Once you’ve decided upon your system design, cycled and selected your best fish for and have chosen your grow bed, it’s time to consider your options for aquaponics grow media. This isn’t as simple as collecting gravel from your driveway, but it certainly doesn’t have to be an overly complicated procedure. In fact, we’re going to make it very easy on you. There are 5 primary types you should consider based on your needs and budget.
Hydroton is small clay pellets or balls that expand when exposed to water. They are pH neutral and light weight, both of which are essential for most grow beds. The negative side is that this type of medium tends to be quite expensive. Some gardeners amend the expense by using a heavier media base on the lower half of the grow bed and layering the top with hydroton. This may work for your case if price is a factor.
Certain rock tends to be acidic and can change the pH balance of your grow system. An easy way to tell is to just drop a few pieces of your grow media (rocks) into some vinegar. ACV or white distilled will suffice. If it bubbles, it’s acidic. This in turn can harm your plants and fish, ultimately destroying your gardening system. Therefore, a neutral structure is absolutely necessary for a healthy garden.
Expanded shale is mined as opposed to collected via nature – lakes, streams, etc. It’s pH balanced and contains no sharp edges which may be harmful to skin and plant roots. Pros: This type is lightweight and readily available through many landscaping and construction companies. So, if you play your cards right, you could potentially get a really good deal on it. Of course, if you have to have it shipped to you it can be very expensive.
Aquarium gravel is easily found everywhere from your local grocery store or super center, to your favorite pet store or corner hardware store. You may even have some in stock if you have decorative fish in your home or have in the past. Of course, you’ll likely need a lot more than you currently have on hand if you decide to use this option. This type of gravel is usually coated with epoxy, which keeps the pH levels in check. So it’s generally safe for typical aquarium needs. The colorful rocks can also lead to some interesting artistic expression in your gardening system.
Not everyone is going to be interested in sticking to cutesy small plants that work wonderfully with lightweight media. Veterans who regularly plant stalked or heavy plants tend to be fans of drainage gravel. Why? Because it’s heavy enough to keep the substantial sized plants in place and it, get this, drains well. It doesn’t look as nice and pretty as many other types of aquaponics grow media, but it’s relatively cheap and does the job. And to be honest, if the appearance is an issue to you, you can change it later after you’ve sold the majority of your harvest. The pro of choosing this type is that gravel is usually inexpensive. However, it may contain sharp edges that can puncture skin, and it can be heavy. Note: Not all gravel is identical, and some may alter pH levels after a while. So make sure your drainage gravel is pH neutral.
Synthetic Aquaponics Grow Media
This is made from petroleum based plastic and is pH neutral. It can be pricey, but it’s often much more cost effective than stone or gravel due to its lightweight nature. In fact, It’s so light that you may need to layer it with heavier media to ensure it holds your roots in place as the water enters your grow bed. Synthetic tends to float, which may lead to extra cleaning responsibilities on your end. But if you choose this type, you’re alternating pros and cons.
Important Things To Consider
Whichever aquaponics grow medium you choose, they must all follow the same basic guidelines to ensure the best success rate for your garden system. First, they must remain pH balanced in the short and long term time frames. Most small river stones and gravel are usually neutral, but limestone and marble tend to be acidic. Test it if you’re concerned.
Your media must be the correct size for your grow bed. If your rocks or pellets are too large, air pockets will keep your plants from rooting. However, if it’s too small, solid waste may mix with it and clog your root system. Finally, your media must remain intact. If it decomposes, your pH levels will get all wonky, and depending on color of your media, tannin may cloud or discolor your fish tank water. Natural coloring isn’t generally harmful to aquatic life, but it can make it difficult on your end to maintain and tend to the needs of your fish.
Making mistakes is all part of the experience. So give yourself a little leeway and a lot of credit. Go ahead and test you aquaponics grow media and see what works best for your needs and budget. If you find you love an expensive type that you just can’t budget right now, you can always upgrade your grow media at a later date.
One final note; the pH of your water is very important as well. Be sure to go to our aquaponics water testing training lessons page for more info.
Image Credit: waleedalzuhair via Flickr | https://www.flickr.com/photos/waleedalzuhair