Hydroponic Reservoir

The reservoir is an essential component of any hydroponics system. As discussed in previous pages, hydroponics uses a nutrient solution (water and fertilizer mix) to provide nourishment and hydration to plants. Thus, a hydroponic reservoir is essentially the storage tank for the nutrient solution.  As we will discuss later, each hydroponic system uses a reservoir in a slightly different manner. We will then profile some of the best hydroponic reservoirs to choose from.

Do you really need to use a hydroponic reservoir?

You will need to store the nutrient solution somewhere…so yes. If you are looking for a complete kit instead of piecing together components for your own DIY hydroponic system, consider purchasing a hydroponics system kit (see our Hydroponics System page for recommendations). These kits come complete with a hydroponic reservoir, plus everything else you need to start growing.

Determining the Correct Size of a Hydroponic Reservoir

➤ Bigger is Better

Hydroponic growers often encounter problems because their reservoir is too small to accommodate the plant’s needs. Oxygen depletion, pH swings, and fluctuations in nutrient solution can all be adverse effects of a small hydroponic reservoir. Therefore, it is best to err on the side of caution and use a larger reservoir (i.e., more gallons).

Environmental factors can also play a role in how much nutrient solution your plants will need. Most plants have an ideal humidity level of between 60 and 80 percent. Anything below 40 to 50 percent will cause plants to require significantly more water volume per plant. As temperature and light levels increase, plants will also require more nutrient solution to maintain their health. So consider these factors when choosing an adequate size for your hydroponic reservoir.

➤  The Minimum Gallon Rule

At the very minimum, small plants should receive at least ½ gallon per plant. Medium-size plants should receive at least 1 to 1 ½ gallons per plant, while large plants should receive 2 ½ gallons as a minimum. Many hydroponic growers prefer doubling these number as their starting point, thus increasing their likelihood of success.  As we said before, bigger is better!

A Few Other Considerations


Keeping a lid over the hydroponic reservoir will help reduce evaporation, algae, pests, and contamination issues.

Water temperature

Temperatures inside the hydroponic reservoir should be maintained in the 65-75-degree range. Smaller reservoirs are more susceptible to temperature fluctuations. A water heater may be added, if necessary.


Remember to periodically clean your hydroponic reservoir. This will lessen the chances of mold. pests, and other issues.

Extra reservoir

Some growers use a hydroponics barrel or a convert tank as an extra reservoir. These keep an easy-to-access supply of fresh water nearby. Extra hydroponic reservoirs may be especially helpful to growers who use tap water, as water left standing for a duration of time helps to reduce chlorine and other chemicals, as well as bring water to room temperature and pH-neutrality.

How Different Systems use Hydroponic Reservoirs

Deep Water Culture (DWC)

DWC is a method of hydroponics whereby plant roots are suspended within the hydroponic reservoir which holds an oxygenated nutrient solution.

Drip System

The hydroponic reservoir in a drip system – or top feed system – usually sits below the plants. A pump brings the nutrient solution above the plants, then uses emitters to drip the nutrients into the root zone. Once the solution cycles through the growing medium, the excess drains back into the hydroponic reservoir to repeat the process.

Ebb and Flow

Ebb and Flow – or Flood and Drain – is a system in hydroponics whereby the reservoir is positioned underneath the grow tray holding the plants. The nutrient solution is periodically flooded into the grow beds, then drains back into the hydroponic reservoir. This process normally utilizes a timer for interval flooding.

Nutrient Film Technique (NFT)

NFT techniques constantly pump a thin film of nutrient solution through tubes or channels. The roots of the plant are suspected in these channels and nourished by this constant flow of the nutrient solution. The hydroponic reservoir can be situated anywhere so long as the water pump can access it and the nutrient solution can return to the reservoir.

Wick System

The wick system is the most basic of all hydroponic systems. The hydroponic reservoir stores the nutrient solution, and a fabric-type of material wicks the solution from the reservoir up into the grow medium. This keeps the plant’s roots continuously moist and nourished.

Best Hydroponic Reservoir Options

Now that we have covered the basics of what a hydroponic reservoir is and how it functions, let’s now review some of the most popular and best options for your particular hydroponic system design.

Price Range – $

General Hydroponics 4-Gallon WaterFarm Reservoir

Dimensions: 9.6” x 9.8” x 12.6”

Check Price

General Hydroponics reservoir is designed for their popular WaterFarm growing system. This 4-gallon unit can be used as a replacement reservoir for a WaterFarm system. It can also be a starting point to a DIY hydroponics setup and then adding additional components to complete the system. The versatile General Hydroponics WaterFarm Reservoir features a square design to allow hydroponic gardeners modules packing and easy storage.

Who is this perfect for?

The WaterFarm Reservoir is good for hydroponic beginners. However – at just 4-gallons – this hydroponic reservoir is not adequate to supply more than just a few smaller plants with their nutrient solution. With that said, the WaterFarm series allows you to add additional modules as needed, so adding more reservoirs would enable you to add more plants.

Pros :
Versatile reservoir bucket from General Hydroponics popular WaterFarm Series
Can be used as a replacement, or as a reservoir in a DIY system

Cons :
A small, 4-gallon reservoir limits the number of plants you can grow
No other components included (grow media, drip ring, pump, etc. are sold separately)

Tuff Stuff Products Oval Tank

 Available in 15, 18, 30, 40, 50, 85, and 140-gallon

Check Price

Tuff Stuff manufactures eco-friendly oval tubs for multiple uses. These 100% recycled LDPE plastic tanks are popular with hydroponics growers and are often used as hydroponic reservoirs. They are heavy-duty, impact-resistant, and have a rubber-like quality. Tuff Stuff manufactures their oval tanks in numerous sizes, including 15, 18, 30, 40, 50, 85, and 140-gallon.

Who is this perfect for?

These are high-quality and inexpensive hydroponic reservoir options. Anyone interested in designing their own system would appreciate the versatility Tuff Stuff affords. With 7 sizes to choose from, hydroponics growers should be able to find the correct size reservoir they need.

Pros :
Constructed with eco-friendly LDPE plastic
This versatile oval tub can be used in various hydroponics applications, including as a reservoir

Cons :
No lid

Price Range – $$

Active Aqua 25-Gallon Reservoir

Dimensions: 25-gallon – 30.75″ x 30.75″ x 13″

Check Price

Active Aqua manufactures some of the most popular reservoirs used in hydroponics. Made from durable, UV-resistant, ABS plastic, this 25-gallon reservoir has a low profile design to fit beneath flood tables or other hydroponics setups. These reservoirs feature thick walls, rounded corners for easy cleaning, multi-level drill access points, and gradation to accurately assess water levels. Other sizes of Active Aqua reservoirs include 50, 75, and 100-gallon.

Who is this perfect for?

This Active Aqua reservoir would be a great fit for anyone’s various hydroponic applications. The features, quality construction, and gallon size optionality make this a top pick.

Pros :
Quality construction and multiple features
Various sizes to choose from

Cons :
Reservoir cover sold separately

Rubbermaid Commercial Structural Foam Stock Tank

Available in 50, 70, 100, 150, and 300-gallons

Check Price

Rubbermaid stock tanks are a multipurpose structure that works well with hydroponic applications. As a hydroponic reservoir, the seamless, structural foam construction ensures it will hold up to anything you throw at it or throw into it. There are 5 sizes to accommodate your watering needs– 50, 70, 100, 150, and 300-gallons. Reinforced ribbing and stepped sidewalls provide stability and durability, and the over-sized drain plug allows for easy cleaning and draining. Made in the USA.

Who is this perfect for?

These stock tanks are versatile tools for any hydroponics grower. The various sizes available gives the grower plenty of options to choose from, and the quality of Rubbermaid ensures durability as a hydroponic reservoir.

Pros :
This multi-purpose stock tank can work as a hydroponic reservoir
Seamless and watertight construction

Cons :
Not food grade plastic and no lid

Flo-n-Gro 70-Gallon Reservoir


30 gallon measures 12.5” x 31” x 31

 70 gallon measures 12.5” x 46” x 46”

Check Price

Flo-n-Gro reservoirs & lids are constructed from premium ABS plastic. They are durable, UV-resistant, and crack-resistant. Flo-n-Gro products are adaptable and can be used as a water source for many different types of hydroponic setups.  The 2-piece lid is sold separately. A smaller, 30-gallon reservoir is also available for purchase.

Who is this perfect for?

The Flo-n-Gro reservoir is a fantastic option for larger-scale hydroponic growing. With a 70-gallon capacity, this model would work perfectly for hydroponic cannabis growers or any other high-volume hydroponic growers.

Pros :
 UV inhibiting and crack resistant ABS plastic construction
70-gallon hydroponic reservoir for larger-scale growing (30-gallon also available)

Cons :
✗ Lid sold separately

Price Range – $$$

General Hydroponics Controller with Master Reservoir

14.6” x 16.3” x 23.7”

Check Price

General Hydroponics’ Controller is simply a container with a float valve which is connected to the line of grow modules. The master reservoir situated on top of the Controller. When plants draw the nutrient solution from their individual reservoirs, the drop in liquid causes the float valve (in the Controller) to open.  This draws fresh nutrient solution from the master reservoir. This is a simple and reliable way to automatically maintain ideal nutrient levels in the system. Included is a 13-gallon reservoir, 8-gallon controller, float valve, tubing, and fittings.

Who is this perfect for?

The General Hydroponics Controller is designed to control 8 modules (but can accommodate 12 max), allowing for a decent amount of plants. It’s easy to operate and keeps plants well-fed. For someone who is looking for more output, the Texas Controller (also by General Hydroponics) may be more suited to those growers.

Pros :
Efficient hydroponics reservoir and control for simple and effective growing
Allows you to customize the hydroponics setup

Cons :
13-gallon reservoir may not be large enough for some indoor growers
Modules for plants sold separately

AutoPot FlexiTank Reservoir

Available in 25, 60, 105, 200, and 265-gallon

Check Price

The FlexiTank Reservoir is a practical water storage solution. It’s compact and collapsible and can be easily packed up into a closet when not in use. The FlexiTank requires no tools to assemble and can be used for a host of hydroponic reservoir needs. Available sizes include 25, 60, 105, 200, and 265-gallon tanks.

Who is this perfect for?

For anyone looking to make their life easier by having a supply of fresh water at their disposal – in any location – consider the FlexiTank by AutoPot.

Pros :
Multiple reservoir sizes to choose from
Easy to set up

Cons :
Leaks can occur if the material is punctured

Price Range – $$$$

Botanicare 40-Gallon Reservoir


10 gallon – 26.8” x 17.4” x 10”

20 gallon –  33.1” x 24.9” x 23.7”

40 gallon – 38.8” x 34.8” x 12.3”

Check Price

Botanicare makes top-of-the-line hydroponics reservoirs. They are made from BPA-free, recyclable materials (using solar energy) and designed for durability, performance, and easy maintenance. Botanicare’s premium reservoirs are low profile and easy draining and include bulkhead ports to accommodate an internal, submersible water pump or join multiple reservoirs (inline or side by side). Botanicare also manufactures 10-gallon and 20-gallon reservoirs.

Who is this perfect for?

If you want a top quality reservoir and don’t paying a little extra, nothing beats Botanicare.  

Pros :
Eco-friendly and made in the USA 
Versatile and high quality

Cons :
Lids sold separately

Superponics-8 Hydroponic System

Dimensions: 18” x 11” x 11”

Check Price

The Superponics-8 Hydroponics System is a fantastic hydroponic reservoir kit, especially for propagation and growing small plants like herbs. This unit fuses top-feed Drip and Deep Water Culture techniques to create a state of the art growing system. Superponics’ design features 8 planting sites, 132 GPH water pump, air pump and air stones, extra-long drain tubes, and a 3-year warranty. The reservoir is easy to clean and easy to operate.

Who is this perfect for?

This hydroponic reservoir is perfect for plant propagation and growing smaller plants. The kit saves you the time of buying each component separately, and it easy to use. Perfect for any hydroponics hobbyist – beginner to expert.

Pros :
✓ Easy to operate reservoir kit
3-year warranty

Cons :
Reservoir only large enough to hold roughly 4 gallons
Not made for larger plants

Thank you for reading our article on reservoirs for hydroponics. Feel free to browse our other pages, including Best LED Grow Lights, Hydroponic Trays, Hydroponic Growing Medium, and other useful hydroponics and aquaponics information and product reviews!