Saltwater Nuisance Algae
Written by Dan
One of the biggest challenges for any aquarist is algae, but don’t worry there is a way to win the war on algae. Keeping that perfect balance is hard. You need to feed your livestock, let just enough algae grow for your critters that feed off of what grows in your tank, and keeping a nice aesthetic in your tank. It’s tough. It is something every successful aquarium owner has failed at during their time in the hobby at least once. For many of us even more than that.
What is Nuisance Algae
First let’s start by defining algae in general. Algae is both the singular and plural word used to describe plant like organisms which contains chlorophyll but lacks a true stem system as well as roots, leaves, and vascular tissue. They can range in size from microscopic single cell organisms to large hundred foot strands. These are the key features which distinguish it from a typical plant.
In other respects they are very much like what you typically classify as a plant. Some algae are good as they help to remove unneeded nutrients from your aquarium and provide food to copepods, snails, crabs, fish, etc. These in turn then feed other critters giving us the circle of life and Rafiki holding Simba up on pride rock and what not.
There are types of algae that are hard to maintain and can grow rapidly taking over a tank. They can choke out good algae like your pretty coralline algae. Some very aggressive algae will grow over your corals preventing them from getting light and food. These are the ones we want to keep out of our tanks
What causes algae to grow?
All algae feed on photosynthesis from sunlight and gain nutrients from soil and water. The more light and nutrients they have, the quicker and thicker they grow. This is why most experienced hobbyists will tell you to choose an area away from direct sunlight when picking where your aquarium will go. This helps you control exactly how much light you give your tank based on when you cut the lights on and off.
After lighting the amount of phosphates and nitrates in your aquarium will be the next biggest contributors to how much algae you have. These nutrients will be introduced to your tank by the food you provide, animal excrement, and decomposing animals.
Overfeeding can lead to a very quick algae bloom. In an established tank the only new source of nutrients are food, water changes, and dead animal. We all try not to have the last option and are not doing water changes daily. This means 95% of the nutrients are coming from the food you add. So, adding more than your tank can handle will quickly start an algae bloom.
Ensuring you are not over feeding, that you are doing routine maintenance, and that you have the appropriate level of filtration will keep the phosphate and nitrate levels where they should be.
Keep it clean with a cleanup crew
You will never be able to keep your parameters to the exact specification to never have any algae. Having creatures in your tank that eat algae is a great way to help keep what does grow under control. Many common algae eaters are snails, crabs, and even fish like tangs that will devour algae on rocks. These creatures are commonly referred to as the aquarium cleanup crew.
Your crew can get the uneaten food, detritus (excrement), and algae. Make sure you have a diverse crew to handle all aspects of cleaning.
Don’t make the mistake most beginners make and go by the numbers many places selling these creatures suggest.
Each tank is different and produce different amounts of algae based on many, many, many different factors. Ease into your Cleanup Crew, throwing to many creatures at an algae bloom will clear the bloom but when all the food is gone and they begin to starve they will die and refeed the next even bigger bloom.
Check out our full article on selecting a cleanup crew here.
The right amount of light is key
Since we will always have some amount of algae in the tank how do we keep it from growing? Step one is by reducing the amount of photogenic time it has. Fish don’t need light to live so in a fish only tank keep the light on about 8-10 hours a day and use a timer so it cuts on and off around the times you will be there to enjoy it.
In a reef tank it gets more complicated because you will be lighting for 10-12 hours and depending on your corals, you will have very intense lighting during much of this time. In these tanks maintaining the algae via filtration is even more key.
Remove and prevent algae with proper filtration
We know adding food to the tank introduces nutrients. Even after they are consumed by your livestock, they don’t leave the tank. They just become something else, something yuckier!
So how do you get these nutrients out? 20 years ago when I got into the hobby the number one answer was regular water changes. It still is for many tanks, especially smaller tanks where this can easily be done. But making a major water change on a huge tank every few days just isn’t practical.
Luckily advances in filtration systems over the past 20 years have helped reduce how often these water changes are needed. For some aquarists I have even seen where they don’t do any water changes.
Assuming you have a sump, filter socks are your first line of defense in your filtration system. They will catch all the big particles of food and waste that get sucked into your filtration. Unless you change your socks regularly preferably everyday but at least every few days; the socks do nothing but collect all the gunk in one place that all your water flows through.
Next is your protein skimmer. Making sure you have a big enough skimmer for your water volume is key. I am a firm believer in using a skimmer rated a little more than your overall water capacity to give you some wiggle room with over feeding, overstocking, and under sock changing. The protein skimmer is going to clear little microscopic particles that you really can’t see with the naked eye but will give your water a dingy or green color. We have a full write up on how they work as well as several popular models in our Ultimate Guide to Protein Skimmers.
Refugiums are simply an area outside of your main display tank where you grow algae intentionally. Most commonly chaeto algae. Lighting is run on this section much longer than your regular tank giving the algae a longer photogenic period than your display. The growing algae eats all the excess nutrients reducing and even eliminating the ability to grow it in the main display. You simply clear out a portion of the algae from the refugium every couple weeks leaving enough to keep growing from.
An alternative to the Refugium is an algae scrubber. The concept is the same but rather than having the algae grow wild in the tank a system is built to funnel water past a mesh of some type where the algae can grow. The constant waterflow allows for even more algae growth which can remove evem more nutrient than a refugium. You must be careful that you are not stripping your tank of all its nutrients however.
Only use RO Water Reverse Osmosis Water
Reverse Osmosis is a process that will remove a very large majority of the contaminants found in your tap and well water. The Reverse Osmosis system will push the water under high pressure through simi porous materials.
The RO process is capable of removing 99% of dissolved salt, particles, organics, bacteria, etc. from the water. This highly pure water removes all the things you don’t want in your system and then some.
By using RO water you ensure you are not introducing things like silica which will feed diatom growth or phosphates that can will feed all algae. Although these minerals are beneficial to you to be drank and are safe for your body, they can hinder the success of your tank.
Have you had issues with algae? Did you clear it up or are you still fighting it? Let us know in the comments
Anyone who tells you they have never had algae issues in a tank is either very lucky or lying. This is an obstacle we all must overcome. Do not let it keep you from enjoying such an awesome hobby. Algae can be removed if it is growing and prevented if it hasn’t yet started.
What is your experience with algae? Let me know in the comments below.