How long should I let my pump run?

I have a small test setup that is a DIY ebb & flow system. I've had a couple small plants in it for a few weeks and they seem ok but are growing slow. I'm not sure how long I should be letting the pump run or how many times each day I should be flooding.

Right now it's set up to flood 4 times per day, it turns on every six hours on the hour. So as an example, it turns on at 6 and 12 AM and 6 and 12 PM. It takes four minutes for the tray to fill up to the overflow tube and takes about 12 minutes or so to drain after the pump turns off so if I had the pump turn off right when it's full it would still be about a 16 minute cycle. I currently have the timer set for 10 minutes on so it's about a 25-26 minute cycle for it to flood and drain.

Does any of this sound right, close? Should I change how long the pump runs for or how often it floods?

I'm using Hydroton as a media BTW and the plants are vegging but I want to put them into my flower room asap. This brings up another question, should I flood at different intervals when flowering than when in veg?

I'd really appreciate any help I could get as I'm brand new to hydro and am planning to switch my grow op over to this system.

my times are 8x5mins in veg room and 4x15mins in flower.. plants seem to like it

Never longer than 1/2 an hour.


According to these guys http://www.angelfire.com/cantina/fourtwenty/articles/eftips.htm

A flood that is just enough to fill and empty should do the trick. I run my pump 15 minutes at a time (because of my mechanical timers).

PS: Try their calculator on that link--I think it's pretty good.

Thanks guys for your opinions. I'll check out that link tonight too.

+ repped you both.

I decided to wait until traffic dies down so went ahead and got some figures together and plugged them into that calc. According to the calc I should be flooding about once every hour and they say not to flood during the dark period so 17 floods per day during veg and 11 floods during flower. This is with letting the pump run for 10 minutes each time (it only actually takes 4 to fill) for a total flood drain cycle of around 25 minutes so the tray would only be dry for about 35 minutes at a time when the lights are on. If I put in the 4 minutes number in it says to flood every 45 minutes!!!

Seems excessive but I don't really know so I guess I could try changing to the 10 minute on time schedule and see how the plants react. Since I'm still experimenting with this, I've been running my solution at a low ppm for fear of nute burn. I've heard many different figures as far as what levels people run so I think it's probably dependent on what type of nutes you use.

That is excessive

To use that Calc properly---please read it very slowly and read everything. The first time I used it...I was way off.

You must really take a scientific approach to the calculator. Leave nothing to guess.

For most people they will be within the 300-500 minute range.

(unless you are just using 1 inch media, a very small flood area... or something unusual)

It took me quite a while to get that calculator right...so perhaps try again.

In my flood and drain I run the pump for 4 min every hour the first week / then for 4min every hour and a half/ then 4min on every 2 hours by the time you enter bloom 4min on and 3 hours off continue that all the way threw bloom

so the bigger your plant the less often you feed it

Tee Five said:

That is excessive

To use that Calc properly---please read it very slowly and read everything. The first time I used it...I was way off.

You must really take a scientific approach to the calculator. Leave nothing to guess.

For most people they will be within the 300-500 minute range.

(unless you are just using 1 inch media, a very small flood area... or something unusual)

It took me quite a while to get that calculator right...so perhaps try again.

Click to expand...

The only thing I'm having to guess on is how much water the media retains since I don't have any "dry" Hydroton laying around. It's all in the pots that have plants in them. I know how much is in each pot, how many pots there are, how long it take sto fill and drain and how much water is used in a 24 hour period. All of those figures I'm sure of but I will need to buy another bag of the Hydroton and test it to see how much it's holding. I need to buy more eventually anyway since my test setup will end up being one of four that I'll be using.

I will end up with four trays running different nute level mixes and the plants will get moved from one to the next every two weeks so I can have a small harvest every two weeks. The only exception to this will be when I do a batch of the Green Cush because it finishes in six weeks for some reason. I have SLH, The Church and Sour Grapes for mothers right now and they all seem to finish right around the eight week mark. There's a few Green Cush clones in my humidity dome and a plant in flower too that's in soil. I had a Hindu Skunk mother too but gave it to a buddy since my flowering Hindu Skunk plant is already eight weeks into flower and not done yet. It would throw the whole op off and I already have the Green Cush to worry about, lol. I may abort the Green Cush mission as well to simplify things a bit. Kinda hard to willingly stop growing something that turns out sooooo nice though.

hydroton doesnt hold any water....

seanec327 said:

hydroton doesnt hold any water....

Click to expand...

Acutally, it does...Took some fresh stuff out a bag and weighed it compared to the same amount in a pot thats been in my system just cycling with no plants in it and it weighed considerably less so it does hold water (temporarily anyway). Think about it, hydroton is expanded clay balls which are porous so they will take on water.

well i stand corrected... touche

HAHA!!......no I'm kidding, I'm not really a dick. Thanks for posting though, I like the grow in your sig.

Its always better to slightly underwater plants than it is to overwater them...why not run a few tests yourself? How about you flood it for 15mins at the start of the light cycle and watch till the plants start to show slight signs of underwatering and then flood again...if you record the time between the two floods its what you could set your timer to, then just get it to run at those intervals but only when the light is on...sound any use?

Never. The pump is just for decoration. Just cut the cord off and plant the pump in your soil about six inches deep.

Best of luck!

dinobelly said:

Never. The pump is just for decoration. Just cut the cord off and plant the pump in your soil about six inches deep.

Best of luck!

Click to expand...

I like this one...I think I got it figured out though