1. Using a Clear Hydroponic Water Pump Reservoir 

This is a common mistake with DIY systems and a mistake I made with my first raft system. Most hydroponic systems require some kind of water storage tank, either static and aerated with an air pump or pumped through the system, where it gets naturally oxygenated. 

However, anywhere you find a pool of nutrient-rich water sitting at a pleasant temperature, you risk getting algae to bloom through a process known as eutrophication. A hydroponics users’ worst nightmare! 

We want to keep the high nutrient levels in the water because our plants need those Hydroponic nutrients to grow, so the next best course of action is to ensure your water reservoir is as dark as possible. Having the tank dark stops Algae from being able to photosynthesize, stunting its growth. An added benefit of an opaque tank is that it helps moderate temperature well. 

But be sure to keep the water tank out of direct sunlight. The simple solution is to paint your reservoir with a few coats of black paint. Some people like to use a mixture of black and white color in layers, but the key is to ensure no light gets to your reservoir and the temperature is as consistent as possible.

2. Ignoring pH Levels 

Getting the pH levels in your system spot on ensures that your plants absorb the most nutrients possible, meaning they’ll grow quicker. 

One of the beauties of hydroponic growing is that you can supercharge the growth of your plants by removing weeds, ensuring they have all the correct nutrients, and giving them more sunlight than they would typically get. This can speed up growth by 25% and increase yield by 30%. 

Cast your mind back to high school chemistry for a second; ph is measured on a scale of 0-14, with 0 being very acidic, seven being natural, and 14 very alkaline. pH litmus strips allow you to eye the approximate pH based on a color scale – be aware not all testing strips use the same colors! 

I’ve found that plants typically like a slightly acidic nutrient solution with a pH between 5.5- 6.5. I always use this as a base point before varying the pH as I tinker and test to find the optimal level, but being in this range will set you up for successful growth. The simplest ways to test pH are via litmus paper, which gives you a rough and ready value, or the more precise method (and my favorite) is using a calibrated pH pen. 

3. Not Learning About Hydroponics Nutrients 

If you’re researching hydroponics, you’ve probably realized that nutrients are key to ensuring your plants thrive. Many growers don’t recognize that nutrients were not all created equal and that you must carefully monitor the amount of Hydroponic nutrients in your system. 

Typically, nutrient mixtures will advertise their NPK ratios. These letters all relate to a significant nutrient. N – Nitrogen P – Phosphorus K – Potassium.

Here is my handy list to tell if you need to add more of a particular nutrient: 

– Leaves are dying or have stunted growth – Lack of CO2  

– Leaves are very dark green and still dropping – Lack of phosphates 

– Yellow tips to leaves – Lack of potassium 

– Dark marks on leaves – Lack of magnesium 

– Yellow, wilted leaves – Lack of nitrogen 

– New growth is pale/white yellow – Lack of iron 

4. Hydroponics Oxygen For Drowning Plants 

Plants need to respire (take in oxygen) and photosynthesize. The roots of plants need to breathe. Therefore, we need to ensure the plant roots have a ready supply of oxygen. This is easy to achieve in systems where the water is flowing, such as an NFT build, so ensure the roots aren’t completely submerged. 

However, we need to oxygenate the water in static systems such as raft systems as it isn’t moving around manually. Fortunately, this is easy and reasonably cheap to do by using air stones. Air stones will force air into your reservoir, which will be absorbed into the water/nutrient mix and delivered straight to your plant roots allowing them to ‘breathe.’ Useful reading 1. Is it possible to overwater hydroponic systems? 2. How does hydroponics not drown plants?

5. Getting Lighting Conditions Wrong 

Plants need light for photosynthesis. Hydroponics allows us to deliver sunlight even when the sun isn’t shining. The ideal light system for hydroponics offers a good spectrum of light, stays cool, and uses minimal electricity. 

The standard lighting options for growers are: 

T5 Fluorescent bulbs Pros: • Cheap • Long lasting Cons: • Not suitable for flowering plants High-Intensity Discharge Lights (HIDs) Pros: • Better usable light range than T5s • Dimmable Cons: • Life is much shorter than T5s • Higher risk of burning plants with light intensity Light Emitting Diodes (LEDs) Pros: • Very efficient and long-lasting • More control over which parts of the light spectrum are in the whole light Cons: • Tend to be more expensive Plus some newer types of light which aren’t covered here but are in my complete guide to hydroponic lighting. 

Typically I would recommend T5 Hydroponic lights for beginners on a budget placed around 8” above your plants (adjust as necessary when plants grow). If your budget stretches, go for LEDs at thehydroponicsplanet.com. 

These are far more efficient and will make your life much easier. The placement of these will vary depending on what intensity of the light you have. If the LED has been designed explicitly as a grow light, it will often come with guidance about placement.

6. Using Tap Water 

Many people don’t realize how much effort goes into making their tap water safe to drink. Water treatment is a very intense process; depending on your state/country, the water will have additives unsuitable for supporting your new plants. This doesn’t mean you can’t use tap water at all, but you will need to process it yourself to make it safe for your plants. A common additive to water is chlorine. This kills most harmful bacteria in the water but can be in concentrations far above what your plants need, especially if you add nutrient mixes to your water. 

This can result in stunted plant growth as chlorine can kill off useful bacteria on the plant roots. My recommended alternative for beginners is to buy a cheap water tank to collect rainwater from your downpipes. Rainwater is generally free from most additives, and trace amounts won’t affect your plants. Just watch the pH levels of rainwater as it varies from region to region. I’ve written a detailed guide about tap water which you can read here.

7. Not Checking Water Levels Regularly 

Most growers will shelter their growing systems inside or in grow tents/greenhouses; therefore, the rain can’t top up the water levels as the plants drink. The job of keeping an eye on the water levels, therefore, falls on the grower. As a grower, you need to ensure that your plants receive enough water so that the roots get plenty of access but not so much water that the roots are completely submerged (unless you have an airstone). 

This ensures the roots have adequate access to oxygen and nutrients. Nutraponics systems are often touted as ‘set and forget’ systems for growers, and they often forget to check the water quantities leading to drowning plants. I’ve written about topping off and changing your reservoir water. It will help you avoid shocking your plants with sudden nutrient changes.

8. Not Spotting Root Rot 

Root rot is caused by the plant roots not getting enough oxygen. Root rot can be difficult to identify as it will typically affect all your plants simultaneously. This makes spotting stunted growth tricky. One of the more obvious indicators of root rot is a slight ‘musty’ smell from your plants. If you notice either of these signs, look at your roots; if they’re brown and slimy, you have root rot. I’ve covered how to treat root rot here. Root rot is caused by not having enough oxygen in your water. If your roots are fully submerged, you’ll need to ensure you have an airstone to oxygenate your water.

9. Not Understanding Electrical Conductivity(EC)

 pH levels are generally understood better by growers as it’s taught in schools, but not many people understand electrical conductivity (EC). EC measures the ions in the water; this is just a fancy way of saying extra things that aren’t pure water. The more of these ‘extra things’ in the water, the better it will generally conduct electricity. 

This is important to us as growers as it can indicate how many nutrient parts are in the water. The higher the EC reading, the more nutrients in the water are available for the plants to consume. Checking the EC and topping up the nutrients when it drops too low helps you grow plants bigger, faster, and healthier. I’ve written a complete guide about testing EC, which is helpful if you’ve never dealt with it before.

BONUS GIFT 

I’ve been hard at work putting together what I consider to be the ULTIMATE guide for hydroponics… and it’s finally finished! As a thank you for visiting my website, I want to offer you a copy of the book at a BIG discount. I won’t just give you a copy of the book in eBook form; I will also be throwing in 2 cheatsheets, which I have pinned on the wall. The cheatsheets help me identify nutrient deficiencies and guide me for the ideal pH, and EC range for various crops I grow. I’m not planning to run the discount for long, so check it out when you can!