The Why And The What Of Water Changes

As we feed the animals we keep in our aquariums, waste builds up in these closed systems. This article will focus on how that waste is processed, and the easiest and original way for us to get rid of it.

What is Fish Waste Actually?

Fish excrete waste in the form of Ammonia (NH3) which is very toxic to life. This is the start of a process known as the Nitrogen Cycle, by which fish waste is turned from toxic Ammonia into less toxic Nitrite (NO2) and then nearly non toxic Nitrate (NO3). These jumps are done by nitrifying bacteria, and Nitrate in the home aquarium is generally the end of the line (there are denitrifying bacteria that can go a step further and break down Nitrate, but that is a discussion for a different time).

Taking Good Care of Bacteria

New aquariums need to be cycled, but what does that mean? Basically the cycle is the waiting process from adding food, or an ammonia source to the aquarium, until you can see that there is no ammonia, nitrite, and have nitrate building through testing your aquariums water. At this point, it should be safe to start adding livestock to the aquarium. So, how do we get the bacteria in our tanks to execute these vital processes?

Cured Rock: Cured rock can mean rock from an established aquarium or rock being held at your LFS in a living system. This rock will already be colonized with the beneficial bacteria so it gives you a head start on the process! Depending on the quality and cure of this rock, you may avoid the cycling process altogether by doing this. Bacterial Supplements: You can buy bottled bacteria to add to your aquarium that will help kick start the colonization process. Dr. Tim's line of bacterial products and Tropic Marin's Nitribiotic have our highest recommendation.

Adding Waste: Decomposition of protein is what creates ammonia, and so adding some fish food or another source of ammonia (you can actually buy pure ammonia for this purpose) will give your tank the ammonia it needs, and believe it or not, these bacteria will find your aquarium no mater where you are and start colonizing appropriate surfaces within the tank. This is the slowest method, but it does work!

Lastly, your bacteria need a place to live. For the most part in marine aquariums this is done through using porous, natural reef rock. There are synthetic alternatives available now that are not mined or sourced from the ocean as well. This will give your bacteria the surface area needed to live and reproduce to a population that can filter your aquarium. If you don’t have rock in your tank you will need some biological media in a high flow area so that they can colonize that.

So…I have Nitrate. Now what?

While Nitrate is mostly nontoxic, research is now starting to show that elevated levels of nitrate over long periods of time can be negative for the health of some marine organisms. A little bit provides nutrition to things like corals in your aquarium, and is a good thing, but too much Nitrate could result in unsightly algae blooms and poor fish immune response. How do we prevent this, and keep our aquariums looking clean? While there are many chemical, or biological methods for nutrient control in marine aquariums today, the original, tried and true method is to perform water changes, by which we remove dirty water from the aquarium, and replace it with clean water. Here’s how: Find an appropriately sized container. Plastic containers generally work best, and you should search for one that is food grade. Brute trash cans are a favorite for people with large aquariums.

Get a heater, and a pump that can mix the entire volume of water

Get clean water: you can buy RODI (Reverse Osmosis, Deionized filter water) or even mixed saltwater from your LFS, or you can buy an RODI unit (this seems intimidating, but is not) and set up another container to hold the water you filter to be ready for you when you want to do a water change.

Fill your mixing container with water, turn on your pump and heater to match the temperature of your display tank, and then slowly add a quality salt such as Tropic Marin to a salinity that matches your aquarium.

All salts are different and thus dissolve at different rates. You want the salt to be completely dissolved and the water to be very clear before adding it to your aquarium. If your water is clear, and your temperature and salinity are a match you are ready to do some glass cleaning and tank cleaning.

When you're done scrubbing, remove the same amount of water that you have mixed and ready by using a siphon to “vacuum” your substrate. This removes a lot of detritus (partially broken down stuff like settled waste, debris and any excess food) that would otherwise get stuck in your sandbed).

A good way to make sure that you don’t remove too much waste water is to drain into a container the same size as the one you mix your salt in. Mark the inside of both your mixing and your draining container at whatever volume of water you've settled on for water changes. This makes mixing and removing the same volume very precise every time!

So, What Just Happened?

Congratulations, you’ve just performed a water change. This has removed waste products & detritus and had the added (and crucial) benefit of replenishing nutrients in your aquarium. So the last remaining big question is: “How big should my water changes be?” The general answer is that if you are matching salinity, and temperature and letting your salt fully mix, you cant overdo it. Some aquarists perform very large water changes in this fashion even on small aquariums with sensitive invertebrates, fish and corals. Most people wont have to do this, and it might be cost prohibitive with larger tanks, so weekly water changes of at least 10% of your aquariums volume are generally recommended. Removing more than 50% of the water weekly is generally overly costly, unnecessarily laborious and not recommended. If you are noticing that you have too few nutrients when you test your water or your corals are reacting adversely right after changes, and/or do smaller changes. Finding a lot of nuisance algae? Larger water changes might be part of your solution. We hope this has helped you better understand the why behind the what of water changes. Don't skimp, they are an important part of keeping marine (and freshwater too) aquariums. Head over to your LFS, buy some quality salt from Tropic Marin, and tell them Quality Marine sent you.