What up with driving straight Perlite...

[disciple]

Hello.

Doing some work with a drain to waste straight perlite system. Each column of 6 plants share 4 gallons of perlite. After training/pruning the plants each have 4 - 6 shoots at least a foot long. Each plant is within 6" of a 600W HPS.

Trying to nail down some guidelines for when to irrigate. I've been doing it by hand (pump/hose) since they were small cuttings and am transitioning to auto.

from DDoc via Nuggdigger:

__________________________________________________ __________________________________________________ _____________________

Medium: Hydrotron
System: the Cage

When plants are 2 inches to 4 inches tall feed them every 9 to 18 hours when the lights are on (once or twice per day).
When plants are 4 inches to 8 inches tall feed them every 6 to 9 hours when the lights are on (two or three times per day).
When plants are 8 inches or taller feed them every 2 to 6 hours when the lights are on (three to six times per day).
At the stage of maximum water uptake feed them every 2 to 3 hours.

__________________________________________________ __________________________________________________ _____________________

What up with Perlite?

From today's lab work:

1850 ml of Hydroton
- took 800 ml of water to fill to the 1850 ml line
- 125 ml of water retained after pouring it out

1850 ml of Perlite
- took 950 ml of water to fill to the 1850 ml line
- 525 ml of water retained after pouring it out

so we can see that a specific volume of dry Perlite will absorb more water than an equal volume of dry Hydroton (no surprise here). Perlite will absorb about 19% more water than Hydroton

we also can see that Perlite retains more water. Using the above data for a rough approximation, it retains about 420% or 4 times as much water as Hydroton.

So how would using straight Perlite correlate with DDoc's instructions for Hydroton?

For me, week 4-5 will be the time of max water uptake. In other work I scale into (ramp up) and out of (ramp down) this time period in terms of irrigation. I'm watching the plants and trying to get my hands on a moisture meter so the data will be obtained.... I'd just like to see if a good schedule can be determined mathematically.

[nuggdigger]

Quote:

Timing intervals can be longer when using media in the columns because the media will hold a certain amount of solution. We suggest you time how long it takes the pump to produce a trickle of waste nutrient out the bottom of the columns; this is ideally for how long the pump should cycle (be turned on).
The fresh nutrient only passes through the root zone once. It is VERY important to make sure that the roots are getting saturated during every watering. This is why gardeners will want to turn on the pump and time how long it takes for the first bit of waste water to trickle out of the bottom of the columns. Always increase timing intervals gradually to ensure ON cycle is long enough to prevent the plants from drying out. The reservoir will need to be monitored to avoid both overfilling it on one and or running the pump dry on the other.

From The Cage manual.

[disciple]

Quote:

Originally Posted by nuggdigger

From The Cage manual.

I can get some runoff with a 1585 GPH Mondi on for a minute, 7 seconds.....

I'm more trying to understand how many times a day (week?) the pump should come on. Don't understand what the wet/dry cycle is like in Perlite. In my test it holds 4 times the water of Hydroton so... should I extend DDoc's recco's for Hydroton intervals 3 or 4 times?

Obviously it's going to take adjustment over each run.... just trying to get to a framework to go by.

p.s. if you read this, thank you Nuggdigger for posting so much info from DDoc!

[nuggdigger]

thanx for the timely encouragement!!

when you ran your pump for one minute how much volume did you pump?

are you able to lift the columns and 'feel' the weight?

[disciple]

Quote:

Originally Posted by nuggdigger

when you ran your pump for one minute how much volume did you pump?

At the height of the top of the columns, through 1/4 line:

26 1/4 Litres or 6.5 Gallons
236 GPH (actual) vs. 1585 GPH (pump specification)

Quote:

Originally Posted by nuggdigger

are you able to lift the columns and 'feel' the weight?

Oh man that would be so sweet! Unfortunately, the perlite compresses in the bottom of the columns and retains moisture/weight. When you lift it they feel heavy/good to go but then at least 3 or 4 top sites are near dry.

I was using a 250 GPH pump and feeding each column one at a time. I found that as the columns get root bound (in veg ! ) I have to get the solution into the columns in intervals or water pours out of the third or fourth site down - bypassing the bottom 3 plants

I could run that setup for 20 seconds then shutoff. Within the next 5 to 10 mins I'd get about a half liter of runoff. About 1.5 liters in, 1/2 runs off. This was my interpretation of DDoc's run the pump till runoff.

What I failed to miss was that I probably have pockets of dry in there. Plus my little pump puts more into each column individually than the big one will in aggregate.

The best plan I have now is to dry the columns out (happening right now) then run the big pump until I get runoff so I know the columns are totally saturated. Hopefully with the slower flow I'll get less runoff than I fear.... It takes a lot of solution to feed a 1585 GPH pump running for 3+ minutes as I'm sure you're well aware of!

Then I'm going to multiply DDoc's Hydroton instructions by 4x (accounting for Perlite retaining 4x as much water as Hydroton) and watch the plants like a hawk for dry/wilt/deficiencies etc..

I'll lean more towards increasing the frequency but I want to avoid my natural tendency to overwater.

[nuggdigger]

high, i have a few DDoc quotes i could share, but i can't get to them right now as they are in the bedroom and i don't dare wake sleeping beauty...lol

so im going to step a bit off line here and dish nug style..


525 mls of water in 1850 mls of perlite is..(525/1850) roughly 28 percent moisture content by volume...
28% moisture content is not considered too wet by any means..in other words you can not overwater perlite.
keeping your plants wet all the time may not be ideal of course..

imo the biggest worry with dtw is that they will waste to much feed..
first off...your growing how many plants with how much yield, your last concern should be a few dollars worth of food..in fact it can be one of the best investments in the plants overall health..
but mainly, i feel this is due to the fact that they think they are wasting more feed then other growing systems. Take any other hydro system short of soil and you will not find less waste imo..every bubbling bucket, ebb/flow aeroponic system has its volume at least half replaced/thrown out every week or should..lol.
10-25 % runoff is much less then replacing half or all.

so you already know that the top drys out faster then the bottom..and your going to find out that those plants are the ones that are going to harsh out faster due to higher EC media from 'deeper' wet/dry cycles..this is good to know because this is where the plants will always show signs first.

so...if you really want to know how frequently to water,
you could..
give a fresh full feed at lights on..then unhook/shutoff one of the columns. continue to water the rest of the system normally, but watch the top plants in the drying out column..and when you see the very first signs of dryout..take note of how long its been since the lights on watering interval and water the column of course.
you now know how long is too long..but its a base line..and from there go 1/4 to 1/3 that time as watering interval.

now here is where it gets fun
i know you love your ppm pen, but the easiest way we can watch our plants ppm condition is in the runoff..if you find your runoff is starting to climb then you need to increase your watering volume...try to maintain feed and runoff within 200ppm for ideal plant health.

now you can establish the frequency and volume

peace

[disciple]

Quote:

Originally Posted by nuggdigger

so im going to step a bit off line here and dish nug style..

awesome! you have a lot of experience with DDoc's gear (coliseum) right?

Quote:

Originally Posted by nuggdigger

525 mls of water in 1850 mls of perlite is..(525/1850) roughly 28 percent moisture content by volume...

yes... the data I collected correlates with one of his manuals where he states Perlite holds 30% solution by volume

Quote:

Originally Posted by nuggdigger

imo the biggest worry with dtw is that they will waste to much feed..
i feel this is due to the fact that they think they are wasting more feed then other growing systems. Take any other hydro system short of soil and you will not find less waste imo..

I hear you! Today the big pump ran for about 3:28 before I got runoff. It was somewhere under 10 gallons of solution. I was running through that over the course of the day anyway when manually watering. It looks as though I'll be watering mainly once per day (maybe twice during week 4/5) and no big deal.

If I was running 72 plants of the same size (2 ft.) in a flat ebb and flow, I'd have what, a 40 - 50 gallon reservoir? and re-filling that once per week would use WAY more solution.

Quote:

Originally Posted by nuggdigger

watch the top plants in the drying out column..and when you see the very first signs of dryout..take note

any guidance on what the earliest, subtlest signs of what drying out looks like?

I've turned clones into palm trees as well as some of my earlier mother plants so I've got that down pat... but obviously serious root damage has already occurred. I see the plant drying out nicely when the leaves flatten out and look like blades. Any subtle clues when things start to go a bit too far?

Quote:

Originally Posted by nuggdigger

you now know how long is too long..but its a base line..and from there go 1/4 to 1/3 that time as watering interval.

pb said DDoc's perfect watering frequency was to sacrifice a plant (to measure) and go a quarter of the time it takes to wilt....

Always tricky as plants lift water at different rates depending on growth stage...

Quote:

Originally Posted by nuggdigger

we can watch our plants ppm condition is in the runoff..if you find your runoff is starting to climb then you need to increase your watering volume...try to maintain feed and runoff within 200ppm for ideal plant health.

another thing you just taught me.

Thank you so much Nuggdigger!!! Super appreciated.

It's a bit tricky measuring runoff with the Cage unless you get the reservoir empty. I'll try.

Other info:

I'll state that I won't be doing any recirculating operation with Perlite as it goes through the pump and clogs the barbed emitters that attach to the 1/4" line. And I wouldn't use a larger diameter line because flow would be too fast and Perlite would pour out of the plant sites all the way down the columns. I run the unit in a 4x4 tent with direct access to outside air. So far so good. No recirculating for me tho as I don't want to manage res temps.

I rigged a custom bracket to hold the 1/4 line at the top of each column. I cut up plastic risers for sink faucets from Home Depot. They come in a few different lengths and the 1/4" line slides through them freely but with a tight/snug fit. They get tuc-taped to the top of each column and then there is no pressure on the line. For one column I rigged up a "Y" shaped bracket out of the P-tex plastic risers and it holds the 1/4" line 3 or 4 cm above the hole so I can watch the fluid come out of the hose. Quick glance to check flow. I built a big lazy suzan under The Cage so I can rig it super quick.

I got a cheap moisture meter two days ago ($20 - comes with pH AND light meter ) and it actually works!! So I can spin my Cage and drive the probes in the bottom few sites of each column and know what's up. It just worked.

I threw the plants in in two stages, 3 weeks of veg with full light (600W HPS, 400W MH, 600W HPS) and the whole thing is generally overgrown. I'm now about a week and a half in (but the first few days were mainly dark so I'm behind) and full canopy. I grew them straight on but a couple of days after flip I twisted all the columns to the side.

I topped them all to get 5 or 6 mains shoots of equal height. (it worked). The bottom 36 plants had been vegging in perlite in beer cups for a month or so before they went into The Cage. They had sets of cuts taken off them as well and now in bloom have 7 - 8 viable shoots per plant. The top 36 were rooted cuts.

I'm using DDoc's guidelines for a 150 site coliseum as in that unit the plants would be on 10" centers. Sites in the cage are on 10" centers both vertically and horizontally.

At the top of the list of dumb things I've done; Planting into dry Perlite. In order to control dust I planted one at a time and poured Perlite from the site directly above. Next time I'll fill/wet all/dig out each site. I kept the cubes of the top row of plants too wet and the surrounding Perlite too dry. Stunted them a bit but fortunately didn't lose any of them.

Also, hand watering resulted in higher flow which encouraged channels to form in the columns. Now I get water coming out of some sites if I don't break up watering into intervals.

Next run plants will all be at the same stage/size, Perlite only gets watered, prune and flip earlier. Might cut back on the light as I'm overlit right now... or go from 600-400-600 to 400-400-400-400.

I wonder how many people recognize the true genius of DDoc. This thing is amazing.

[nuggdigger]

http://en.wikipedia.org/wiki/Turgor_pressure

turgor pressure is like a balloon full of air..let some out and the balloon starts to go down.
the same thing with plants..when they can't take up water..they lose plant pressure and start to wilt. I think you would see the first signs the farthest from the roots, at the top of the plant in the big fullest leaves. They will start to deflate, curl, go down, wilt, lose pressure, whatever..its loss of turgor.
watch closely for the first noticeable sign that should show on the top plant and water the column well immediately. I also suggest you shut off the lights and foliar the plants to assist them in rehydrating without stress. When the plants are back 'up' and dry the lights can go back on and i dont think there will be any sacrifices.
got some great ddoc reads on 400 vs 600 in the cage i can try to get up when i find them...

peace

[disciple]

Quote:

Originally Posted by nuggdigger

http://en.wikipedia.org/wiki/Turgor_pressure

turgor pressure.... They will start to deflate, curl, go down, wilt, lose pressure, whatever..its loss of turgor.
got some great ddoc reads on 400 vs 600 in the cage i can try to get up when i find them...

peace

Thank you for a very informative post and useful information !

Discussed the light possibilities with pb a bit before I planted... he remembered one of the better runs was 4x400... In his own experience i don't think he ran a full cage so the data collected from this work will, at the least, be a verified set of results.

I went with 2x600W HPS (because I had them) and put a 400W in between. A MH goes in there through the first bit of flower then an HPS.

I didn't know what the light coverage would be like when the the plants get up to size (I do now) so I lit to get above 3300 fc on each plant site once the cuttings showed new growth.

The 400W (even when in an array) was getting barely 2000 fc on each plant site. I wanted less stretch and thought veg would be faster. It was fast. But now that everything is up to size, I'll get more even coverage with 4x400W. In my specific situation, right now, I'm glad I have the 600W as things are way overgrown and I can use all the punch I can get as I won't be thinning too much.

At this stage, when looking at the garden as it is, 4x400W would provide better, more even coverage.

The early veg wattage doesn't seem to be as important as I thought it would be. I HAVE to try 4x250W as well. If the yield is only 10-20% lower it will be just sick! And from only 1000W.

I always expect it to take 6 months to a year to REALLY dial in a new system. I'm documenting the whole trip so there will be a post in the near future. I think people are going to freak out if the yields are somewhat close to what I expect. I'm going to do 4 or 5 runs and show all the results so a complete and realistic picture is presented instead of cherry picking and embellishing one good run.

All credit goes to pb for ongoing guidance and you, Nuggdigger, for making very useful information available.

[nuggdigger]

great!! thanx.

i dint know if you ever got a chance to see the cage and cube manual so i put it up for you..one painstaking keystroke at a time...

peace