Its been about three days now and the new babies seem to be doing well. I check daily, but no roots - yet There is some slight fading in the leaves, but its not bad and they are not drooping, so I dont think I will change anything - LITFA!
Here is some of the thinking that went into this build.
One of the main reasons for my first hydro experiment was to test the Membrane Meniscus system. If you are curious about the details of that system, its all in the first few posts of the grow thread I linked above. Basically, its whole 'thing' is to provide the absolute thinnest possible layer of water/nutes to the roots at all times. The theory being that a super thin layer of water will self aerate and stay at 100% DO all on its own. That this layer is able to get O2 from the air and transfer it to the roots most efficiently. There are some other benefits to that technique, but thats the main one.
This fit nicely into what I had been reading about hi-pressure aeroponics and fogponics. NASA did some research a few years back and discovered that water droplets in the 20-50 micron size were the ideal size for passing nutes and O2 to roots. 50 microns makes for a pretty thin layer of water :smiley
In my experiment, the Membrane plant did start out doing better than the NFT or E/F plants and had more and larger buds when it went into flower. In the end the plants were all more or less the same, but I think the membrane plant would have done best if the roots had not gotten through my 'membrane' and down into the nute solution.
In any case, I am convinced that less water and more O2 is important. The question is how to get there equipment wise? I cant afford a hi-pressure aero or fog setup and the Membrane technique is just too fussy to set up. Plus its kind of boring - no gizmos!
So that left NFT or low pressure aero. The vast majority of NFT setups Ive seen are not really NFT. They use hi volumes of water flow which results in more of a Nutrient FLOOD Technique rather than a Nutrient FILM Technique. Flooding is not the same as a film. A true NFT setup just has the thinnest layer of water on the roots at all times - which almost no one actually does. Note that thin film thing - as in the Membrane technique and as in hi-pressure aero.
I couldnt come up with a good way to do a true NFT setup with what I had to work with, so I decided to compromise based on what I can afford and have on hand - with the main design goals as follows:
1) I need to be able to start clones or seeds and grow them to harvest in the same system with only minimal mods when switching from seeds to clones.
2) I want to provide the minimum amount aerated water with the max O2 to the roots at all times - no dry roots, but no flooded roots either.
So I ended up going with a DIY sprayer system thats going to be ON for the minimum amount of time and off the max time possible without drying the roots. With my Sonoff timers, the shortest time ON is one minute, so thats what Im doing. Im at 45 minutes OFF now and my bump that up to one hour later to see how that works out.
This is a long way from the ideal constant, uniform "thin layer" of water, but its the best I can come up with on a budget. The roots will be flooded for one minute, but most of that water will drain off very quickly, leaving the roots with just a thin layer of water/nutes for the majority of the time.
Im actually quite confident it will work just fine. From what I have read so far, I don think it really matters all that much which technique you use as long as you keep the main critical factors in line - proper temps, PH and nute concentrations. They can all be successful.
Other than that, Im running the lights at around 100 watts at night, but I have to turn them down to around 30 during the hot part of the day. They are running 24/7. Im not going to be able to continue this grow to harvest unless the outside temps drop a LOT, so most likely I will root these babies and maybe swap out the older clones for future mothers. I suspect it will be mid to late Sept before I can do a full grow again.
Ive bumped the EC up to .5 (250 PPM). I have seen good reports from people running straight water for clones up to full nutes with an EC of 1.3 or 650 PPM. It makes sense to me that the plants need some nutes to help them grow new roots. Im keeping the PH in the 5.7 - 5.8 range.