Homegrown Steps to Ebb & Flow Success

Level table by flooding it with water and adjusting legs until the water surface appears level. This is also the ideal time to check your table for leaks which can be easily repaired with silicone.

Time the flood until the water reaches the desired height and adjust syphon valve to start draining at this depth. The timer should be programmed to stop pumping just after the syphon valve starts to drain. The entire flood and drain cycle should take no longer than half an hour but it is ideal for roots to be submerged for no longer than five minutes.

To avoid the possibility of an overflow, adjust the petcock so the table cannot fill faster than the syphon valve can remove solution.

pH balancing rockwool

Soak rockwool in water with a pH of 4.0 - 5.0 for two hours. Remove and rinse with straight tap water. This will tie up any elements left over after the manufacturing process and eliminate the tendency of rockwool to drift towards the alkaline side of the scale.

pH in rockwool cubes should be 6.2. A pH of about 5.7 in the reservoir should maintain the this level. Check cubes randomly to ensure consistency. If readings become inconsistent during random cube checks, a couple of floods in quick succession are usually enough to bring things back in line. Use a syringe to extract test samples from the rockwool.

To maintain an EC (electrical conductivity - the amount of dissolved salts in the solution) of 2400 in the cube requires the reservoir be run at 1800 mmho/cm. If the EC rises above 2400 EC in the cube during random checks you may run at 800 - 1200 EC in the reservoir.

Never flood with straight water, it may cause your crop to finish growing before they are ready. When the EC in the cube drops down to about 1500, boost the EC in the reservoir back up to 1800. This method used on a four-day cycle will eliminate salt build up and excite the plants into great spurts of growth.

Another method, but perhaps less practical, of applying the feed and drink is to flood the table with an EC of 3000 or more between the third and fourth floods, with a regular reservoir EC at 1200 -1400.

For growers who desire especially high light levels, 60 watts per square foot using 1000 Watt lamps and super vertical reflectors are recommended. Horizontal 1000 Watt lamps tend to have too much radiant heat and can cause the leaf temperature to be too high, even though the air temperature seems adequate. If so you could try directing osculating fans towards the leaf zone. Air-cooled horizontal reflectors allow lamps to be burned horizontally and remove the heat at source, an excellent combination over Ebb & Flow tables.

Two to four flood & drain cycles are recommended per day during daylight hours only.

The Ebb and Flow technique exposes the roots directly to the nutrient solution which results in the loss of the buffer zone associated with growing medium. Erratic pH and EC is caused by the roots acting directly on the nutrient solution. Plants will benefit greatly by keeping these levels steady; therefore, pH and EC meters should be used for exacting control of the nutrient solution.

When using CO2, plastic should be first stretched over the table and cubes fit through cut holes. This will create an ideal super humid root zone environment and will not allow the CO2 to settle into the root zone. The air pumps must now be kept outside the grow room. This ensures that O2 rich air and not CO2 rich air reaches the roots. A separate airline should be fed directly under the plastic so that the effluent root gases can escape.

Root zone heating is desirable to keep roots at about 22 degrees C or 76 degrees F. Be careful not to exceed this as internodal stretching may occur.

Air circulation is a vital factor with plants in such close proximity. It is commonplace to have a separate micro climate within the aerial zone of the plants, causing humidity build up and mould. You will know there is adequate air movement if you can see some gentle leaf movement. This will also help keep the plant stems sturdy to support a greater amount of flowers and fruit.

The flood and drain cycle should take no longer than half an hour.

Hardening Off - When first putting plants onto the table, raise lights up three feet over the plants, within four days lower light to one foot for the remainder of the growing time. At the same time gradually increase nutrient strength from 1200 to 1800 using your EC meter.