Best Hydroponic Reservoirs [+ DIY Tank Guide]

Look around a while and you’ll hear the same thing – “the hydroponic nutrient tank is the heart of the system.”

While we argue that the circulation pump serves as a better example of a heart, the nutrient tank is indeed a vital component.  Whether you call it a tank or a reservoir, you are going to need one to hold all of the nutrient solution you intend to deliver to your hydroponic garden.

You can find pre-molded hydroponic reservoirs that are manufactured specifically for the job. This option will cost you a little more than the DIY route, but can be preferable to those gardeners that want an immediate and presentable setup. 

Botanicare 707135 reservoir, 20 Gallon

These nutrient tanks are molded in such a way that you can easily mount them in specially-built tray stands. Paying attention to what you’re getting can result in a modular system that is easy to re-position. This makes it easy to move your garden’s location or even change hydroponic gardening methods without buying any new equipment!

Fast Fit 706121 Tray Stand, 3′ x 3′

By combining this nutrient reservoir with the hydroponic garden table one could easily grow between 9-12 plants, depending on the species.

Setting up multiple tables inside a greenhouse or LED grow room could quickly become a successful commercial operation, if the gardener were so inclined. Likewise, one table could easily sit in the corner of a garage, greenhouse, or even office if the hydroponic gardening hobbyist was looking for an easy to install setup. 

What is a Hydroponic Reservoir Tank?

At its core, a hydroponic nutrient reservoir is simply a watertight vessel for holding your mixed solution until it is delivered to your plants. If your plants were in soil, you would simply moisten the substrate (the dirt) with your mixed solution. 

Hydroponic gardeners, however, are trying to maximize their plants’ growth. 

The science has been so thoroughly discussed that it is now common knowledge amongst gardeners and horticulturists alike that hydroponic gardens offer quicker growth and larger yields over soil. It is generally the startup costs that deter the would-be hydroponic farmer from reaping the benefits of a hydroponically grown crop.

Buy vs. DIY

Depending on the garden you want and your own mechanical aptitude (or that of friends that you trust!), buying the components and assembling them into a functioning hydroponic garden might be the better option. Everything fits together, and if you feel lost there’s always the “1-800” number you can call.

However, if the costs are the only thing holding you back from trying hydroponic gardening, then you really need to keep reading. We are going to break down how to prepare your own nutrient tank out of materials most people have laying around or can find for cheap or even free!

Let’s quickly examine some of the benefits associated with buying compared to doing it yourself:

Buying Pre-Built Reservoirs vs. Building a DIY Nutrient Tank

If it’s starting to look like buying is the right choice for you, you’re not alone!

There has been an explosion in hydroponic gardening interest over the last few years, and several companies have emerged to offer quality products at competitive prices. If you’re looking for a particular shape, size, or kind of hydroponic nutrient reservoir, check out Hydrobuilder.

They are a company out of northern California that has been a dominant supplier of hydroponic components since 2011, and probably have the widest variety of in-stock selections available domestically.

If you would rather save the $$$ and build your own, we understand completely. Read on and learn how to build your own nutrient tank and save the money for other parts of the system.

How Hydroponic Reservoirs Work

The reservoir, or “tank”, is essentially the primary component of any hydroponic gardening system. Maybe the nutrients are the really important part, but without a good, well-connected tank, you would lose too much nutrient solution to leaks, evaporation, and contamination. 

How the reservoir connects to and interacts with the rest of the system varies significantly, depending mostly on the general design of your system. Here we will take a brief look at the most common hydroponic gardening methods and examine how the reservoir interacts with the other nutrient delivery components.

For an interesting reservoir system check out the dutch bucket method.

Ebb and Flow

Ebb and Flow systems are also sometimes referred to as “Flood and Drain” systems. Most commonly this system will consist of two tanks located closely (usually the reservoir is beside or directly under the plant bed). Electric pumps transfer nutrient solution from the reservoir to the plant bed, bringing the bed’s level up to the plant roots. The system then slowly drains back down to the reservoir, allowing it to be recycled and reused. The reservoir can be adjacent if pumps are used and you have good tubing and good flow. Otherwise it’s better to place the reservoir under the beds and let gravity help out with drainage..

Nutrient Film Technique (NFT) 

In the Nutrient Film Technique (NFT), the plant beds are most often placed in a straight line (such as in a piece of PVC pipe or plastic handrail) or in an “S” shape mounted to a wall or A-Frame. Nutrient solution is circulated in a fashion similar to ebb and flow, but instead of a flooding and subsequent draining, the solution is allowed to flow in a stream at a level that just touches the root tips. The movement of the nutrient solution causes naturally occurring mist inside the plant bed, coating the exposed roots in a film of nutrient rich liquid that drips back down the roots. This allows for optimal nutrient and oxygen absorption by the roots. The reservoir can be located anywhere that is convenient to access and pipe in.

Deep Water Culture (DWC) 

Deep Water Culture can be one of the most economical methods, commonly achieved using two 5-gallon buckets and an airstone. The bottom bucket is the reservoir, while the top bucket holds the plant. The roots hang down into the solution while the airstone provides the necessary aeration for the oxygen the roots need. While any plants can be grown using this method, it is common to see larger bushes, trees, and herbs grown this way.

Drip 

It is also common to place the reservoir underneath the plant bed in a drip system. In this system, nutrient solution is carried to the grow medium via tubing and allowed to saturate the medium (rockwool, perlite, etc.) and drip down the roots. The solution then drips into a collector that returns it to the reservoir. Side Note: The build in the video above can easily be made into an aeroponics system by using a smaller diameter nozzle to create a mist in the tank.

Wick 

Wick systems require the reservoir to be directly under the plant bed, as they rely on a wicking material (usually wood or cord) to transfer nutrient solution up to the growing medium. This keeps the medium at a natural saturation level that is neither too little or too much. A very low-maintenance setup.

How Big Should my Hydroponic Reservoir Be?

The first things that you’ll want to consider (and you do need to consider them together) are the type of plants you want to grow, the number of them you want to grow, and their maximum size at maturity. 

Pro Tip: You may want to add a little extra (.5” each side) to the mature size, as hydroponics is famous for producing larger plants with fuller yields.

The next thing you’ll want to consider is how much solution you need to be able to hold in your reservoir.

A loose “rule-of-thumb” that you can use to ensure you have the water you need is to provide:

A minimum of 2.5 gallons for each large plant

A minimum of 1.5 gallons for each medium plant

A minimum of .5 gallon for each small plant

Count up your plants, add together the requirements, and you now know how large a vessel you need for your reservoir.

For Example:

Please keep in mind that this is following a general rule that provides bare minimum requirements. It is OK to go over on your nutrient capacity, and is actually encouraged whenever possible. 

Horticulturists at the University of Georgia spent quite a bit of time studying how plants consume water and how much water they need to survive as well as thrive.

Also bear in mind that large plants will require significantly more room to grow properly – check your vertical and horizontal clearances and research the species before you grow yourself into a bind!

You will find that some system designs allow for a central reservoir to easily be used with a manifold that feeds several garden beds from one large tank, but in our experience it is better in the long run to provide an individual reservoir for each plant bed.

As your experience, garden, and needs grow, you will start wanting to plant different things at the same time. This means each bed could need a different nutrient mix for optimal growth.

Dedicating a reservoir to each hydroponic grow bed early on allows you to always have the flexibility to make desired adjustments directly to that bed’s nutrients. 

How Do I Build a Hydroponic Reservoir?

Ah, the moment we’ve been waiting for! Just how do we build a reliable nutrient reservoir right here at home?

Building your own hydroponic reservoir is a simple, straightforward task. 

It may be the most essential part of a hydroponic system, yet it can also be the most basic. It really is just a tank, after all.

The most important criteria is that it is watertight. Plastic containers are a popular choice among beginners and advanced growers alike and are available in a variety of industry-standard sizes and shapes. 

If you have the budget for it, purchasing accessory components from a hydroponic supplier can offer peace-of-mind as well as tech-support. Buying a $10 bag of bulkhead fittings from a hydroponic supplier like Blumat or even Grainger or Fastenal justifies you calling and asking questions, should they arise.

Here are a few ideas:

• Re-use old fish tanks – just leak test first and keep in a safe location once installed
• Plastic storage totes (make sure they are deep enough to provide the volume you need)
• Large diameter PVC pipe (A 6’ section of 10” PVC pipe holds almost 25 gallons – and weighs 204 lbs. so a good stand is required)
• Plastic trash cans – 30 gallon is a standard kitchen trash can
• Those big blue plastic drums I’ve always heard called “pickle barrels” are around 50-55 gallons
• Avoid using metal, as the minerals will speed up oxidation (rust). Yes, aluminum and stainless steel will oxidize too.

Pro Tip: Once you’ve found your perfect reservoir, you need to make sure it is clean. Even if it’s brand new it could have oils from the mfg. process, so disinfect and clean every nook and cranny thoroughly. You can use a 50/50 solution of vinegar and water if chemicals are a concern (rinse at least 3 times with clean water, no matter what you use)

After you’ve made sure your new hydroponic nutrient tank is clean, you’ll need to leak test it. To do this, place it somewhere like a patio or in your backyard where it won’t damage anything if the worst should happen. 

Fill your reservoir more than you would fill it with nutrients; all the way if possible, and leave overnight. Ideally you can place it somewhere where it will be evident that it has leaked, such as on dry concrete or wood. If it is on a slight slope, the better, as leaking water will run – making it easier to see. 

If your tank’s exterior is dry the next morning, congratulations! You now have a reservoir. 

Now…to get the liquid from the reservoir to the plants…

Extra Components You May Need for Your Tank

Your new hydroponic reservoir may be the most important component in your setup, but by itself it is just a tote (or trash can, or whatever).

You are going to need a few attachments to make things work properly, and what you need will vary depending on the hydroponic gardening method you’ve settled on.

Hydroponic Nutrient Solution

If the reservoir is the most important part of your hydroponic garden, then nutrients are in second place arguing for a recount. Without good nutrients, you may be able to keep your plants alive, but survive is all they will do. If you are unsure about which nutrients you should be looking at, check out our 2020 hydroponic nutrient guide.

Hoses & Tubing

Tubing might seem simple, but tubes and hoses are the “veins” of your hydroponic garden, carrying the precious nutrient solution where it needs to go – your plants! 

Most hydroponic builds will recommend which type of tubing to use in a given application, but if you’re having trouble start with sections of a regular garden hose and 3/16” aquarium tubing (8mm).

It is important that you use opaque tubing whenever you can, as sunlight can stimulate the growth of certain algaes that can leech off of your nutrients. If you only have clear tubing available, simply use a 1” or similar diameter pvc pipe as a conduit. Simply thread the tubing through the pvc and use strapping to mount the pvc wherever works for your space.

Best Hydroponic Tubing

Hydro Flow 100 ft Vinyl Tubing, Black – 3/16″ ID x 1/4″ OD

The Fittings

By “fittings,” I mean all of the little elbows and tees that you use to connect all of your piping (to be clear, all tubing, hoses, and pipe falls under piping). It’s difficult to say how many of each piece you will need, or which pieces at all, for that matter! This is due to the fact that every build is different, essentially, and the materials required will vary depending on factors like the hydroponic growing method, the size, weight, and number of the plants being grown, and the location of both the grow bed and nutrient tank. 

One way to get an idea is to sketch out your build first. It doesn’t have to be pretty, just lines and symbols, with numbers for measurements and diameters. If you have the budget for it, I suggest getting more than you need of everything – and returning any leftovers after you’re up and running. Think of how many times a plumber goes to his truck…you’ll make twice as many trips back and forth to the store.

Fittings are inexpensive and are commonly sold in bags of 10 or 25. For your tank alone, you will want 2 bulkhead fittings that penetrate the tank wall as well as what you need to connect to your pumps. If you should have any leftover, hang on to them in case one begins leaking or you decide to tweak the system a bit.

The Pumps

You will employ two different kinds of pump in your hydroponic garden at one point or another. The first is the water pump, for the circulation or transfer of nutrient solution throughout the hydroponic garden. The second is the air pump, which pushes air through an airstone or any other attachment you connect to it. 

The circulation pump is the heart of the hydroponic garden, as it pulls nutrient solution from your reservoir and pushes it to your plants. Modern electric pumps are quiet and zero-maintenance. They are fairly simple to install and to automate – a feature you will likely consider the more complex your garden becomes. Air pumps can be very cheap (under $20) and are the exact same ones you use in a fish tank for bubbles. Those bubbles aerate whatever liquid they are in, causing oxygen molecules to be released. This is a requirement for some hydroponic growing methods, but we recommend aerating all reservoir tanks whenever possible to avoid stagnation.

Choosing the right pump is important. There are economy pumps out there if you’re on a budget – but our advice is that this is an area you want to invest in, not cut corners. You can save money on the nutrient tank, on the hoses and tubing – you can save money by going with a different build or even different plants. 

Best Water Pump

Active Aqua Submersible Water Pump, 1110 GPH

Best Air Pump

VIVOHOME Electromagnetic Commercial Air Pump, 20W/32W/50W/102W, 317/950/1110/1750 GPH, 6 Outlets for Fish Tank and Hydroponic Systems

The Airstone

Airstones will connect to your air pump via standard aquarium tubing and produce millions of beautiful bubbles once powered. Those bubbles provide aeration in your solution, which accomplishes a few things. First, they release oxygen into the solution, something all plants need. Second, the aeration prevents the solution from becoming stagnant and allowing mildew, fungii, and algaes to develop. Lastly, airstones can be placed directly in the solution in several of the hydroponic growing techniques in a way that allows the popping bubbles to create a fine, constant mist. This is approaching a back-door into aeroponics, technically speaking (but that’s splitting hairs). 

Airstones and air pumps are the one place we recommend using clear tubing. 

What Temperature Should My Hydroponic Reservoir Be?

At its most basic level, the warmer a solution is, the less oxygen it can provide a plant. 

Ideally, hydroponic solution should be kept at 65℉ to 68℉ for optimal nutrient and oxygen uptake, though temperatures as warm as 85℉ can allow for healthy growth in some species.

Most professional and commercial hydroponic gardeners utilize chillers in their systems. This is owed to the fact that the solution absorbs heat from numerous sources, including circulation pumps, led grow lights, and climate controlled environments. Chillers will most often be rated by horsepower (HP) and their flow rate, which will usually be provided in gallons per hour (GPH) or liter per hour (L/hr).

By contrast, if you have an outdoor greenhouse running hydroponic garden beds in a colder climate, you may need to install heaters. Water heaters are rated in Watts (W) and the ones used in hydroponic systems are just bigger versions of the submersible aquarium heaters in common use.

You can find a great reference here that breaks down when you need a chiller(or heater), and what size to get.

How Do You Keep a Hydroponic Reservoir Clean?

Sooner or later, people occur upon the question, “Will I need to clean my nutrient tank?”

Yes. Yes, you absolutely should. Over time, other forms of life will discover your hotbed of nutrition – forms of life such as algae, bacteria, molds, and fungi. Not only are these lifeforms potentially dangerous to human health, but they can be absolutely fatal to your entire garden. Root rot is real, and it sucks. 

The easiest way to keep your system clean is to keep it moving. It’s not just your tank that is susceptible, but your irrigation lines, your manifolds, your garden beds – even net pots can get slimy and gross. Stagnation is a precursor to mildew and algae, and a good strong pump can do wonders for keeping a system in top shape.

Monitoring the water level, pH and electrical conductivity (EC) in the reservoir is essential to determining when to change the nutrient solution for your exact setup. Measuring the EC lets you know the concentration of mineral nutrients in your solution by checking their conductive strength. The more minerals, the more conductive the solution. 

It is standard industry practice to drain and flush your nutrient solution at an interval that coincides with your total replacement of solution. 

Let’s imagine a hypothetical nutrient reservoir of, say, 20 gallons. Your plants will consume some of the hydroponic solution and a small amount may evaporate, so we will say you lose 3.5 to 4 gallons every week.

If you mix up and add nutrient solution each week to replace what is used, after 5-6 weeks you will essentially have replaced your entire 20 gallons of original solution.

Still with me?

So at this point, most experienced hydroponic gardeners will drain the system and sterilize it with algicides, moldicides and virucides before flushing thoroughly with clean water. Dispose of the old solution in your favorite flower bed or outdoor garden and fill your system back up with clean water (do not recycle solutions that show signs of contamination). Get the pH tested and set, then check the EC so you have an idea of which nutrients you need. Mix up the new solution and you’re back in business, with zero-worry about all the nasty business that can go on in the dark corners of your hydroponic garden.

To reiterate, using our 20 gallon example tank above, you would drain and replace the nutrient mix every 5-6 weeks.

Best Hydroponic System Disinfectant

Physan 20 Broad Range Disinfectant, 8-Ounce

Do I Need a Backup Reservoir?

Unless you have a very large (or inefficient) hydroponic system, you shouldn’t actually need a backup tank. There’s nothing wrong with installing one, of course, if you don’t mind the extra piping and maintenance. We advise that if you do install a backup reservoir, you use a timer to circulate it with the main solution every 6-12 hours (how long depends on the flow of your pump and the volume of your tanks). 

This helps ensure that neither tank stagnates, and keeps the mineral concentration balanced between the two. You will want to test pH and EC vigorously until things stabilize and you get into a state of familiarity (not complacency). Typically, you would install a float switch in your main tank, triggering a solution transfer from the backup in the event it gets too low. 

Backup reservoirs may add to the maintenance time and to the materials bill, but they can be worth it in terms of peace-of-mind. Knowing that an entire crop won’t be stunted because you lost track of how much nutrient solution was in that black tote under the garden bed can be worth a lot, actually.

One thing that gets people mixed up when dealing with backups is the understanding of what is included and what remains to be purchased. When you plan a backup for your system, count on needing an extra water and air pump, at least 50’ of tubing depending on your setup, another airstone, and any fittings that aren’t included with your chosen backup container.

Best Hydroponic Nutrient Backup Tanks 

BLUMAT Water Reservoir || 5-Gallon Bucket w/Lid & Bulkhead Fittings Installed || Ready for 8mm Super-Flex Tubing, Blumat Watering Sensors & Irrigation Systems || HDPE Food-Grade Plastic

The Blumat Nutrient Reservoir is a convenient choice for the gardener itching to get started ASAP! It holds 5 gallons of pre-mixed nutrients and comes pre-fitted with bulkhead fittings ready for tubing. This is perfectly sized for a small indoor hydroponic garden, or can easily be fitted with floats and sensors to work as a backup or part of a staged nutrient delivery plan.

General Hydroponics 706215 Controller, Brown/A

Don’t be deceived by its name, the Controller by General Hydroponics makes for an amazing backup nutrient delivery system. It features a design that can accommodate up to 8 farm modules and your order includes a 13 gallon reservoir, an 8 gallon controller, a length of tubing, some fittings and a float valve. Additionally, at 23.7” x 16.3” x 14.6”, it can easily fit in a corner or under a table and out of the way. 

DIY Hydroponic Nutrient Tank How-To

We know what it’s like to work with a budget, and that high-tech gardening can quickly start to look like high-cost gardening. 

We know – and that we are doing everything we can to make sure everyone has a chance to become a hydroponic gardener.

We are going to walk you through the process of preparing a nutrient tank for use in your hydroponic garden. Because the nutrient tank setup can vary significantly between the different hydroponic gardening methods, we are going to assume the following:

1. The nutrient tank is located underneath the garden beds.
2. The hydroponic garden setup includes both an air and water pump.
3. We have no need to install a backup reservoir.
4. The tank is feeding a Nutrient Film Technique (NFT) hydroponic setup. Imagine the plants in a straight line, with their net pots hanging inside something like a plastic handrail (or 6” PVC pipe). I’m going to refer to ours as being mounted vertically, in an “S” shape on an indoor wall.

(Nutrient Film Technique)

The plants sit in holes cut along the tops of these rails in net pots, with their roots hanging down inside. As the nutrient enriched water floods the top rail, gravity brings it down to the next. Once the solution reaches the bottom rail, it is gravity-drained back into the tank.

Now, we’re going to use a 20-gallon tote with a lid in our tutorial, but the instructions will be general enough that you should be able to apply them to your own setup. 

Rubbermaid Commercial Products Brute Tote Storage Container With Lid, 20-Gallon, Gray (Fg9S3100Gray)

• First, thoroughly clean and dry both the tote and lid according to the details provided above. 
• Now you can layout where you need your holes for the bulkhead fittings. A tape measure and sharpie will work just fine. The most important thing to remember is keep the return up high. Both lines can go through the lid or the side, but if you send both sides through the lid be sure to mark “Supply” and “Return” somehow. You can order different colored barbs, hang tags, use a label maker, or simply write the respective letter with a sharpie. 
• Your water pump is likely submersible and needs to be in the bottom of the tote. In our tank, we mount an isolation valve on the lid with a 3/16” barb pointing up and down on either side of the valve. This way we can close the valve and disconnect the pump for maintenance without having to drain our supply line, which has been isolated.
• In our setup, we will simply use a ¾” or ⅝” garden hose to drain from the bottom channel down to the nutrient tank. If it’s a straight shot, we could use one piece of pipe straight down. If you want to tuck the tank out of the way, you may need to run rigid drain piping out of ¾” PVC. For a professional, leak-free connection, use barbed fittings on the supply side that are rated for your pump. The return side can be a garden hose through a hole, or PVC bulkhead fittings
• That’s pretty much it! Connect the supply side tubing of your hydroponic garden to the vertical barb you designated “Supply.” On the “Return” side, make sure your ¾” PVC bulkhead fittings are snug at the bottom of the rail as well as at the top of the tank. Generally, the more fittings you have, more opportunity for leaks. However keep in mind you will be emptying and removing this tank every 5-6 weeks for cleaning and disinfecting. Unions and valves can save you time and trouble down the road.

After you’ve filled your lines and rails/beds, be sure to have more solution ready to refill the nutrient tank if it gets too low. Watch for leaks over the first 48 hours, especially where you have fittings.

We hope you enjoy your new tank! Once you see how easy and cost effective it can be to Do-It-Yourself, you’re going to want to have a hydroponic garden growing something in every room!