# flood and drain



## croniccrag (Feb 15, 2007)

Hi all ,at what intervals should i flood my system for?


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## splifman (Feb 15, 2007)

what medium are you using? It depends how fast the medium drains water. Rockwool holds water like a mofo so if you flood too much you'll kill your babies. I use hydroton and flood three times a day for 15 minutes, during the light cycle.


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## Al B. Fuct (Feb 15, 2007)

splifman is too right about rockwool holding lots of water. I use 8" plastic pots stuffed with loose rockwool (aka 'floc' or 'granulated' rockwool) in a flood system. I only need to flood once a day for 5 minutes. Small plants (under 2 weeks in the flowering area) need less water. Depending on conditions, I may flood them 1x/day for 1 min or 1x/2 days for 2 mins. 

I have the benefit of having 4 flood trays, each with its own tank, pump and timer. Clones go in every 2 weeks and plants ready to harvest come out. This way, each tray contains plants at 0-2 weeks, 2-4 weeks, 4-6 weeks and 6-8 weeks in flowering. The timers can be adjusted for the differing water consumption rates. Plants at 4-6 weeks are thirstiest. This arrangement makes it easier to flush plants with plain water in the last week as well, without altering the diets of all the other plants.


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## TillthedayiDIE420 (Feb 16, 2007)

thanks for the info mates... im going to be growing soil, and ill keep one mother and clone and use hydro


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## croniccrag (Feb 16, 2007)

splifman said:


> what medium are you using? It depends how fast the medium drains water. Rockwool holds water like a mofo so if you flood too much you'll kill your babies. I use hydroton and flood three times a day for 15 minutes, during the light cycle.


I,am using rockwool cubes (4 inch) and flooding it evry 15 mins in the hour?

I'am growing 4 plants.


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## splifman (Feb 16, 2007)

croniccrag said:


> I,am using rockwool cubes (4 inch) and flooding it evry 15 mins in the hour?
> 
> I'am growing 4 plants.


Are you saying that you are flooding four times an hour? Sorry if this is off. If you are flooding more than once a day, it is probably too much. I am not experienced with rockwool. I suggest you follow somehting similar to what Al B. Fuct described, since he grows using a similar medium.


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## croniccrag (Feb 16, 2007)

splifman said:


> Are you saying that you are flooding four times an hour? Sorry if this is off. If you are flooding more than once a day, it is probably too much. I am not experienced with rockwool. I suggest you follow somehting similar to what Al B. Fuct described, since he grows using a similar medium.


 
I,am flooding it 24 times a day,, 1/4 of a hour each time
I forgot to say that they are in veg stage and they are 5 weeks old!


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## jasonxx420 (Feb 16, 2007)

That is to mutch. 3 times a day for 30 min is what i do and i have been doing that ever since i started growing hydro 10 or so years ago. I think that once a day is not enough. Every time you flood your tray you are replacing O2 to the roots.


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## VictorVIcious (Feb 16, 2007)

So .. are you really saying don't ise rockwool blocks in a flood and drain, that would make sense to me?


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## 420penguin (Feb 16, 2007)

Hey vic, who are you asking that question to?

I use rockwool in my flood and drain. I flood 3x a day. Things seem fine to me but I'm not an expert.


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## Al B. Fuct (Feb 17, 2007)

Different shapes and types of rockwool will require different watering. The trick is to keep the medium damp, never saturated or wet. Flooding rockwool several times a day sounds unneccessary to me for any shape other than very small cubes (4") used in NFT or aeroponic systems, which might be expected to support a full sized plant. Something like that would require frequent watering, but not flooding. 

Slabs are usually smaller in volume of rockwool per plant than an 8" pot full of loose rockwool (floc), so my figures from here may not work for you. 

An 8" x 8" pot of floc will soak up about 2 litres of water. That's plenty for a roughly 30" tall plant in mid flower or active veg (ie mothers) for 24 hours, plus about 12-24 hours in reserve. Nice if a pump fails and you don't check daily. 

The trick is to match how much water you give to how much the plant uses. It's a bell curve. There's too little, just right and *too friggen much*. Most newbs overwater plants to death. Yellow leaves? Slow growth? Back off the watering. 

Watering once a day is fine if your medium will store enough water for the plant for that time period. Take a block of rockwool or a pot of floc, weigh it, note the dry weight (in grams). Add water until it drains freely and allow exces to drip away for about 10 mins. Weigh again. Subtract the dry weight and you know how the weight of the water. Since 1g of water = 1ml = 1cc, you know how many ml/cc of water is in your medium. 

Put the wet medium under your lights. Check the weight a day later. 
If the water weight has reduced by 50-66% in 24 hours, it would be OK to water again. 

If the weight remains above ~50-60% of the original wet weight, roots may drown, develop fungus probs, etc. Either give less volume if handwatering or flood for a shorter period with your timer. Dial it down until your pots are fairly light by the end of 24 hours (25% of saturated wet weight).

Ideally, the plant will suck up 50% of the total water in the medium in 24 hours. This should keep root probs at a minimum and give max growth. 

Contrary to newb belief, watering more than a plant needs doesn't force a plant to grow any faster or better. Usually kills 'em. We're not talking turbochargers and fuel injection here. With plants, there's right and there's dead.


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## scottb11285 (Jul 30, 2008)

how many watts do you use over each tray ???? howmany plants do you put on each tray ???? also wondering how much this whole system effects your electric bill every month ????? and just one more question ........ how do you manage odor control ????? is it a problem ????


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## BloodShot420 (Jul 30, 2008)

i start from seeds in an ebb and flow system - i use the smallest piece of rockwool i can to start them off - i put the rockwool into hydroton, as soon as the roots get out of the rockwool the plants can take off - as long as they are stuck in the rockwool - they are growing at a slower rate (as far as i can tell)... if you are trying to get your plant to go in a hydro system, the roots need a lot of oxygen, which is not as readily available inside a big soaking wet brick of rockwool... they dont dry out nearly fast enough.


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## DrGreen007 (Mar 16, 2009)

BloodShot420 said:


> i start from seeds in an ebb and flow system - i use the smallest piece of rockwool i can to start them off - i put the rockwool into hydroton, as soon as the roots get out of the rockwool the plants can take off - as long as they are stuck in the rockwool - they are growing at a slower rate (as far as i can tell)... if you are trying to get your plant to go in a hydro system, the roots need a lot of oxygen, which is not as readily available inside a big soaking wet brick of rockwool... they dont dry out nearly fast enough.


I Found Root Riots to wrk best in flood and drain i flood for 15 min then drain for 30 min


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## hammer6913 (Apr 12, 2010)

scottb11285 said:


> how many watts do you use over each tray ???? howmany plants do you put on each tray ???? also wondering how much this whole system effects your electric bill every month ????? and just one more question ........ how do you manage odor control ????? is it a problem ????


i went to lowes and got a 250 cfm inline 6 inch fan, then a male/male adapter, then a 6 in heat vent that stands verticle (for a wall), for the base I used a 6 inch to a 4 inch reducer , I used an angle grinder to cut slices all aroud the vent, duct tape the bottom, wrap it with screen zip strip it to hold the activated charcoal duct tape it together and plug it in. i vented it out my window. just make sure 1 you have the fan blowing the right direction and 2 you have enough charcoal to cover the air vents you put in the reducerhammer6913


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## Makaaka (Oct 17, 2011)

Actually you cannot over-water a plant. You can starve a plant of oxygen by not having oxygen in the water however that is a problem with 'lack of oxygen' and not over-watering. Look at a deep water culture, the plant is constantly with it's roots under water and there is no problem. I have grown plants with Deep water culture, Flood and Drain (every 15 minutes) and I've even had plants grow in a flood and drain tray but with the roots underwater 24/7. The only thing you have to keep an eye on is to make sure the water is shielded from light so that you do not get algae forming on the roots and if you do not have enough oxygen in your water you will get root rot. You can overcome root rot by making sure that your roots are aerated (water drained) 50% of the time. So I've flooded the trays every 30 minutes for 15 minutes. (15 on followed by 15 off) and I had perfect white roots. Pretty much it comes down to efficiency. Watering all day might not be needed and maybe it is. There are lots of things that can be added to a setup to make it work however there is no such thing as 'over-watering' but there is such thing as 'drowning a plant' due to lack of oxygen.


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