This bud is just about ready for harvest. I removed large yellow leaves for the photo. Slight discoloration of leaf tips and leaf margins suggest slight nutrient imbalance.

Healthy well formed compact Citral bud.

The EC of their water is 0.7 and the pH is 7.8. It is packed with salts, of which calcium is the worst. They use reverse osmosis water as a base to avoid nutrient lockup problems.

Water comes out the tap at 10 degrees C. (50 degrees F.). According to John, if you give plants this water, it is “like dumping cold water on your balls!” They shrivel up. Heating the water to 17-20 degrees C (65-70 degrees F) makes it a lot easier for plants to absorb and without shock.

“I don’t worry about EC,” said John. “The EC and pH level always stay relatively stable. Popular Dutch fertilizers Atami and HESI are buffered to remain stable. I use B’cuzz A and B as a base, then I use the Atami root stimulator (www.atami.com) to prevent degradation of the soil and roots. We can use soil 4-5 times, after that it looses texture and air holding ability. Then I use the Atami flowering mix with an enriched level of phosphorus (P) and potassium (K). The fourth week of flowering we start using PK 13-24 from Canna (www.canna.com), or you can start to use it as soon as buds look good like they are starting to really crank flowering. When the basic form of the top is there, PK 13-14 makes it fill out well. I water them clear water twice the last week.”

John sets the pH at 5.3 at first. It will rise when it comes into contact with the growing medium and stops at 5.7-5.8. In general, John has found that when the pH gets above 6.0 leaves start to yellow, which means a lack of some nutrients. If the pH dips below 5.0 stems start to turn purple signifying other nutrient lockups, and if there are little spots on leaves, there is probably too much food.

He mixes as per instructions on the B’cuzz package. If the ground has been used, he does not give any fertilizer the first week because it is already in the soil.

Any salt buildup from plant foods is transformed and removed by enzymes. He uses Cannazym from Canna to keep fertilizer salts from building up. The enzymes take three weeks to start working so they have to be added to the nutrient solution regularly until the final flush at harvest.

You can mix reverse osmosis water with nutrient and store it for the next irrigation cycle. With this single reservoir system, ebb and flow growers are able to fill up their reservoir with the aid of a smaller and less expensive reverse osmosis machine. Large “high tech” systems often require the RO water to be collected for several days or manufactured quickly and stored in a separate reservoir.

Once you mix fertilizer into the reservoir, wait for 10 minutes and measure it again to ensure the pH and EC are stable. Get the reservoir ready the day before to warm and mix completely and make sure it is stable.

All the nutrient solution runs to waste, but there is virtually no waste because plants use most all of the nutrient solution. The trick is to keep the solution running at the proper level. Since it is a run to waste, the solution does not have time to get out of balance. Each irrigation consists of fresh made nutrient solution.

You can use just about any quality hydroponic fertilizer in this system. The real question comes down to how much it costs over the long haul. Fertilizers can cost quite a bit when you are growing thousands of plants. Here is a simple formula to calculate fertilizer cost per liter, quart or gallon. One liter of concentrate makes ____________ (fill in the blank for your fertilizer) liters of nutrient solution. Divide the liters of nutrient solution by the cost to find the cost per liter. Note you can substitute quarts or gallons for liters.

Simple, easy wiring connects ballasts and lights.

The simple design of this grow room keeps down

The Growing Medium

The medium John uses is called PG mix in the Netherlands. The compost base is made from organic plant residues and they mix it with a bit of sandy potting soil and 10 percent perlite. It is very light and fluffy and it wicks up water well. The trick is to fill each pot carefully so that it does not compact and loose its air holding ability. Do not pack the soil or it will compact and drive out air. Mediums such as gravel, sand, expanded clay, etc. are unable to wick in solution and are unsuitable for flood and drain systems.

“I use just about any growing medium and have good results. I like this PG soil mix I get at the wholesale nursery in town. I also like rockwool and coco coir because these mediums hold plenty of water and air within their structure,” said John and continued, “but you have to keep the pH under control.”

Page 1 | 2 | 3