range without allowing your corals to suffer.
Here are a few reasons your water parameters may slowly drift:
- As corals grow, they consume more elements. If dosing does not meet this growing demand, water parameters will drift.
- Skipping water changes
- Clogged or malfunctioning dosing pump
- Running out of additives, even for just a couple of days
- Insufficient minor and trace element supplementation - salinity creep
What does it mean to "chase numbers" and why is this a problem?
When it comes to reef aquarium parameters, there is a pretty wide range of suitable conditions. The goal is to float inside that suitable range and not allow the parameters to slowly creep outside that range. Minor fluctuations within the suitable range are normal.
If you are constantly trying to pin your alkalinity or calcium levels at a very specific number, you're going to wind up making mistakes. It's just not possible to pin major water parameters to this level of specificity in a reef tank and water tests are not always 100% accurate. You have to account for some level of variability.
Additionally, it's not a good idea to constantly make adjustments and you certainly never want to make large adjustments. For example, let's say your alkalinity drops down to 6.0 dKH. The best approach is to slowly increase that dKH back into a suitable range using additives by about 1 dKH every few days. Trying to increase by 3 dKH within a single dose will further stress your corals and you run a risk of making even an even bigger mistake.
"Nothing good happens fast in a reef tank"
- Expert Reef Aquarium Owner
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