Running Solutions in Flood and Drain |
|
 |
| A look at running temperatures, aeration, pump times, irrigation cycles and more for flood & drain systems. Includes information on the range of flood & drain systems currently available from GroWell. |
|
|
Running Solutions in Flood and Drain
There are many Flood and Drain systems on the market these days. It is a tried and tested method and works well in any format with many media. The traditional flood and drain trays are still very popular and give a high level of versatility. Some people use a whole bed of clay pebbles or Canna Coco, some use pots of clay pebbles, coco or cellmax, and some use rockwool slabs. All methods seem very popular and very effective.
New systems like The HydroVator take flood and drain to a new level again with microprocessor control unit and other added features. No matter which system suits the size of your garden, your growing needs or your budget all deliver the full benefits of an active hydroponic system, faster growth and big yields.
One of the main benefits and largely responsible for the large growth rates is the amount of oxygen available to the root zone, not only is there a lot of air content in media like clay pebbles, also whenever the solution drains from the system it drags air down through the root zone. This makes it difficult to effect or slow growth rates by over watering as this only drags more air through the root zone.
Temperatures
The ideal nutrient solution temperature is about 21oC. At this temperature the water is warm enough to stimulate good growth rates but at the same time cool enough to carry maximum oxygen content. The warmer the solution gets the less oxygen it can carry, and under optimum light conditions optimum oxygen content must also be maintained. Try and keep this nutrient temperature constant day and night, winter and summer, to help do this nutrient solution heaters are available, and for monitoring temperatures Eco friendly thermometers and digital nutrient temperature monitors are available.
Nutrient Solution heaters have a temperature setting (set to 21oC), the heater will come on to ensure temperatures don’t drop below this figure. These heaters are submergible and have suckers to attach to the bottom of your tank or reservoir.
To help keep the nutrient solution going above this temperature when the light is on, try and maintain good grow room temperatures with a sensible air exchange system. Don’t let any light hit the solution. You may also want to provide extra protection from the light and heat on your reservoir by using reflective sheeting or blowing an oscillating fan to cool the sides of the reservoir.
Aeration[
High levels of oxygen are needed in the root zone and water to aid with nutrient mineral uptake by the roots and to aid other metabolic functions when in the plant. The more light and heat the more water and oxygen is needed by the plant and the roots, this is why plants will often be a lot healthier and do a lot better in an active hydro system than in pots when under high light conditions where there is so much water and oxygen about. Your system is only as good as the weakest link.
Airstones are often a good idea even in a well oxygenated system like flood and drain. This is especially true during warm conditions to ensure the water has as much oxygen as possible. Airstones in your reservoir also help to keep the solution stimulated and moving as well as helping to buffer the pH a little.
Nutrient Solution Changes
As a general rule you should always change your solution for a fresh batch once every 1 - 2 weeks. In theory the more often you do it the better the final results. With large nutrient reservoirs this rule of thumb works well but with smaller reservoirs new solutions may be required every 3 to 5 days.
When topping up reservoirs between batches of fresh solution, top up with a quarter strength hydroponic nutrient solution. Use this weak top up whatever stage of growth you are at.
This top up solution strength will work well as a rule of thumb on both small plants on weaker feeds and bigger plants on stronger solutions where the plants tend to drink more water. This weaker top up will prevent nutrient solutions from getting too strong between solution changes. (Note: if plants are quite dark green, then use just water when topping up reservoirs)
Pump in and out times
Standard system – pump in and gravity drain out
These standard systems have only one pump to flood the system and when the pump stops the solution drains by gravity back to the reservoir. A standard 15 minute segment mechanical timer can is usually used but you may wish to upgrade to a digital timer if your tray has flooded to the top of the overflow valve in only 5 minutes.
Deluxe Systems – pump in and pump out
The HydroVator Flood and Drain system has one pump to flood the system and one pump to drain the system. The flood times can be as low as 5 minutes and the drain pump helps force air through the roots for maximum oxygenation. The greater flexibility of both pumps and a control unit means you can experiment for better results.
Irrigation intervals
The interval between flood and drain cycles will vary a bit depending on amount of light and size of plant. A good place to start is use the simple guide below which will work well in any situation.
- For young plants in Clay Pebbles, flood every 3 hours. For bigger plants every 2 hours.
- For young plants in Cellmax, flood every 4 hours. For bigger plants every 3 hours.
- For young plants in Coco, flood every 4 hours. For bigger plants every 3 hours.
- Don’t flood and drain your pots in the ‘Lights Off’ cycle.
- The first flood should be an hour or so after the light has come on.
- The last flood should be an hour or so before the light goes off.
- Never let pots dry out.
|
|
|
|
