Optimum times for Ebb & Flow system?
 

Very new to hydroponics - I made the 11 bottle system and it works well. Tomatoes are growing. I've read that most people use the 15 min on/off timers, but is there an optimum time for soaking the roots and then draining? Maybe flood for 5 minutes and drain for 20? any thoughts are appreciated. Thanks!

The on time needs to be long enough to completely flood the system. 5min on and 20 off would be just fine as long as it completely floods the system. Most timers have a minimum on/off time of 15-30 min except a digital timer. With a digital timer you may be able to set it for as little as 1min on/off times but it may not have enough on/off cycles for the entire day. Example: if you want to set it for 5 min on and 20 off that would be one on/off cycle for every 25 min. Here in Lake Havasu az. we are getting 15 hours of daylight and with one on/off cycle every 25 min that would mean I would need a timer that had a minimum of 36 on/off cycles just for the daylight hours. Because plants don't feed during the dark hours I would probably only water 3-4 times at night. So I would need a digital timer with at least 40 on/off cycles per day.

The digital timer that I have for my strawberry's only has 14 on/off cycles per day. It said on the box that it had over 100 per week and I don't need to set each day of the week but it only gives me a total of 14 settings unless I am doing something wrong. It is Ok though, because it takes 40 min to completely fill the system so I set it for an on time of 1 to 1 1/2 hours depending on the time of the day because of the heat here. That gives me just enough settings per day with one 1 1/2 hour on time in the midel of the night.

GPSFrontier -thanks for the reply. My system fills in about 2 minutes, so I made a digital cycle timer and will try a setting of 2 on / 18 off for three cycles per hour. I liked your point about feeding at night, so I added a light sensor and will have it cycle 2 on / 28 off or twice per hour at night. Is there a maximum dry time that the roots will dry out? Would a cycle every hour at night be too much dry time? trial and error - lots to learn! Thanks

Well I have read that some people don't water during the dark period at all. You might want to keep an eye on them at night for a few days and look for any signs of wilting, if there is then increase the amount of watering. With my peppers I am using grow rocks for a growing medium and I water for 30min on and 2 1/2 hr off. With my strawberry's I am using coco chips as a growing medium and water once a night from 11:30pm to 1:00 am. It gets dark at about 8pm and light at about 5am right now. The coco chops hold moisture about twice as long as the grow rocks do, but the 3in baskets are a lot smaller than the 2 letter bottles the peppers are growing in. I would be interested in knowing how you built your own digital timer and how well it works? Also if you can set it for as many cycles as you need to? They don't have much of a selection at Home Depot or Lowe's and the irrigation timers are very expensive.

Engineer by education, I enjoy working on electronics projects as well. I have made several timers in the past that work very well, so i just expanded on the old one. The settings for on time and off time are 'limitless', with durations of 1 second to weeks?. For a cycle timer, i didnt care about actual times of day, which is why i used the photosensor to determine night time watering cycles. I have also made timers in the past that work on the actual time of day and a duration associated with each on time. i.e. on at 10:05 am for 10 minutes. then off. on at 2:30 pm for 25 mins. then off. etc.

For my other projects, I had the same problems with the generic timers from HD and Lowes:mad:, and the irrigation systems were not flexible enough. So i made them myself. One was with 110V and one was for a boat battery 12V. Some bugs I had to work out here and there, but otherwise worked like a charm.

Joined the forum today and there is a lot of info here! I am a complete novice trying get a system together and I am looking for a timer with something better than a 15 min resolution. GregoryJ, I see you are from Jupiter, is that Jupiter Fl? I am from Naples, just across the state. I look forward to hearing more about your timer and please let us know if you are interested in selling.

kduck63 - welcome to the forum, pretty new myself. Yes Jupiter, FL. If you are ever on the east coast, let me know. I made the timers for my own projects but i am sure i could make one for you. Send me an email "greg at whitecapengineering dot com". We can discuss specifics. Please put "Timer" in the subject line to so it doesnt go to junk. Thanks, Greg

This will be my first attempt at hydroponics. I have done a lot of reading and gathered a few components. If you all don't mind , I'll just sit back and learn as I have zero experience. Most of my advice has come from Hydroponics Gardening - Start a Small Garden Indoors- Helpful Guide.
I'm really excited about getting started.
Thanks

Impressive! The industry specific minute timers I have seen are $$$ for what you are getting. You could potentially have a nice little side business if you could create a competitive and fully digital timer for this type of app. Good idea to integrate a light sensor so you don't have to adjust day/night cycles year round. I'm sure plenty of people would be willing to pay good money for this type of complex functionality.

BrBubba - Thats not a bad idea. Would anyone else on the forum be interested? I know i can certainly beat the $100 Intermatic timers, and provide more flexibility than all of the other digital timers on the markert... If anyone is interested, please send me an email with your requirements and i'll see if it is feasible. Thanks, Greg. greg@whitecapengineering.com

brbubba - I know i could beat some of the $100 intermatic timers, and they would be much more customizable. I'll look into it and see if its feasable. If anyone is interested in knowing more about the timers, shoot me an email (posted above). I'd even consider some custom requests if people want soemthing out of the ordinary. Thanks

Great Info here
 

Hi all. I'm a total newb to both growing as well as hydro, but I'm a bit confused by some of the cycles everyone uses (or seems to).. I have read various places on the web that (a) 5 to 30 min of flood is 'usual' and you should avoid longer than 1 hour floods, and (b) 3 to 8 of these cycles per day (depends on the plant & local growing environment?), with no real need to water at night unless they totally dry out or wilt during this off cycle.

At first glance I thought the suggestions here were more wet than what I had read but after typing that and re-reading the thread I suppose I can see that the more frequent waterers are in somewhat hot and dry locales? Do I have the (a) and (b) guidelines about right though?

This is a GREAT site for info, by the way. And HUGE thanks to Ron for his build your own system plans. After messing with expensive fittings/grommets/containers/flex-hose and leaks/overflowing, the PVC pipe & bottle setup more than does the job, and is perfect for my budget!

Hi in my system I built about 10 myrs ago, I used a fish tank pump of about 18 watts and a normal timer with 15 minute settings. I set this to run between 3 times a day in winter and 5 times a day in summer. I have had some great crops with this set up, growing tomatoes, lettuce, cabbages, roses, chilli peppers, mint and parsley. I am using expanded clay balls for medium in 20 litre plastic oil tanks cleaned with the tops cut off. I often run a single pump cycle at night during summer to prevent drying out. In tauranga new Zealand temps range from light frosts in the morning in winter to about 28C in summer. My set up is on the back deck in the open.