Plants grown in rockwool slabs need slightly different nutrient regimes than in other systems. PH should be somewhat lower, at 5.8 rather than 6. Conductivity should also be slightly lower than in other applications. It is very important to remember that the readings in the tank may not reflect the reality within the slab. Nutrient should be extracted from the slab regularly for measurement. In a well maintained system there should not be too much variation between tank readings and those obtained from within slabs. If conductivity begins to rise in the slab it will be an indication that irrigation is either too infrequent or too short.
It is necessary to trickle nutrient into slabs for just long enough to get a 10-15% run off. The timer should be adjusted to provide this amount of nutrient at least four times during the daylight period. More frequent irrigation may be beneficial. Remember that as plants grow they will take up much more nutrient and the watering cycle will need to be extended regularly throughout the life of the crop. The regular check of nutrient from within the slab itself is the most important routine for the rockwool grower. If the Conductivity begins to rise then the grower will increase irrigation to ensure run off at each watering cycle. If Conductivity begins to rise then the grower will increase irrigation to ensure run off at each watering cycle. If Conductivity remains high then it is a simple matter to flush the slabs.
It is necessary to trickle nutrient into slabs for just long enough to get a 10-15% run off. The timer should be adjusted to provide this amount of nutrient at least four times during the daylight period. More frequent irrigation may be beneficial. Remember that as plants grow they will take up much more nutrient and the watering cycle will need to be extended regularly throughout the life of the crop. The regular check of nutrient from within the slab itself is the most important routine for the rockwool grower. If the Conductivity begins to rise then the grower will increase irrigation to ensure run off at each watering cycle. If Conductivity begins to rise then the grower will increase irrigation to ensure run off at each watering cycle. If Conductivity remains high then it is a simple matter to flush the slabs.
