I thought I had my head wrapped around this until, of course, I got to the point of flooding and draining my newly built system. I'm not sure at all how long the pump is supposed to pump the nute mix from my res onto my table and I'm not sure how long the water is supposed to take to drain from my table... I did a test run tonight (again) without any pots on the table. The table is 5x5'. I ran the pump (265GPH) for 10 minutes and that covered my 5x5' area with 1.5 inches of water. The nute mix semed to take forever to drain back to the res. Actually it never completely did fully drain back. Would it be in my best interest to add another drain on the table? With 1.5 inches of mix on the table I did the math and it works out to 23 gallons of nute mix on the table. My resevoir holds 37 gallons. I would be using 8" wide by 5.5" tall pots and mini Rockwool cubes (the TINY ones) as my grow medium. Around 45 total pots on the table. Can anyone with some experience give me any sort of starting point to work with? I'm so lost and confused right now...
Flood and Drain Questions.
- Thread starter Paola
- Start date
laserbrn
Well-Known Member
Well, I don't know about using pots on the table. I guess I am just a little confused. You are going to use a flood tray, why not just use 6" rockwool cubes and put them on the tray?
Sounds like what you need to do is set your overflow @ 1.5 inches. That's a reasonable depth. Rockwool will pull the water up with it's wonderful capillary action.
I generally drill a few small drain holes. I flood it and watch the fill rate. If it fills pretty consistently fast I'll drill a couple more drain holes. I basically want it to fill about 50% faster than it drains. Once I achieve that correct rate, set the overflow, and set the timer. With a larger table like you have you will need longer flood periods that's all. Just to give the trays a chance to fill. If it takes 10 minutes to get to the 1 1/2 inches then set your timer to run for say 15 minutes. 10 to fill - 5 minutes of fully filled drinkage and it should take about 15 minutes to drain. ~ 50% slower.
Sounds like you are on the right track. They key to remember is it's easier to make it drain faster, it's harder to make it drain slower.
Sounds like what you need to do is set your overflow @ 1.5 inches. That's a reasonable depth. Rockwool will pull the water up with it's wonderful capillary action.
I generally drill a few small drain holes. I flood it and watch the fill rate. If it fills pretty consistently fast I'll drill a couple more drain holes. I basically want it to fill about 50% faster than it drains. Once I achieve that correct rate, set the overflow, and set the timer. With a larger table like you have you will need longer flood periods that's all. Just to give the trays a chance to fill. If it takes 10 minutes to get to the 1 1/2 inches then set your timer to run for say 15 minutes. 10 to fill - 5 minutes of fully filled drinkage and it should take about 15 minutes to drain. ~ 50% slower.
Sounds like you are on the right track. They key to remember is it's easier to make it drain faster, it's harder to make it drain slower.
If the table were to fill for a total of 15 minutes until pump cut off and then drain 50% slower the drain time would be 30 minutes. So 45 minutes of total time of the Rockwool receiving water to soak up. Is my math correct? I have no idea if that would be too long or too short of a time. Also, with all that Rockwool in each pot how much of my 37 gallon res can I expect to lose off of one flood cycle? It seems like it would be significant.
laserbrn
Well-Known Member
Your math is good. I am assuming that for you to get the full 1 1/2 in. in the tray it takes about 10 minutes. That means it will only be at full capacity for about 5 minutes before it begins the slower drain. Your rockwool cubes will suck up a significant amount of water, but with a big resevoir like you have I don't think it will be too bad. I generally find that the plants drink about 5 gallons every two days when they are fully mature and drinking the max amount. That's with 8 fully mature 4 week veg plants. So probably 2-3 footers.
I'am with what you say there laserbrn,The rockwool will hold alot of water for some time.You will have to see how long it takes for the rockwool to dry out and set the timer to flood when dry.From what I can guess is in the pots you have some hydroton with the rockwool {tiny ones}.The water you said dosent all drain back to the res,The roots will grow to the water and thrive.The first flood and drain will tell you how much water you need to top off with.this is how you can judge there up take of water and the mix you feed them.You are on the right track check out some of the growFAQ here they will help you too! PEACE
potroast
Uses the Rollitup profile
What you need to do is fill all of your pots with rocks, and put them into the bed, and fill it. With all of the space taken up, your 25 gallons will fill to a higher level in the same amount of time.
If you use rockwool cubes alone, you won't really have an ebb&flow in the true sense, as the rockwool is better suited to drip. So go with an airy medium like growrocks so you can flood it.
You should have a larger res to flood that big a table, and a bigger pump, too, but I guess you're finding that on your own.
HTH
If you use rockwool cubes alone, you won't really have an ebb&flow in the true sense, as the rockwool is better suited to drip. So go with an airy medium like growrocks so you can flood it.
You should have a larger res to flood that big a table, and a bigger pump, too, but I guess you're finding that on your own.
HTH
Funny that you say all that because I just came to all those conclusions tonight. As soon as the pots get on the table I'll run another test and post results.What you need to do is fill all of your pots with rocks, and put them into the bed, and fill it. With all of the space taken up, your 25 gallons will fill to a higher level in the same amount of time.
If you use rockwool cubes alone, you won't really have an ebb&flow in the true sense, as the rockwool is better suited to drip. So go with an airy medium like growrocks so you can flood it.
You should have a larger res to flood that big a table, and a bigger pump, too, but I guess you're finding that on your own.
HTH
laserbrn
Well-Known Member
How is rockwool "better suited" to drip? Maybe we just haven't gotten it dialed in right yet, but my buddy's drip system when we used Rockwool had a hard time with overwatering. The rockwool retains a ton of moisture and stays wet. Now we set the drip up with Hydroton and I have my Ebb & Flow with Rockwool cubes. Everything seems to work really well for both of us now.
potroast
Uses the Rollitup profile
With dense media like rockwool, you can drip into it and the solution spreads outward in all directions very quickly. With looser media like rocks, the drip doesn't spread much at all.
The trick with rockwool is that it cannot sit in any pooled solution. If it's suspended over drainage channels, you can keep it wet, and it still has plenty of air. So if you flood rockwool cubes or slabs, the ebb must be absolute. (heehee)
HTH
The trick with rockwool is that it cannot sit in any pooled solution. If it's suspended over drainage channels, you can keep it wet, and it still has plenty of air. So if you flood rockwool cubes or slabs, the ebb must be absolute. (heehee)
HTH
tricka
Active Member
here mate this should be in all ebb and flow growers handybook---- http://www.angelfire.com/cantina/fourtwenty/articles/eftips.htm
tricka
Active Member
yeah i know Beag's but im just a brother throwing out some help, you dont always have to follow that calculation but its a good base, its sounds as if Paola has been indoor growing for a while but in relation to some of his questions i really thort he should know some of the main variables that will effect his overall outcome on yield and plant/bud quality, thus resulting in the desired flooding time to his personal set up.
im using rockwool and i need a little guidance,please help..........i have 3x6 table with about 15 plants per table in 6x6 inch rockwool cubes,im currently flooding 2x per day for 15minutes.The water comes up the blocks about 3 inches;ive been doing ths in the veg and flower stage..........it works but hasent been looking the greatest........i would really appreciate some guidance.............
toostonedto
Active Member
Isn't it key to put a layer of hydroton up to like a 1/2" below the maximum flood height, then place your starter plug on top and then fill the tray with more hydroton until the plug is covered and the plant is just sticking up?