This is how I ensure correct feeding of seedlings in a simple tote-based DWC. It's nothing new, DWC growers have been doing this for years. I'm not going to trademark it as "Bubble-Dro" or start a club. I just get a lot of questions about it and am tired of typing the same answer over and over.
First, I have nothing against drips. A well-designed and calibrated drip system can water very reliably. I just don't like submerged pumps and feeder tubes and think it best to eliminate them when they provide no advantage. For a small growing area built around a bucket or a tote, this is easier, less costly and works better. I'm not describing the entire system here. I'm assuming a tote with holes cut for netpots and the use of hydroton and rockwool cubes or Rapid Rooters (which I prefer).
This approach is the "real" bubble-based hydroponics because it relies on and is powered by the bubbles, not a pump and tubes. So the heart is a good pump. I use a 600 gph Sunleaves that runs 30-40 dollars. You can get by with less but the aquarium pumps are usually not adequate. Next comes the airstones. I use two different totes, a 10 gal and a 15 gal. For the 10 gal, I use 3 airstones and for the 15 gal I use 4. I get 12 inch stones, the kind that are all stone not a piece of stone inlaid in plastic. Check them in your kitchen sink to make sure they bubble well. Scrubbing them with a brush if needed. These get clogged so check them often once you get started to make sure you have the needed bubble action. I use new ones for each grow. You can get a manifold with multiple outlets and shutoff valves for your pump. Those are good but if you have a 4 way splitter with no shutoff and only running 3 stones, run a tube from the 4th and leave it outside and clamp it off well.
How do you know if you have enough bubbles? Hold your hand about 2 inches above the water. You should feel tiny bubbles breaking on your hand. If not you need more air pressure. So now you have your bubbles and you're ready to put them to work. You want to be able to control exactly how wet your pots are getting and to be able to dial it up and down. You can do that with water level. I start by setting water level 2 inches below the bottoms of the netpots. I then load a netpot with hydroton and a rockwool cube or rapid rooter, but no seed. I use this to monitor wetness because I can easily pull it out, open it up and check the wetness. It should be damp but not sopping wet. You have to develop a feel for how damp/wet with experience but too wet can cause stem rot. Too wet, lower the water, not wet enough, raise the water (in small increments). I recommend you leave this monitoring netpot in the system for the first couple weeks of your first grow, but after that you will have the idea and won't need it.
When roots start emerging they are being watered/fed by the breaking bubbles in a fine mist not unlike an aeroponic spray. The airspace between the water and the lid, the space where the root system grows, is a 100% humidity environment that is about as good as you can get. I start light nutes on day 7. Once the roots are well into the water the bubbles are no longer critical for feeding but are still maintained for oxygenation of the water.
Compare this to a submerged pump driving water through tubes that clog and don't allow reliable control over how wet the cube is. In my opinion, the only thing worse than a Frankenstein-ish mess of tubes on top is the same mess hidden in the reservoir. It costs more, it creates heat, it breaks down, it clogs. You may see so-called comparisons set up to prove that pumps and tubes lead to faster growth. There is no logical reason why they would and such results are easily obtained simply by, intentionally or unintentionally, doing the DWC side of the comparison wrong.
You can start a seed this way, I germinate mine until they crack first just to make sure they are viable seeds. No approach is right for every grower. But if you want a small grow system that is as easy as it gets to make and set up, and that veteran DWC growers have gotten great production from, try this! It costs next to nothing, the only real additional expense over what many of you are using now or contemplating, is a robust pump which you really should have anyway.
