Hello Stan,
If you want to send me a PM with a e-mail address, I'll try and draw up some diagram's to send you. I's really a simple concept. But the hardest part is finding a solenoid to open and close the water line to the misters. I live in a small town, you might have more options where you live on that. But if not I have looked into using a sprinkler valve as the solenoid, and have some ideas on it.
The guy that built the
aeroponic system also built his own cycle timer, but I'm not planning to go to that trouble. I found the
CT-1 Short Cycle Timer that is digital for accuracy down to 10 seconds, and has a battery backup so power loss isn't a problem. For shorter ON times you may need to build your own cycle timer, or spend a lot more money if you can find one. One of the reasons the guy that built the aeroponic system didn't go through much water was due to the real short ON cycle times. I know I said he used a 3 second ON time (remember I said also it was a long tome ago I talked to him) , but I think that was more like what I would have used. I now remember him saying his ON cycle time was 1/2 second. Anyhow I can go over this aspect more as well.
Another reason I think he didn't go through that much
nutrient solution is he also grew his plants in a climate controlled (kind of) greenhouse so his plants had good humidity and 80-85 degree summer days. But If I remember correctly he said he went through around 4 gallons of nutrient solution once or twice a week. I forget what he was growing with it.
As for marking your reservoir, it's just something I tarted doing early on, and find it very helpful. I usually mark them every 5 gallons (5 gal, 10 gal, 15 gal etc.). I would fill the reservoir with 5 gallons of water and use a permanent marker to draw a line at the water line. But it's almost impossible to keep the pen from getting wet, and when it does it wont work again for days. I still use a permanent marker, but I do it differently now. I still fill the reservoir with 5 gallons of water at a time, but now I use a stake knife to scratch a small line at the water line for each level. Then empty it and dry it out. Then use the permanent marker to draw the water level lines and numbers.
To make sure I get 5 gallons exactly, I fill a 1 gallon water/milk jug 5 times. I also did this for one of my five gallon buckets. Filled it with 1 gallon of water, made the mark, and did it again until 5 gallons. So my five gallon bucket is marked in one gallon increments. This way I don't have to fill a one gallon jug 30 times for a 30 gallon reservoir. I just fill my 5 gallon bucket to the 5 gallon water line to be accurate. Doing this also makes it easy to add
nutrients to the reservoir and be accurate at the same time. Even when there is already nutrient solution in he reservoir, and just topping it off with a diluted amount of nutrients. You'll always know how much water your replacing, and how concentrated your nutrient solution because you know the water volume and amount of nutrients in it.
As an example, say I have a 20 gallon reservoir with full strength nutrient solution in it. You don't want to add anymore nutrients because it would be to concentrated. But you don't want to change your nutrient solution every week, and change them at 2 weeks instead. Since your reservoir is marked, you know how much water the plants are drinking daily/weekly. Let's say they are drinking 3 gallons per day, 21 gallons per week.
Now plants only take up nutrients they need and leave the rest, so you know even though they used 100% of the 20 gallon water volume, there are still nutrients in it, just diluted (around 50%) and slightly unbalanced . So I might add 3-5 gallons of full strength nutrient solution back when I top off the reservoir at the end of the week to compensate for the nutrients the plants used during the first week. I know the nutrient concentration at the beginning of week two won't be to strong because I'm only adding back 15-25% more nutrients compared to the 100% water the plants drank up.
Bottom line, instead of just changing the nutrient solution on a specific schedule regardless of how big they are. I go more by clues to tell me when it's time to change it, and normally do nutrient changes anywhere from 1 week to 4 weeks. If I want to let it go for another week, I may or may not add more nutrients back based on how much water the plants are drinking (compared to total reservoir water volume). If I see signs of slight yellowing (dark green leaves turning light green), or abnormal pH swings it's time to change it completely.