You'all should take a few tokes before reading this
My system is still evolving. It is top feed drip irrigation to waste in rockwool cubes. I water 8 times starting 2 hours after lights on until 2 hours before lights out on the 18/6 schedule so 8 equally spaced watering times over 14 hours . On 12/12 watering starts 3 hours after lights on to 3 hours before lights out same 8 watering periods so 8 equally spaced watering times over 6 hours. 1 minute is the minimum run time which is 3.4 ounces for each cube. Period 1 = 1 minute, 2 = 1 minute, 3 = 2, 4= 2, 5 = 3, 6 = 3, 7 = 4, 8 = 4 minute run. Or about 60 oz per day per cube. I increase this when I notice I am not getting enough runoff. Whew...... The idea here is to prevent channeling in the cubes and to get a 20% of the water applied to exit to waste. I have a 10 gallon reservoir attached to a 35 gallon top off tank. The top off tank holds aerated PH 6.0 water. The nutrients in the reservoir start at the PPMs appropriate for the stage of growth; say 1000 PPM I allow it to drop to 700 PPMs then add nutes to bring it back up. Since I drain to waste the balance intended by the vendor is maintained. I do drain and clean the reservoir when I Flip to 12/12.
I know it seems complicated and it was at first but I really don't have to think about it much now. Here is a long winded version of the precision watering schedule:
Ok so after communicating with the west coast GroDan rep; there is a newer “Precision Watering” method recommended in
my scenario that supersedes the previously published information. I am going to reiterate the information sent and discussed with me here and I will try to explain what it means to me in my 6 plant grow as well as some of the ideas behind the changes. You want to slowly water about 3% of the capacity of the rock wool block on each pump on cycle with enough cycles to accomplish a 10% to 20% of that total volume as run off by the end of the watering period that day.
Watering Formula
1 Gallon of Water = 231 in3
1 Hugo = 216 in3 (.94gal)
1 Ounce = 1.805 in3
1 Gallon = 128 oz.
Formula:
216 ÷ 231 = .94gal. x 128oz. = 120 x 3% = 3.6oz.
Whew….. Ok so let’s talk first about that small 3.6 oz. of water (nutrient mix) per cycle for the Hugo. I could not understand why such a small amount of water per cycle until in the course of our conversation the topic of “Water Channeling” came up. When you water in larger faster volumes the water develops “channels” through the block instead of permeating the entire block. Smaller slower more frequent watering provides a more desirable capillary action. This capillary action moistens and aerates the block more evenly which is the goal as opposed to just the areas close to the channels. It was like a light went on for me with this revelation. Using “X” number of water cycles per day to achieve a 10% to 20% run off of the total water applied in those cycles by the end of the day has to be accomplished by observation and measuring the run off. This small runoff is what is flushing any salt build up out of the block daily. The number of cycles in a period is going to change as the plants uptake changes and I think I have figured out a way to keep tabs on that in my system. More on that as the grow proceeds.
The “when” to water patterns has changed as well from previously prescribed regimes, it is now recommended for me in Veg. to start watering 2 – 4 hours after lights on until 4 – 2 hours prior to lights out. So this is a 12 to 14 hour watering window in veg. Listening to your plants is part of determining when to start and stop within these hourly ranges. Remember you need to achieve that 10% - 20% runoff of the total by the end of the watering time frame. Not watering during lights out is going to provide a very important “Dry Back Period” in the block which stimulates root growth and health.
In flower mode you water from ~4 hours after lights on until ~4 hours prior to lights out. Here we are talking about a 4 hour watering window in which to accomplish the runoff. Shrinking down the watering window places more stress on the plants to strive for “survival of the species with bigger better flowers hoping to get pollinated” at least that is the theory behind it. I think that this may set a very fine line between good stress and too much stress that can cause hermies in some strains. Consequently I may opt to be a bit conservative here.
When I am ready to transplant the A-Ok starter blocks into the Hugos, I will prepare the Hugos by following Grodan’s instructions soaking them in 5.5 PH water for 30 minutes then flushing to waste with ¼ strength nutrients PHed 5.5 to 6.0. Transplant, and then don’t water for 7 – 10 days in order to establish a good root system in the Hugo. Watering should start when the blocks are ~30% - 50% moisture content. Just picking them up is the test here they will be light yet should still have about 36oz to 60oz of water.
The “First drip watering”, It has been explained to me that runoff from this first drip watering will begin at around the 4th cycle which means I will have applied about 14.4oz per block and would be looking for 1.4oz. to 2.8oz runoff; If I don’t get that then I would want to add another cycle in which case I will have applied 17oz and looking for 1.7oz to 3.4oz and so on. Remember I have a big watering window and the plants will not be very large yet so I should be able to dial this in.
Now I don’t want to water again until the block is at that ~30% to 50% moisture content range again which may be a few days or more but now I will have a better idea on the number of cycles needed to get the proper runoff.
As the grow progresses I will just keep ramping up the number of water cycles to meet the plants demands and getting that 10% to 20% runoff as well as keeping within the other watering parameters above.
As you can see I have made some adaptations to this keeping the no-channeling and run-off concepts as key to what I want to do.
