I am a complete beginner to hydroponics, I built my homemade hydroponic system and started attempting to grow literally this week. I built a very small, six plant model of your most successful model and I am looking for some feedback. It only holds about a gallon and a half of water, and I am currently not using a reservoir. I was wondering if a reservoir is essential or if my plants should be fine? I constructed my model out of 3 two foot pieces of three inch PVC.
I am also wondering if you think this will be too small for growing things such as tomatoes and herbs. I am using both a water pump to circulate the water, and a marine air pump hooked to 2 three inch air stones in my system (to help with oxygen levels). Please let me know what you think about my system and how I can improve it, or if you think it will even work. Thank you for all the great information also, your site is extremely useful!
Answer: Davis- sounds like your homemade hydroponic system is off to an OK start, but I do have a couple of suggestions for you. As a general guideline, I always build my systems to hold 3/4 to 1 gallon of nutrient solution per plant. Ideally, every system would hold one gallon of nutrient solution per plant, but I have found that you can fall just a little bit short of this without too much of a problem.
When you begin putting too many plants in too little nutrient solution, the plants tend to change the pH and nutrient composition of the nutrient solution very quickly. In good circumstances, this means you will have to check and adjust the nutrient strength and pH twice a day (and likely "top off" the system, as the water levels will probably be down). In bad circumstances, the plants use up one nutrient more than another, or the pH shifts too quickly to catch and fix it. In this case, nutrients become unavailable (or even toxic) to your plants and damage can happen very quickly.
When I first started making my most successful hydroponic system, I also tried to make it work with just the nutrient solution in the pipes. Had I used 6 inch PVC pipes, this would have been possible (in my next homemade hydroponic system I will be using 6 inch pipes and NO nutrient reservoir).
So, my first suggestion is to try to increase the amount of nutrient solution available per plant. This will act as a "buffer zone" against changes in pH, changes in nutrient composition, as well as changes in the temperature of the nutrient solution. The most obvious way to do this would be to add a nutrient reservoir to the system. In fact, this might be your only option if the pipes in your homemade hydroponic system are already filled to capacity with nutrient solution.
When designing most of my systems, I usually place the plant holes a minimum of 8-10 inches apart. This gives the user the flexibility to use every single hole if growing smaller plants (like lettuce and herbs), or to grow in every other hole if growing larger crops (like tomatoes and peppers). Even with 20 inches between plants, tomatoes and peppers can get out of hand and grow into each other without careful attention to pruning and training.
The good news is, with only 6 plant sites in your homemade hydroponic system, you should be able to train your plants outward in every direction. This is a practical solution and could work very nicely for you, given the circumstances. Another idea would be to grow your tomatoes in the four corners, and grow herbs in the middle spots. This would allow you to use all of the spots in your system, but would also allow your tomatoes to have just a little more space.
I suspect the tomatoes will eventually overtake the herbs and make it difficult for them to grow during the later stages (flowering). However, this would be OK as most herbs and lettuce varieties produce their edible parts during the vegetative stage of plant growth (and so should be finished by the time your tomatoes are producing their fruits). I hope this helps you out Davis, and Happy Growing!