1. New Tank Syndrome

2. Nuisance Algae

3. Cyanobacteria

4. Fish Aggression

5. Fish Disease

6. Aquarium Pests

7. Water Tests & Parameters

8. Calcium, Alkalinity & pH

9. Overfeeding

10. Clean-Up-Crew


1) New Tank Syndrome

This is a term coined for a situation that occurs when a tank is not properly cycled which results in the rapid rise of ammonia and/or nitrites in the aquarium which are toxic to the tank inhabitants.

The most common reason this happens is that your stocking too many fish, too quickly into the aquarium. An aquarium needs time in between new fish additions for the beneficial bacteria population to grow and accommodate the additional ammonia. Precisely the reason we recommend only 2-3 small fish at one time and always give the tank at least 2-4 weeks in between new additions.


If dangerous levels of ammonia show up in your tank, you can add an ammonia detoxifying additive, like Seachem Prime or Amquel, to immediately make the water safe followed up by a series of large water changes. Swap out 25-50% of the water every few days until the ammonia is diluted out. Adding an ammonia detoxifier to the new water is recommended too, just to be safe.

Monitor ammonia levels daily and repeat as necessary until those ammonia levels have subsided and, of course, do not add any more fish to the aquarium until you are confident the tank is cycled and ammonia is no longer a threat. 

As a long-term solution, using bacteria additives such as Fritz TurboStart can also help to add a boost of bacteria. Be sure you have biological filter media in the aquarium as well to provide a place for that beneficial bacteria to thrive.  

It should be noted, a very minor rise in ammonia (+/-0.25 ppm) is normal when adding new fish. You should only become worried when these numbers rise substantially beyond this level and don't come down naturally. 

**Pro-Tip: Add the Seachem Ammonia Alert badge to your aquarium during the first 6 months so you can immediately notice if any ammonia shows up just by looking at the badge. No water test is required! 

2) Nuisance Algae - You Can Do Something About It!

Algae is simply a part of keeping an aquarium. Algae will show up in ALL aquariums, regardless of how experienced you are. The idea is to keep it under control at all times so it doesn't dominate the biotope and be especially careful of certain types of algae or pests. 

Hair Algae and Turf Algae are the big ones that can pop up in new aquariums, seemingly out of nowhere. They can grow pretty quickly and once they are established, it's much far more difficult to remove them. Diatoms are something else that shows up quite often in new tanks in the way of a light brown or rust-colored dust that grows on surfaces inside the tank. Thankfully, these guys are not as much of a threat and are easily removed with regular cleaning.

Nuisance algae are generally fueled by rising nutrient levels in the aquarium. Nitrate and phosphate are direct fertilizers for algae. You should be testing nitrates and phosphates at least 1-2 times weekly for the first 3-6 months to keep an eye on it.

The tricky part here is algae will suck up the nutrients almost instantly if you allow it to flourish. That means nitrate and phosphate may test at lower levels, but you are still seeing algae grow uncontrollably. So long as your test frequently and remove/clean algae at the very first site, you should be able to avoid that scenario.


Should algae show up, you want to physically remove it. This often involves removing rocks from the aquarium, one at a time, scrubbing them clean in a separate bucket of saltwater then placing them back into the tank. Spot treatments with full-strength hydrogen peroxide (outside of the tank) is a great move as well because it can help kill any remnants of algae after scrubbing the rocks.

Always remove and clean algae at the very first sight of it, DO NOT LET IT GROW once it starts popping up. The same case applies to using your algae magnet cleaner or scraper on a very regular basis (every other day). It's far easier to run the magnet every day compared to using a hand scraper or blade to scrape off stubborn, crusty algae. 

The big picture strategy should be better management of your nitrate and phosphate levels.  Do not overfeed, do more water changes, maintain your filters more often - whatever it takes to get nutrient levels under control. Always be mindful of your bioload too.

Too many fish =  nutrient levels the filtration cannot handle = elevated nitrate and phosphate. 


3) Causing A Cyanobacteria Outbreak

Cyanobacteria look like a slimy type of algae but are technically photosynthetic bacteria. It's ugly and blankets everything in the tank.  

This often happens when you find yourself stripped of all nutrients, that's right... when the tank is TOO clean. While it seems silly, the trick with nitrate and phosphate is to keep the levels low but not zero. Too much leads to true algae problems and stripping the nutrients altogether can instigate a cyano outbreak. 

Using GFO or other chemical filter media to the point at which it strips out all the phosphate is a common reason for cyanobacteria to start growing. 


Siphon and remove cyanobacteria at first sight. Balance nitrate and phosphate levels and discontinue the use of any chemical filter media. You may need to feed a little more often or maybe turn off your skimmer for a few hours each day to help get back on track. You will likely have to siphon out the cyano more than once, probably weekly over the course of 3-4 weeks and so long as you balance out nutrient levels, it should be fairly easy to overcome within that timeframe. 

Learn More: How to Prevent and Remove Cyanobacteria From Your Aquarium - Red Slime Algae Control

4) Not Planning For Fish Aggression

This can be one of the more frustrating things that happen with new fish. While you can do all the research necessary, sometimes you get a particular fish that is downright mean. It's more common in smaller aquaria but regardless, there are some things you can try before letting that bully become king of the tank. 


Choosing the right fish, adding them in the correct order, and providing the right habitat go a long way in preventing aggression in your tank. Here are some additional tricks to try should you notice aggression progressively getting worse inside your new aquarium. 

  • Feed more often
  • Create additional habitat or move the rocks around
  • Add a few more of the same species - some fish find comfort in numbers
  • Isolating the aggressor in an isolation chamber for a couple of weeks

If all else fails, you may have to remove the aggressor altogether. Sometimes local fish stores might take a healthy fish back in exchange for credit or maybe you have a friend that will gladly take the fish off your hands. Point is, aggressive fish can pester tankmates to the point of exhaustion that could very well be threatening to their health. Sometimes removal is just the only way to find peace in the aquarium. 

5) Not Knowing How To Treat Fish Disease

This is a difficult one because treating fish correctly is just not something that you can learn overnight. It takes research and extensive experience to really be an expert at fish disease identification and treatments. The good news is so long as you're buying healthy livestock from a reputable store and using proper quarantine procedures at home, you can eliminate a majority of the threats. 


In the instance you run into trouble in the way of disease or parasites in your display aquarium, the best approach is going to be removal and treatment in a separate dedicated aquarium. This drastically reduces the risk of infecting all of the fish in your display and gives the infected fish a better chance at survival. Sometimes that stress-free isolation alone is enough to help the fish heal without any specific treatment.  

Should you wish to try and treat a fish with medications, research is your best friend. Proper identification of the ailment is your first step, then finding a reputable treatment plan from a trusted source. Fish vets are just not something you're going to have access to (most likely). If you are lucky enough to have a mentor in this area, the direct treatment is still going to be your responsibility day in and day out.

6) Not Preventing Pests

Pests are just a part of the game, whether it's algae, aiptasia, pesky inverts, parasites, or coral disease... you're going to experience some kind of pests.  A majority of reef tank pests find their way into your aquarium as hitchhikers on fish or coral frags. This is a case where an ounce of prevention is worth a pound of cure, the best defense is a good offense, be proactive and not reactive!  


Follow proper quarantine protocols with all of your fish to avoid the introduction of disease and parasites. Never allow water from the fish or coral bags into your display aquarium directly. Dip, clean, and observe ALL-NEW CORAL FRAGS before placing them into your tank, even if you trust the source. It is safe to say a majority of these pests are coming from coral frags and the lack of a proper dipping protocol is what puts you at risk. 

While it is true that no coral dip is 100% effective and you will never eliminate the risk altogether, you will drastically reduce the risk and effectively eliminate a large portion of the possible problems on a new coral frag with a simple dip.  Visually clean off algae and physically remove any pests and you are going to be in a much better position in terms of introducing pests.

Should you find pests in your aquarium, there are a variety of treatment options and removal techniques you can employ.  Just do your research based on the particular problem, talk to our experienced customer service team, or have a chat with other hobbyists who have overcome the problem themselves. 

7) Not Understanding Water Test Results

Knowing what parameters to test for and how to interpret those results can be difficult for any tank owner, especially if you are keeping corals. Some parameters are critical and need to be monitored and controlled absolute in that you just can't let them stray without seeing any negative effects.  You then have a plethora of additional parameters that give you some wiggle room but still need to be monitored in order to provide the stability your tank needs to thrive. 

Knowing the frequency at which to test and keeping up that routine is going to be important for your long-term success. The best advice is to create the habit of regular testing early on so it's not such a chore.  


Do the work, learn your water parameters, and how to perform the water tests properly. Stick to a strict testing routine and always record your results in a logbook. It all starts with knowing which water tests are going to be critical to your tank as a beginner. From the chart below, stick to the first two columns throughout your first 12 months in the hobby. Only after adding corals to the tank should you be concerned with reef tank parameters. 

Once you do add corals, start by adding alkalinity, calcium, and magnesium to your regular routine which just so happens to be the next mistake on the list. Trace & Minor Elements include a pretty long list of individual elements that are only present in very small quantities and will only be something of concern for the intermediate to experienced hobbyists that have a considerable or mature population of corals. Not anything you should worry about testing for as a beginner or first-time tank owner. 

Critical Parameters Additional Parameters Reef Tank Parameters
Salinity Nitrate Alkalinity
Temperature Phosphate Calcium
pH   Magnesium
Ammonia   Trace & Minor Elements

Reference the Reef Tank Parameters Chart for a full list of ideal aquarium parameters and their natural ocean levels. We also have some great additional articles and videos about water testing right here in the BRS Education Center should you wish to learn more.  Fact is, water testing and parameters, in general, are one of the more complicated skills you're going to acquire with your aquarium and you will become better at it only through experience. 

8) Trying To Balance pH, Calcium, and Alkalinity

When you start adding corals into your aquarium, calcium, alkalinity and the exact pH levels begin to become more important. While it is critical that you maintain these parameters stable within a particular range, you just may not be able to get them perfect. The amount of CO2 in your home and in the aquarium water has a major effect on the tank's pH, but so does the alkalinity. You could be very meticulous about testing and maintaining your tank's calcium and alkalinity ratio but still experience a less than perfect pH because of too much CO2 in your home. 

Humans create CO2 when we breathe, in a closed home this tends to spike the level of CO2 relative to what you would get in outside air. Since your tank is inside, the natural gas exchange that happens with the aquarium water creates a relatively higher level of dissolved CO2 in the water which then suppresses pH.  The only way around it is to address the CO2 levels because the addition of calcium and alkalinity will not help. 


While the ideal pH of 8.3 in a reef tank will help you achieve maximum growth among your corals, sometimes it's just better to accept that the pH in your tank will run a little lower. Stability is far more important and constantly trying to adjust the pH up only to have it fall again because of the CO2 levels will stress out the aquarium inhabitants. Letting the pH remain stable anywhere from 7.8 - 8.3 is acceptable and whatever number your tank lands on within that range will be your target. Constant pH fluctuations any greater than 0.20 pH can be far worse than a stable pH that runs a little low. 

All that said, there are solutions to help CO2 problems but they don't eliminate the issue altogether in most cases. You can open up a window to allow for better ventilation around the tank for starters. This is an easy one but not always realistic for those living in areas with inclement weather. You can also utilize something called a CO2 scrubber on your protein skimmer or pull air into the skimmer from outside your home, both of which can work well but is just more equipment to maintain and media to purchase regularly. 

9) Overfeeding Your Fish

This is something just about every single hobbyist learns on their own. No matter how much someone tells you not to overfeed your fish, it's just too easy and too satisfying to avoid. Feeding your fish is fun and one of the only times we get the interact with the fish directly. Your fish will almost always accept another meal which tends to evoke emotion in a hobbyist that might trick you into thinking you are not feeding enough.  

Overfeeding leads to excess waste and ultimately elevated nitrate and phosphate levels. That excess waste from overfeeding can directly fuel nuisance algae and other pests in the tank. You fish can also experience obesity and nutritional deficiencies from eating too much of the wrong food. 


Your first step in knowing whether or not you are feeding too much is to monitor the nitrate and phosphate levels in your aquarium. If you find the levels are constantly climbing, you are putting too much food into the tank.  At this point, you have two options - feed less or increase your filtration capacity and maintenance. In many cases, it's a combination of both that does the trick.

If you feel that cutting back on your fish feeding may adversely affect your fish population, you should first evaluate your feeding routine and the quality of the foods your using. Be sure your feeding correctly, doing everything you can to reduce food waste, and use only high-quality foods. A good indication of being underfed is a concave belly; fish should have well-rounded bellies but not extraordinarily bulbous.

Past that, you can increase your tank maintenance or just add to your filtration capacity. This might be something like increasing the frequency at which you swap out your filter sock or maybe consider an automatic filter roller. Adding a protein skimmer, refugium, or algae scrubber to the aquarium is also a great approach to help reduce rising nitrates and phosphates.

10) Not Using A Clean-Up-Crew

Clean-up-crew or CUC for short is a population of invertebrates (snails, crabs, conches, urchins, etc.) and utilitarian fish (tangs and blennies) kept in your aquarium for the specific purpose of eating algae and scavenging the tank for leftover food and waste. These CUC animals are absolutely critical to your long-term success and are something you don't want to neglect or overlook.  


The advice is pretty simple, take advantage of clean-up-crew animals in your tank.  Be sure to also watch episode 39 of The Beginner's Guide which is all about using a clean-up-crew (CUC) in your saltwater aquarium which covers the topic in detail.