What You Need To Know About Hydroponic Reservoirs!

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What You Need To Know About Hydroponic Reservoirs!

Hydroponics can be a tricky endeavor for many to take on as the sun and soil won't be there to do the heavy lifting, leaving you with all the responsibility for your plants' growth. That's why crucial that you know when and how much water & nutrients you should add to your hydroponic solution. But it's also essential to know when to take them away. 

For hydroponic solutions, you can entirely change it when the volume of added top-off water equals the total volume of the tank, which happens around every two weeks or so. Doing this ensures no over-accumulation of nutrients, bacteria, and fungi. However, frequent changes may be necessary if you have trouble maintaining proper pH levels and electrical conductivity. 

At Trending Up, we specialize in providing top-notch lifestyle solutions at an affordable rate. One of our biggest sellers is our hydroponic growing systems, so we know all there is to know about the process. 

Due to our line of work, we often come across questions like "how often should you change hydroponic water and nutrient solution?" and "how often should I change my hydroponic reservoir?" So we thought we should take this opportunity to explain and answer all these burning questions about hydroponic reservoirs and gardening. 

In the following passages, you will find all you need to know about hydroponic reservoirs to ensure you face no trouble doing it at home. So without any further delay, let's begin!

How Often Should You Change The Water In A Hydroponic Reservoir?

Completely draining your hydroponic reservoir can sometimes seem like a burden, especially when you consider the time and money it may take. Still, it is necessary for maintaining the ever-so-delicate balance of nutrients in the hydroponic system. 

If you don't change it when needed, then the ratios will be thrown out of whack, and that will impact plants' growth as it can encourage the growth of harmful organisms. Also, it creates conditions where disease thrives, resulting in killing your plants. 

How Often To Change Hydroponic Nutrient Solution?

Several factors and stages go into determining when and how often you should change the nutrient solution in your hydroponic reservoir. Here in the following, those are the things we will talk about. So let's check them out!

Topping Off The Solution

Whenever you set up your hydroponic reservoir, you'll notice the water level reducing little by little. That happens due to evaporation and transpiration. Now, to tackle this loss, you will need to periodically add more water to the reservoir to ensure the volume remains the same. 

Gradually adding water to maintain the level is known as "topping off," and the reason it's vital is that nutrients like nitrogen, copper, and zinc don't exit the solution as quickly as water does. So that means it can become too concentrated for the plants, which can harm the plants, especially the roots. 

So now the question remains, "how often should you be topping off?" Well, a good rule of thumb is to top off the solution every 2-3 days, but you can even do it every day if you like. The main factor here is measuring how much water you are adding when you top off. 

When Should You Fully Change The Solution Of A Hydroponic Reservoir?

Once you've topped off the same as the maximum volume in your reservoir, you'll need to change the entire solution. So if you have a 5-Liter pool and are adding 500mL of water every day, you will need to do a complete change every ten days. For a 20L reservoir, if you add 1L of water each day, you can wait 20 days before changing the entire solution. 

So the ballpark number for doing a complete change is at around two weeks or between 10-20 days. Hydroponic gardening is a brilliant way to grow plants, but you have to remember that it's more science than art, so precision matters a lot. 

Maintaining The Perfect pH.

pH is the concentration of hydrogen ions, or acidity, in a given solution. If you hate chemistry or think it's a complex concept to understand, don't worry. 

We won't get into the scientific side of it. Instead, we will focus on understanding the role pH plays in a hydroponic system, and that's pretty easy to understand. pH doesn't directly impact your plant's growth. 

However, they do affect how well your plants absorb the nutrients in the reservoir. So if your pH levels aren't at optimum levels, then the roots won't properly absorb all those tasty nutrients that encourage better growth. The ideal pH count is usually between 5.5-6.5 but varies from plant to plant. 

So make sure you know the optimum pH level of the plant you are looking to grow in a hydroponic reservoir. Here is a table showcasing the optimum pH levels of the most popular plants for hydroponic gardens to further assist you in the matter!


Ideal pH Range


6.5 - 7.0


6.5 - 6.8


6.0 - 6.5


6.0 - 6.5


6.5 - 7.5


6.5 - 6.8


6.0 - 6.5


6.0 - 6.5


6.5 - 7.0


5.5 - 6.5


5.5 - 6.5

Peppers, Chilies, & Jalapenos

6.0 - 6.8


6.0 - 8.0


5.8 - 6.0


5.8 - 6.4

How Do You Measure pH Levels?

Measuring the pH levels is straightforward. You can find pH test sticks in your local hydroponic store. You can even find them at pool and aquarium supply stores or online. 

Once you get the sticks, dip them in the water, see them change color, and then check the back of the box to see what pH this corresponds to. We recommend you do a daily pH check to ensure the solution is at its optimum levels. 

How To Manage pH In A Hydroponic Reservoir?

Now, you can expect slight changes in pH levels in-between solution changes. Usually, it starts in the lower end of the range and gradually rises. 

If you see that the pH level is getting higher than you want it to be, you can either use commercial "pH up" or "pH down" products or use products like vinegar that you will find in your home to adjust the levels. 

To ensure optimal growth, you will need to maintain the pH levels as you do with the water level in your hydroponic reservoir. But it would be best if you also kept in mind that modifying the reservoir water by adding pH-altering products isn't a good solution for the long term. 

It's a quick fix and doesn't last long at all. So you'll be facing the same problem very soon. However, completely changing the reservoir solution will entirely solve the problem. 

If you see that the pH level is consistently out of the acceptable range even after using the additives, then it's high time you change the water in the hydroponic system. Now, it's impossible to predict how the pH levels will change over time entirely but if you see this problem happening frequently, then change the water.

One thing of note is that regular water has a pH of 7, which is what you should target, but your tap water or garden hose water may be more or less acidic, so use a test kit to check the pH levels before adding them to your solution. 

Conductivity Tests

Conductivity test is another important factor you need to know about when getting into hydroponic gardening. The conductivity test checks out your solution's electrical conductivity (EC). Its a measure of how well your solution can conduct an electric current. 

Now, you don't need to go into the rabbit hole of chemistry and understand why you need it. However, you need to know that the higher the conductivity, the better your nutrient concentration is. 

So, before you add your solution to the hydroponic reservoir, make sure you check out its EC using a conductivity meter which you can find in your local hydroponic supply store for around 15-20 bucks. 

The goal is to keep the EC consistent from the first time to the last time you add the solution throughout the growing process. Remember, very high nutrient concentration in the solution will cause root problems, and too little will leave the plants undernourished. 

Like pH levels, you can alter the EC reading simply by adding nutrients or diluting with water. But if you notice that there are consistent problems with your EC reading even with the adjustments, you will need to change the hydroponic nutrient solution entirely.

If you've just started hydroponic gardening, then we recommend you do regular EC tests to ensure your nutrient solution is optimal. 

Some Other Factors For Changing The Hydroponic Solution

Some Other Factors For Changing The Hydroponic Solution - hydroponic reservoir - Trending Up

So now that we are done with the primary reasons for changing your hydroponic nutrient solution, we thought we should cover some other reasons too. That way, you can dive into hydroponic gardening without any worry. So let's check out those factors:

  • If you are making significant changes to your nutrient ratios, you'll need to flush out your tank and start with a new solution from scratch.
  • Be on the lookout for visible signs and symptoms of unhealthy nutrient imbalances and/or bacterial growth. Here are some symptoms you should be on the lookout for
  • The yellowing of your plant's leaves is known as chlorosis.
  • Purplish tint appears throughout your plant, conveniently known as "purpling."
  • Necrosis, or death, of sections of leaf or roots.
  • Stunting. It's where a specific part of your plant is growing at a much slower rate than others or if the plant itself is experiencing delayed growth, you should look to change the total solution. 

    How Long Do The Nutrients Last In A Hydroponic Reservoir?

    The nutrients in your hydroponic reservoir will usually last around 7 - 10 days if you drain, clean, & remix your nutrients, and top off the system with plain water daily. Keep in mind that the nutrient strength will keep diminishing as plants absorb the nutrients in the system. 

    Can You Create A Hydroponic System Without Nutrients?

    Yes, you can, but you should know that plain water doesn't have sufficient nutrients for proper plant growth. The most significant advantage of hydroponic systems is that you don't have to rely on soil for providing plant nutrients. With a hydroponic growing system, you can precisely control the balance of nutrients your plants receive.

    What To Do With The Used Up Hydroponic Solutions?

    Making and balancing your hydroponic solution is much work, and, understandably, you feel disappointed that you need to throw it out once it becomes unusable for your hydroponic system. Well, you don't have to throw it out. You can mix it with a 50/50 ratio with tap water and give it to your flowerbed or outside garden, and your plants will love it! 

    However, if you don't have an outdoor garden, dispose of the wastewater down the drain. Do not dump it outside as it can flow into a creek or other water source and easily unbalance the nitrogen ratios of that ecosystem and damage the species living there. 

    Are Hydroponically Grown Foods Good For You?

    Yes, they can be as good as traditionally grown food, but it depends on whether or not you nail nutrient balances. We already know which nutrients make traditionally grown foods nutritious, so if you can ensure your nutrient solution has the correct ratio of elements, then you can have delicious, highly healthy harvests from your hydroponic system. 

    In addition, with hydroponically grown food, you can ensure your plants are without pesticides and other potentially harmful chemicals that outdoor plants may be exposed to.

    Finding The Right Hydroponic Growing System

    So there you go, those are the things that you need to know about hydroponic gardening systems. Hopefully, by now, you know how often you should change the water and nutrient solution in a hydroponic reservoir and other essential aspects of a hydroponic garden. All that's left right now is to find the right hydroponic growing system, and that's where Trending Up can help you. 

    Our curated list of hydroponic growing systems will make gardening easy and ensure you can quickly take care of your plants. So contact us, and we will hook you up with one. 

    Also, if you have any more questions about hydroponic gardening or systems, feel free to drop them in the comments below or hit us up on our socials, and we will answer them all for you. And with that being said, that's about all we have for you now. We will come back with something new for you soon. Until then, see ya!