I know this isn’t aquarium related, but it can be if you get into aquaponics (growing food fish and plants in the same system). Plus, a lot of people interested in aquariums are also interested in plants.
It’s a relatively easy transition from aquariums to hydroponics. Hydroponics is growing plants in water instead of soil. There are many variations of hydroponics that use different methods, but they all use water instead of soil to grow plants. Hydroponics removes almost all of the most common issues with soil. The biggest benefits are:
- It’s almost impossible to overwater with hydroponics
- It’s almost impossible to underwater with hydroponics
- Hydroponics avoids most nutrient deficiencies and excesses or at least greatly minimizes them
- Hydroponics helps avoid most pest problems since most are introduced in or require soil at some point in their life cycle
- Hydroponics uses a small fraction of the amount of water needed to grow in soil
- Hydroponics can be much more efficient with space requirements as well
Soil can be mean A LOT of different things and different soils for different uses will have vastly different characteristics. Some drain better, some hold the moisture better, some are more acidic than others, some are more nutritious than others, some include fertilizers mixed in with the other components.
One important difference is that the organic materials in soil need to be broken down by bacteria and fungi before they’re available to the plants. In hydroponics, this is not the case since the nutrients/fertilizers are completely dissolved in the water and the plants’ roots can absorb them immediately. This means that when there are deficiencies and you add things to correct that deficiency, it’s available immediately for the plants to begin using as opposed to the significant delay required when you add soil additives.
Below are two simple methods of hydroponics, Kratky and Deep Water Culture (DWC). These are the two methods I use and are fairly simple. Both require minimal equipment and set up making them easier for a beginner to use.
The simplest method of hydroponics is Kratky. It is growing plants in water with no soil, no water pump, and no air stone. There is no circulation or flow in the water. This method is best with simple, undemanding plants such as lettuces, spinach, greens, and herbs. It can also work with some houseplants such as lucky bamboo, Monstera, etc.
Most people use a simple container which can be anything from a mason jar spray painted to keep the light out to almost any plastic container that will at least keep most light out and that you can figure out a way to hold the plant at the top. I used mason jars with net pots.
For undemanding plants such as lettuces, you mix the nutrients in the water when you first set it up and that’s it. You don’t necessarily need to add any additional water since the plant can get to harvest size by the time the initial quart of water is used. At most, you may need to add some water again, but don’t refill more than half the jar since the roots will become air roots if out of the water long enough and will die if then completely submerged again.
Below is my first batch of hydroponic plants, lettuce and a few herbs, grown in Kratky. The first photo is just after the seedling stage when they were first put in the jars (probably about 7 days old). The second photo is only 16 days later when they were ready to begin harvesting.
Deep Water Culture
Deep water culture, often just called DWC, is one step up from Kratky. It can use the exact same containers as Kratky, but usually uses larger. DWC uses an air stone to create flow which adds a lot of aeration to the water and roots. This significantly increases growth rate. Together with larger containers, this method is better for more demanding plants such as tomatoes and much more. Even with less demanding plants, it can still be a way to greatly increase growth and production.
Below is a young jalapeno pepper plant in a 5-gallon bucket. You can see the air tube going through the lid to the left.
Below is our kitchen tomato plant that grew to the ceiling.
Below is our bin for growing lettuce, greens, and herbs.
There are lots of other methods of hydroponics. The following books are available on Amazon that I found helpful. You can get them many other places as well, always support local businesses when you can.
You can start with tap water, but if you have issues, be aware that they may be caused by stuff in your water. Even after going through a drinking water filter, it will usually leave a lot of things in the water. When in doubt, use either distilled or RO/DI water (the same you would use for a reef aquarium).
There is some chemistry involved. At the bare minimum, you will need a pH meter and a TDS/EC meter that can read electroconductivity (EC). The ideal pH will vary by plant, but aiming for 5.8 is ideal for many if not most and be at least okay for most plants. The pH affects how well specific minerals can be absorbed. You can always google your plants to see what their preferred pH and EC are. You can adjust the pH with pH adjusters such as pH Up and pH Down. These are more effective and longer lasting than other options such as vinegar (which will bring the pH down) and baking soda (which will bring the pH up).
Pure water doesn’t conduct electricity at all. How well water conducts electricity is completely dependent on how many things are dissolved in the water. By measuring the conductivity, we can measure the total amount of solids dissolved in the water. TDS stands for total dissolved solids. EC stands for electroconductivity and is a variation on TDS but you can think of it the same way. If you are using RO/DI water (water that’s been through a reverse osmosis and deionization filtration system) its TDS/EC will be at or near 0. If you are using tap, you need to test the tap and then always take this into account when determining how much to add. We measure the amount of nutrients in the water by testing the EC. The unit of measurement for EC is milliSiemens per centimeter (mS/cm) or microSiemens per linear centimeter (µS/cm). If your plants prefer the EC to be 1,000 but your tap is 400, you don’t add enough to just get to 1,000, you add 1,000 on top of whatever your tap is. In this case, you’d want to add enough nutrients to get it all the way up to 1,400 (400 from the tap + 1,000 of nutrients for the plants to actually use = 1,400).
This is making it sound more complicated than it really is. Adjusting for your tap, simply add enough to nutrients to get to the ideal EC for your plants. If it’s too low, add a little more nutrients. If it’s too high, add more plain water (you might have to take out some if your container is too full). So when in doubt, add less and retest since it’s easier to just add a little more.
For pH, it’s pretty similar. If you’re aiming for 5.8 and you’re starting at 7.0, add some pH Down. Always mix the nutrients first since they can alter the pH. Always add less than you think you need and keep track of how much you add and how much that changes the pH. Again, if it wasn’t enough, you can always add more. What you don’t want is to start at 7.0, add too much pH Down and now it’s at 4.5, then add some pH Up and now you’re all the way up at 7.8, etc. Add less, give it a little time to completely mix, test again, and dose again as needed. Always track how much you add.
Always dip the meters in plain water after use.
Always rinse whatever you measure things out in after each use. You don’t want to cross contaminate different things or have residue of one thing still on the measuring instrument when you use it again (especially when measuring something different).
Test and adjust nutrients before testing and adjusting pH because the nutrients will alter the pH.
Temperature will vary by plant, so keep this in mind if you have any issues. Tomatoes like it a little warmer, lettuces like it a little cooler, etc. Unless you’re getting a grow tent or something and will be able to control and change the temperature and humidity, there’s not much you can do so make sure what you will be growing isn’t completely wrong for where you will be growing them, but you won’t be able to do much more than that in most cases.
Some people do it with even less, but I found the following to either be truly essential or so helpful that I’d never do hydroponics without them.
- Light – Viparspectra LED
- MasterBlend Nutrients
- pH Meter
- TDS/EC Meter
- pH Down
- pH Up
- Containers – your choice, mason jars with net pots are great
- 3″ Net Pots (Fit 1-Quart Wide Mouth Mason Jars)
- 1″ Rockwool Grow Cubes
Not Essential, but Helpful
The following make it even easier to do what you need to make your plants thrive.
- Air Pump
- Air Tubing
- Air Stone
- Better Light – Mars Hydro 3′ x 3′ LED Light
- Better pH Meter
- pH Meter Calibration Powder
- Better TDS/EC Meter
- Phosphorus and Potassium Supplement (to boost flowering and therefore total yield/production for fruiting plants)
- Measuring Spoons
- Measuring Cups
- Graduated Cylinders and Beakers (for more precise measuring)
- Digital Spoon Scale
- Squeeze Bottles (make dosing nutrients and pH Up/Down much easier)
- Medium Fan (for air circulation)
This may sound nerdy and discourage some people, but it really helps a lot to track what you do with your plants. You can see what a specific amount of pH Down did to your 5-gallon bucket of tomatoes the last time you dosed, make notes about when issues popped up, or when you changed things (such as moved to jars, changed how long the lights were on, etc.). Google Sheets is great, free, and available across different devices.