We have been receiving a lot of questions about Pre-Empt. He are some responses to the common questions:
When is Pre-Empt appropriate?
It is best suited for recirculating hydroponic production of leafy greens. It can be used as a direct substitute for conventional fertilizers in NFT, DWC/Floating Raft, and Flood & Drain. When used properly, it won’t clog 1/4″ emitters which is very rare for an organic fertilizer.
When is Pre-Empt not appropriate?
The cost may be prohibitive for drain-to-waste systems. We do not have any experience with the product being used in aeroponic or aquaponic systems.
Can Pre-Empt be used for tomatoes?
-Growth may be overly vegetative and not as reproductive as standard commercial tomato formulas
-Blossom end rot will likely be an issue on larger varieties like beefsteaks
-Works well with grape and cherry tomatoes but still may have overly vegetative growth
-Calcium may be supplemented with an organic solution grade gypsum
What amendments would you suggest to use with Pre-Empt?
-Organic solution grade gypsum and silica may be used to reduce tip burn or blossom end rot
-Inoculants like TerraBella can help reduce biofilms and improve nutrient availability
How do I inoculate a tank with beneficial microbes?
Fill a 5 gallon bucket with water and add 1 oz molasses. Let water sit for 1 day to remove chlorine (unless using RO or distilled water). Add 2 oz. of TerraBella and let sit for 1 day before adding to reservoir. This is enough to inoculated 300 gallons of nutrient solution.
How often should I change the reservoir?
This is going to vary a lot depending on growing environment, system, water source, and fertilizer rate. In general, using a water source with a very low EC and keeping the fertilizer rate low will help extend the life of the reservoir. Some growers flush their system once every 4-5 months and some growers flush every two weeks. The cost to build a reservoir with Pre-Empt may be up to 100x more expensive than conventional fertilizers so it is very important to reduce the frequency of flushes.
What EC should I maintain?
This will depend on source water EC and crop. The target EC is generally going to be lower than the EC used with conventional fertilizers. Generally leafy greens are grown at an EC ranging from .8 up to 1.6. It is best to start low to avoid the development of biofilms in the system
What pH should I maintain? And how?
I’ve seen growers completely ignore pH while using Pre-Empt. The pH may fluctuate from 4.8 up to 7.5 without noticeable effect on the crop. I’ve also seen growers maintain pH levels with citric acid and sodium bicarbonate.
How consistent is Pre-Empt from batch to batch?
There is variability in the product and it is possible that a batch may perform differently than previous batches. This variability is generally minimal enough that growers do not need to adjust practices.