How to Safely Raise the pH in an Aquarium


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Successfully maintaining your aquarium water pH should be enough to qualify anyone for some sort of aqua-science degree. Instead, you get the benefit of watching your fish stay healthy and vibrant. In all seriousness though, tank management is tough stuff sometimes. Raising your pH, lowering your pH, and the basic attempt to maintain a consistent pH imbalance is an ongoing process. However, trying to understand why your water chemistry is waxing and waning can be super frustrating. 

Here is the thing – mild fluctuations in your pH balance are normal. There are so many factors that can affect water chemistry –pH being the biggest. Tank size, fish species, and the variety of species such as amphibians, crustaceans, and/or plants can play a role in pH levels. It is helpful to identify the various reasons why your pH might be dipping and how to safely raise it without harming livestock.

pH Levels: What Do They Mean Exactly? 

If you were lucky enough to have a cool science kit or have some classes in school, you probably have seen the rainbow-looking color chart that they always come standard with. The pH testing strips or pH color-wheel interpret the amount of acid or base present in a substance or solution. The exact definition specifies that the term pH refers to the number of hydrogen ions and hydroxide ions present in solution or liquid such as in the case of your tank water. 

-The lower the number of hydrogen ions present, the more acidic the water, liquid, or substance. On the color chart, the more acidic the water is. 

-The higher the number of hydrogen ions present, the more basic the water, liquid, or substance. On the color chart, the more basic or alkaline the water is. 

Understanding How pH Levels Can Impact Fish Health

Fish aquariums are designed to mimic their natural environment – it is a recreation of a natural water ecological system. The more you can do to maintain the ideal pH balance of a fish’s natural habitat, the healthier they will be. The pH levels along with other water components work symbiotically together and when they are off, the aquarium inhabitants react in unfavorable ways.

In a natural water environment, pH levels that are too low cause fish to leave the area. When they are a part of a closed system, they can’t escape and fish death is likely to occur. High acid levels in your aquarium can harm the skin of the fish especially if they are young or especially sensitive. It can also inhibit growth and compromise fish reproduction efforts. 

The ideal pH range should be specific to the fish species housed in your tank. The goal is to have a neutral tank balance (pH level 7). Experts cite that freshwater fish thrive best in ranges about 6.3 – 7.2, while saltwater fish thrive best in a slightly higher range of 8.0 -8.4

What Causes pH Levels to Suddenly Plummet? 

Nothing can be more of a head-scratching moment to test and find your pH levels have dropped dramatically seemingly without rhyme or reason. Well, there were probably some reasons – let’s talk about them. 

Too many fish. Did you go a little crazy at the fish store?  Overstocked tanks are a common culprit. In most cases, fish are highly adaptive. However, it is always a good idea to do some research into the species and ideal living conditions. 

Overfeeding. Nobody likes skinny fish – we get it. BUT, overfeeding your fish leads to an abundance of non-digested waste in your tank. This in turn leads to toxic levels of ammonia. 

Tank under-cycling. When you get a new tank, the first thing you have to do is cycle your water. This requires a hefty amount of patience. What ends up happening is that you add stock to your aquarium before the water has had enough cycling time. This is important because cycling equates to nitrification. In closed systems, aeration is a huge component. It helps convert ammonia into less toxic nitrogen compounds. This also tends to happen following a full water change. 

A dirty tank. Aside from the testing and monitoring process, tank maintenance is your other best bet to keep pH levels in check. It helps to reduce the amount of free-floating decay and waste matter from clouding your tank and also assists with ideal water chemistry overall. The key here is to assign proper filtration methods and tank cleaning strategies. As we mentioned above, an under-cycled tank can equally cause problems so make sure your water changes are conducted with best practices in mind. 

Water source. Choosing to refill your tank water with ordinary tap water could present some real problems. Again, we can’t stress testing enough for water sources of any kind. Pure water exhibits a pH of 7. This represents a neutral pH level. However, in some cases, adding water can dramatically alter the pH of your tank so test it before, during, and after. Popular choices for topping off water include distilled water. If you have a salt-water aquarium, purchasing seawater versus premixing saltwater works well too. 

Decaying fish. Unfortunately, fish death does happen from time to time. The causes may vary, but if you don’t catch them, they can sink into the aquarium substrate sight unseen. The natural decay process of the dead fish can upset the pH balance very easily. 

Contaminated or sick fish. Getting your cool new fish in your tank is beyond exciting, BUT try and hold off a bit and put your new baby in quarantine. This prevents a lot of problems. Many times when you buy a fish fresh from a stock tank from the store or other source, they harbor biologics unique to the tank they were in. Adapting to a new aquarium takes some time and it can save you money in the long run. A sick fish can spread disease and wipe out your whole tank and in the process disrupt your water ecology i.e. pH balance.

Aquarium gravel/substrate. In some rare cases, the gravel or rock can throw off the tank chemistry. It isn’t always obvious, but they can disguise and harbor waste materials that encourage the production of bacteria creating excess amounts of ammonia. 

How to Properly Test Aquarium pH Levels

Experts suggest pouring out the water into a separate container, allowing it to aerate with a circulation stone, and then testing it a day or two later. The reason being is that the true pH can be inhibited by CO2 levels causing pH levels to spike downward. You don’t want to prematurely add buffering agents to your tank. This could further complicate your imbalance. 

Another best practice is to keep a journal or record of pH dips and spikes via a constant monitoring device. They integrate flawlessly with today’s technology making it a super simple process. For this, we recommend using an electronic pH probe type sensor because they are significantly more accurate than most litmus paper pH kits found in pet or pool stores. 

These types of sensors are designed to stay immersed indefinitely for continual monitoring. For the win, they aren’t that much more expensive and some even are designed to read for temperature and other components. 

Safely Raising pH Levels When the pH Drops

We get it – your baby clownfish is your prized possession and you will do ANYTHING to keep that little guy happy and healthy. Consequently, when the water pH dips it can set off a panic like no other. (For us fish crazy people.) Don’t worry. It will be okay. Here’s what to do: 

-Check again to make sure you have the true pH reading. (Read above for reference.)

-Don’t be tempted to use over-the- counter remedies to buffer your tank i.e. vinegar, baking soda

-Check your aeration device. In very large tanks, a more powerful device is needed. For best results, check your DO(dissolved oxygen) levels and read about how DO  influences water quality.  

-Clean your decoration and gravel. Calcium carbonate can act as a natural buffer in some instances. Additionally, tank decoration is an excellent growing medium for waste matter and foreign bacteria which influences pH levels dramatically. 

-Use safe buffering agents to add to your tank. Why chance it? Use a product you know won’t magnify your water chemistry issues. For best results, use as indicated and perhaps test after each addition throughout the day in various locations within the tank. 

What Routine Maintenance is Needed to Mitigate pH Problems

Many Aquarium hobbyists will be quick to pull you aside and tell you the key to maintaining a beautiful tank with minimal issues is to go bigger. While many would think you are creating more work for yourself, it is the opposite. Smaller tanks are known to have highly sensitive water chemistry because it is difficult to recreate the diversity seen in large volume natural aquariums. 

That being said and regardless of tank size, your routine should consist of continuous monitoring, testing, and water changes. The types of tests you need to perform will be similar in just about any kind of aquarium setup (saltwater or fresh). 

Here is a list of routine tests and duties you will have to perform to keep your fish healthy and water clear:

  • You will have to perform partial water changes due to evaporation about 2x per month depending on tank size and location. On average topping off about 25% of your tank water is advised. Be sure to test your water before adding it and allow for proper cycling. 
  • Clean gravel and filtration mediums. This may require using a gravel vacuum to sweep the ickies away easily so to speak. 
  • Changing the filter is also a good idea and checking the filter medium at the same time you top off the water – about once a month depending on aquarium size and stock volume. 
  • Testing requirements for various water components on a routine basis:

pH: Daily testing for new aquarium setups is a good idea. Purchasing good pH monitoring equipment is the key here. As mentioned above, they interface well with modern technology and can handle just about any size setup. Downloadable charts for ideal pH per fish species are easy to find. We can’t emphasize enough doing a healthy amount of due diligence (research) and also study best practices to help maintain a good ecological balance.

Temperature: Most freshwater fish have a preferred temperature of about 76°F and 80°F. Truth be told, you will find that many aquarium stores sell stick-on type temperature devices, but you may be better off with an all-in-one type of temperature probe. They measure multiple readings for pH, temperature, and alkalinity. The problem with stick-on temperature devices is they don’t account for cold or warm water pockets. Water circulation plays a big factor in temperature and pH. 

Salinity: If you are outfitted with a saltwater tank, checking the salinity often is a good idea especially if you just topped off the water. It seems like topping the water would dilute the amount of salt in your tank, when in fact it is just the opposite. The salt settles at the bottom in aquarium medium so when you add water it complexes in with the water and brings it back into circulation. 

Ammonia, Nitrites, and Nitrates: Testing equipment is essential for these elements and the levels of each can provide a lot of clues as to why your pH may be off. Observation and visual inspection go a long way to identifying issues. You will want to look for fish with red streaks in or around the gill area, fish swimming near the surface, and/or sick-looking fish which typically indicates excess ammonia. BTW: Fish that are laying on the bottom without moving is like placing a 911 call for a water chemistry issue. 

Alkalinity: Total alkalinity is tested by water sampling and a specialized device. For saltwater and reef aquariums, this is one of the most important water measurements. Ideally, the alkalinity for saltwater should be about 142-215ppm. Maintaining ideal alkalinity levels in reef and salt aquariums is vital for overall coral health and prevents pH swings. 

Sourcing Aquarium Testing Equipment and Advice

Atlas Scientific understands how important your investment is to you. Aquariums add peace and tranquility to any space. While beautiful, they do take time and some know-how to keep them that way. Maintaining the water pH is a major contributor to that beauty. Our pH, temperature, and DO sensors and probes are designed for any size set up and can make easy work out of a complicated process. Feel free to reach out to one of our team members here

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