It's a custom DWC setup in 18 gallon tubs. I'll have three total tubs for 15 plants.
We have one tub going with three plants in it. The other will have 6 each.
We're using a digital gauge for pH, PPM, EC, etc.
We're using Voodoo Juice for root growth in the one tub and it says to add it every 3 weeks.
I haven't had to change the pH at all after adding the Voodoo Juice. It's stayed steady between 6.0 and 6.6 the PPM was 730 until I added a bit of 2-2-2 organic liquid fertilizer earlier because of some of the plants yellowing which brought me to 780 PPM. The water temp. stays between 70* F and 74* F --- I don't touch them and all of these numbers have stayed consistent through the first 5 days. The environment is 80-85* right under the lights by about 2 inches.
We have a Fox Farm trio coming for the other two tubs. I'm doing an A/B split test. I've used Fox Farm for a soil grow before.
Room setup:
-3x4 space in a tent
-2x 80 watt CFL veg. lights.
-1x 250 watt HPS I'll introduce once I get the other boxes setup.
-Digital gauge for reading measurements
-250 sq ft humidifier
-4" duct fan blowing cold air form outside directly on the lights.
The setup for each tub:
-1x 18 Gallon dark blue tubs
-2x big air stones in each on good 40 gallon air pumps each for oxygen.
-40 gallon tank submersible aquarium water pumps with
DIG Irrigation AD6 6-Outlet Adjustable Dripper Head, 1/2" Female Pipe Thread on top of them running lines into the side of each black plastic mesh pot poking at the rock-wool cubes.
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What risks do I run changing the water every three weeks? I'll be topping it off with 7.0 pH water every day. I bought a small pump and a 6 gallon jug I can use for draining the water and pumping new water in the tubs.
The Fox Farm feeding schedule
http://foxfarmfertilizer.com/images/pdf/hydroenglish2015.pdf shows to flush your soil every 2 weeks -- so I assume every 2 to 3 weeks shouldn't be bad for my DWC 18 gal setups.
What do you think? Sorry I should have given all this information in the first place.