Need Help Pls.. Flood Table and PPM related

Well after the last harvest i reinvested my profits and bought two 3x3 flood tables, reservoirs, pumps, nutes, ppm meter, etc..

Alright so in a 3x3 table using 6" rockwool cubes... how often should I flood the table? I read some other posts that didnt really answer my Questions...

Based on what ive read, im going to flood it 3x a day for 15mins?? sound about right??

Also I cant find a PPM chart anywhere... I have no idea what my ppm should be during the various stages...

what id like to hear is somethin like this...

"dude.. flood that table 4x a day for 30 mins... during early veg 200ppm work it up to 500ppm and start flowering around 900ppm..." or somethin to that effect....

I only want to veg for about 2-3 weeks and go right into flowering...

.... ive grown for a while now in soil and im really excited to kick off my first flood n drain table... so thanks for your help fellas..

Well, first of all, I wouldn't flood six inch rockwool cubes. But it can be done, and probably once per day is enough. If you want to flood twice, then 1 hour after lights on, and again 3 hours before dark.

Big cubes are better served with a drip, for a short time 2-3 times/day. Flooding is best with a loose medium like growrocks.

HTH

flooding is fine, I would hit a table like that to within an inch of the top of the cubes every 4-5 hours, back it off if they are droopy, rockwool drains quick, make sure the cubes are not EVER in standing water (salts will accumulate and cause problems if left to concentrate in standing water)

for veg, I would go with this for ppm, based on R/O water with 0-10ppm to start

150 ppm 3 days
250 ppm 4 days

350 ppm 3 days
500 ppm 4 days

750 ppm 7 days (mix in a ratio your bloom nute into this 150 ppm bloom, 600 ppm veg)

transition from there to your bloom nute fully. if you dont have RO water, then add these number to your start ppm.

you might need to buy a digital timer for your pumps, as most cheap timers wont give you the control necessary to accurately flood your table to a preset depth for a few minutes.

if you only have a cheap ass timer, then disregard all my advice until you buy one that is worth a shit.

I flood 4" rockwool for 2.5 mins every 3 hours

Thanks you guys rock! thats exactly the info im looking for.. ya know just a cookie cutter basic "to-do" list that I can start with...

I have a hydrofarm non-digital timer with 15 min increments

I can always swap out the 6" cubes for 4"... i just didnt know what to get so i got those hoping that the base on them would be wide enough to be stable...

I can always switch things up... i can do baskets w/ rocks or coco or 4" cubes...

I guess i dont really know the pros and cons with either so any input would be awesome!

Another thought would be to cut 2" off the base of the 6" cubes so they are 6x6x4" high?????

I think ill return them for 4" cubes and follow what works for you...

At the hydro store they had a table going with 4" cubes and 6" cubes with tomatoes goin on in them and no rocks in the tray... im assuming that I dont NEED rocks in my tray with the cubes??

thanks a mil fellas!

oh whats R/O water mean? "regular old" lol???

Wow, I think you can "hear" anything you want to hear on this post? Why would you be watering 6 inch cubes 3 x a day? Whomever is doing that either had not worked a table or has some humongous plants that suck up a lot of water. I have ebb and flow and I water my tables 2-3 times a week for less than 30 minutes. The reson one uses 6inch cubes is to retain the moisture for a period of time, but not saturate the roots. I have a bucket system for my mothers and I run the water over the plants once every hour for about an hour ad then give them a break of an hour. The nutes while in veg that I run is 8000 to start with and before they leave veg (3-weeks) they are up to 10000PPM. I don't know it all and still consider myself a neophtye so i am more than willing to learn, but i want to learn from somebody who has experience. If I could figure out how to post pics on this website I would upload my tables so you could see what my plants look like. Good Luck and happy harvesting.......

Roadhousepsych said:

Wow, I think you can "hear" anything you want to hear on this post? Why would you be watering 6 inch cubes 3 x a day? Whomever is doing that either had not worked a table or has some humongous plants that suck up a lot of water. I have ebb and flow and I water my tables 2-3 times a week for less than 30 minutes. The reson one uses 6inch cubes is to retain the moisture for a period of time, but not saturate the roots. I have a bucket system for my mothers and I run the water over the plants once every hour for about an hour ad then give them a break of an hour. The nutes while in veg that I run is 8000 to start with and before they leave veg (3-weeks) they are up to 10000PPM. I don't know it all and still consider myself a neophtye so i am more than willing to learn, but i want to learn from somebody who has experience. If I could figure out how to post pics on this website I would upload my tables so you could see what my plants look like. Good Luck and happy harvesting.......

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This goes against all my research...I have always heard to flood tables 3x day for 15 mins when using rockwool, as it has excellent drainage capabilities....which is what I have done with apparent succes...and I have NEVER had a ppm anywhere near 8000.....I use AN nutes as directed on the bottle, and my current crop is in week 3 of veg, and my ppm is only around 900. Even AN's nutrient calculator only goes to 1600....are you sure your ppm is that high? I am really confused....because what you are saying goes against every book on hydroponics I have ever read, and if it is working as wll as you say, I may switch some things up.....
Crazy what you can "hear" here.........

I have always heard to flood tables 3x day for 15 mins when using rockwool, as it has excellent drainage capabilities.

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Rockwool does NOT have excellent drainage capabilities. It is highly absorbent due to its fibrous structure and will saturate- and STAY saturated, driving all the air out of the material. Roots need oxygen. Lack of O2 will drown roots and encourage anaerobic pathogens, aka root rot.

ppm, I run flood systems with 175mm dia pots of absorbent media. I used to pack my pots only with rockwool floc. Watering 1x/day was fine for most plants. Plants in wks 1-2 of flowering only needed water every 2 days or so. I've since switched to Fytocell, which holds a lot less water than floc. I can flood mature plants (flowering wks 2- 2x/day, while young plants (wk1-2) in flower can be flooded 1x day instead of every other day.

Roadhousepsych has given you good advice (except for the wacky '8000' figure for nute strength- should be about 1400-1500ppm). 6" cubes will hold an awful lot of water. If you flooded them 3x day, you'd quickly see classic overwatering symptoms like yellowing leaves, slow growth etc. ending in root rot- and the death of the plant.

If you want to flood 3x/day, you'll want to start by cloning in smaller RW cubes (40mm) and nest them in pots of non-absorbent media like clay pellets or lava rock. Your flood level must not touch the bottom of the cube. The flood level should come up to about 1/2" BELOW the bottom of the cube. If you allow a RW cube to be saturated 3x/day, you'll very quickly see overwatering damage. Plants organised this way should have their pellets- not the cube- handwatered for their first week or so in the pellets, until the roots knit down into the pellets below the floodline.

My apologies guys hit the 000 too may times, 800 PPM as beginners to final of 2000. Too stoned last night sorry! Rockwool good, but roots need to "want", not get lazy and just absorb. Healthier plants due to struggle, within reason... Gluck!

Damn thats awesome info fellas... and Al B, thanks for the insight on waterline to 1/2" under the cube!

Well.. with all that.. im already cloning in the small 40mm RW cubes and I dont NEED to use the 6" cubes.. its just what I bought at the time i was at the shop. Im thinking I should go back and buy some Baskets and rocks and nest that cube in there.

Will flooding the table 3x daily be enough turning in the nutes so that they dont get funky on me? Or should i time an airstone to come on periodically through the day to give the brew a stir?

Incognitto said:

Will flooding the table 3x daily be enough turning in the nutes so that they dont get funky on me? Or should i time an airstone to come on periodically through the day to give the brew a stir?

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Run an airstone in the tank 24/7. This isn't for mixing the tank but for root oxygenation.

To keep your tanks funk-free, apply H2O2 (50% grade) at 1ml/litre of tank volume every 3-4 days. Kills pathogens and also oxygenates roots.

im sorry for hyjacking here..al b fuct....i just saw what looked like a thermostat wired for fans and blowers, in the random pics page...it had your name all over it...is there a thread on here that explains how to wire that up.....sorry to disturb......

nickfury510 said:

im sorry for hyjacking here..al b fuct....i just saw what looked like a thermostat wired for fans and blowers, in the random pics page...it had your name all over it...is there a thread on here that explains how to wire that up.....sorry to disturb......

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Yep, you're probably thinking of this one:

https://www.rollitup.org/716806-post1294.html

We can chat about it in that thread, just reply with quote.

Cool cool... so heres the update... i stuck 12 rooted clones in 1" rockwool cubes inside coco baskets which were inside plastic baskets and filled with hydroton...

Using Botanicare's Pure Blend growth i pH'ed my water to around 5.5-6.0... then added approx 30ml pure blend and worked my ppm up to 250... I also added 30ml of H2O2 (ive read 30ml per gallon ... i have 10 gallons in my veg tray and honestly was just afraid of putting more shit in the reservoir so ill probably throw in another 30ml shot every few days (at 10gal 300ml of h2o2 i believe is acceptable)

when i first put my clones in the baskets and in the tray i noticed the water level was too high and coming up to almost the tops of the rockwool cubes... so i cut up some more rw cubes in half and put three halves under each basket to raise them up a bit... now the waterline hits about even with the bottom of the rw cubes my clones are in and seems to be okay

Im flooding 3x daily... they do retain a lot of moisture ... im noticing the tops of the rw cubes are "damp" but not bone dry and not soaked after about 4 hours just before the next flood...

should I allow the rw cubes to fully dry out before flooding and cut back the amount of floods per day? whats the rule here? they are "damp" before the next flood but not soaked...

I noticed my ppm went up to 325 after i added my clones to the tray... however beginning ppm in the reservoir was 250 ... i believe the reason the ppm jumped to 325 was because of some of the dust off the new hydroton rocks... (I did rinse them a bit before putting them in the baskets).

Everything appears alright ...so far... its so cool to come home and not have to ph water bottles and water everything anymore... hydro is pretty tight once u get it setup!!

ill continue to monitor ppm and flush my reservoir in about 2 weeks....

Subscribed for educational reasons.

Thanks.

Incognitto said:

(at 10gal 300ml of h2o2 i believe is acceptable)

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The correct dosage is 378ml in 1 US gallon (3.78L) is 1ml/L. Get used to metric figures, they're so much easier to use.

when i first put my clones in the baskets and in the tray i noticed the water level was too high and coming up to almost the tops of the rockwool cubes... so i cut up some more rw cubes in half and put three halves under each basket to raise them up a bit... now the waterline hits about even with the bottom of the rw cubes my clones are in and seems to be okay

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Space the netpots off the flood tray with a stack of old floor tiles, inverted dinner plates or some other clean, non-absorbent material.

The flood level must NOT touch the cube. It must come to no higher than ~13mm (1/2") BELOW the cube. If you saturate a RW cube 3x/day, you will have overwatering symptoms. Once the roots seek their way down into the pellets, they can be flooded really quite frequently.

should I allow the rw cubes to fully dry out before flooding and cut back the amount of floods per day? whats the rule here? they are "damp" before the next flood but not soaked...

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Now they are in pellets, the cubes are all but redundant. As said, flood only the pellets, not the cube. This will force the roots to seek into the damp pellets.

Al B. Fuct said:

The correct dosage is 378ml in 1 US gallon (3.78L) is 1ml/L. Get used to metric figures, they're so much easier to use.

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Yeah, y'know I just can't get that metric stuff. Ya see, here with our wacky system, 1ml/L is approximately FOUR ml per gallon, or 40ml for 10 gallons, but then, I had to get that with a paper and pencil.

potroast said:

Yeah, y'know I just can't get that metric stuff. Ya see, here with our wacky system, 1ml/L is approximately FOUR ml per gallon, or 40ml for 10 gallons, but then, I had to get that with a paper and pencil.

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You're absolutely right!

See how easy it is to fuck up those silly old imperial figures?

The correct dosage is 3.78ml in 1 US gallon (3.78L), for 1ml/L. Gotta mind those decimal points...