pugnacious
Active member
Was checking out a dutch leach trays last night for a possible DTW hydro system i might be using. I never seen them used on icmag or in person. Does anyone have any links to some good DTW grows?
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Drain to waste system
- Thread starter pugnacious
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pugnacious
Active member
Some specific questions on a DTW rockwool system.
1.) What size and type of pump is used?
2.) How long are they fed?
3.) How often?
1.) What size and type of pump is used?
2.) How long are they fed?
3.) How often?
the questions you are asking aren't relevant....they are, but they aren't. I'll explain.
Pump size, feed duration and frequency are determined by your plants and the stage in which they are in. These variable will change throughout your growing cycle. You will need to feed more and more frequently as the plants mature and they require more moisture/nutrition.
Think of DTW as you would a recirculating system. The only difference is that you aren't feeding your plants recycled nutrient. In a recirculating system, you are recapturing nutrient rich water and reusing it with each irrigation. With drain to waste you are feeding fresh solution with every irrigation.
Recirculating systems are more efficient when in it comes to water and nutrient consumption. DTW systems are more ideal, because you are giving your plants the 'perfect' mix of nutrition with every irrigation.
Remember, in a recirculating system, with every irrigation your plants are taking what they want from the nutrient rich solution and leaving behind what they don't want or don't need at the time. SOOO, with every irrigation or feeding your remaining reservoir nutrient levels are different from when they started. This can cause an imbalance in nutrients in your solution over time. And if you continue to feed your plants an imbalanced nutrient solution they have a higher likelihood of developing deficiencies and toxicities. This can be minimized with frequent reservoir changes.
Most commercial growers using rockwool, use dtw systems, to limit potential nutrient and chemical imbalances in their nutrient tanks, this minimizes pH drifts and potential problems associated with that as well.
Pump size, feed duration and frequency are determined by your plants and the stage in which they are in. These variable will change throughout your growing cycle. You will need to feed more and more frequently as the plants mature and they require more moisture/nutrition.
Think of DTW as you would a recirculating system. The only difference is that you aren't feeding your plants recycled nutrient. In a recirculating system, you are recapturing nutrient rich water and reusing it with each irrigation. With drain to waste you are feeding fresh solution with every irrigation.
Recirculating systems are more efficient when in it comes to water and nutrient consumption. DTW systems are more ideal, because you are giving your plants the 'perfect' mix of nutrition with every irrigation.
Remember, in a recirculating system, with every irrigation your plants are taking what they want from the nutrient rich solution and leaving behind what they don't want or don't need at the time. SOOO, with every irrigation or feeding your remaining reservoir nutrient levels are different from when they started. This can cause an imbalance in nutrients in your solution over time. And if you continue to feed your plants an imbalanced nutrient solution they have a higher likelihood of developing deficiencies and toxicities. This can be minimized with frequent reservoir changes.
Most commercial growers using rockwool, use dtw systems, to limit potential nutrient and chemical imbalances in their nutrient tanks, this minimizes pH drifts and potential problems associated with that as well.
pugnacious
Active member
First. I want to thank you for your reply.
So in a nut shell a DTW system is ran like a ebb and flood table. So probably a few times a day feeding is necessary depending on the ppm lvl and stage of the plants.
I dont know why I couldnt connect the dots. Now I cant wait to hit these trays.
So in a nut shell a DTW system is ran like a ebb and flood table. So probably a few times a day feeding is necessary depending on the ppm lvl and stage of the plants.
I dont know why I couldnt connect the dots. Now I cant wait to hit these trays.
you are correct. Treat as if you would an ebb n flow or drip recirculating system in watering frequency.
Keep in mind that there are positives and negatives to both approaches. The negatives to DTW is water and nutrient waste. There are still good nutes you are throwing away by running to waste. The positives are that you are keenly aware of exactly what your plants are getting with each irrigation cycle.
With recirculating systems some of the positives are getting the most out of your nutrient and water consumption. A negative would be the possibility of imbalances over time if you aren't on top of your reservoir changes and maintenance.
There are more pros and cons than this that you will discover throughout your learning process. Keep asking the questions....
Keep in mind that there are positives and negatives to both approaches. The negatives to DTW is water and nutrient waste. There are still good nutes you are throwing away by running to waste. The positives are that you are keenly aware of exactly what your plants are getting with each irrigation cycle.
With recirculating systems some of the positives are getting the most out of your nutrient and water consumption. A negative would be the possibility of imbalances over time if you aren't on top of your reservoir changes and maintenance.
There are more pros and cons than this that you will discover throughout your learning process. Keep asking the questions....
irrigation frequency is an independent variable to ppm levels.
Irrigation frequency is determined by your plants water intake needs, and media water retention capacity. Your ppm levels are determined by your environment you've created as well as your specific plants needs.
For example...we could be growing the exact same cutting. Let's say for arguments sake that you have 8000 watts of light, with co2 supplementation and a near perfect growing environment. I on the other hand am growing under a 250 watt light in a closet with minimal air exchange an improper ambient air conditions. Your plant would need more food to keep up with the demand created by your light and co2 and such. I would need to feed significantly less than you because my plants growth rates are bottle necked because of the conditions i've provided...
We would probably have the same watering schedule...but your ppm levels would need to be higher while mine would need to be lower.
Remember, feeding your plants more (ie. higher ppm levels) doesn't make your plants grow faster. It's the light and co2 and environmental factors along with the genetics that determine plant growth. All you can do with ppm levels is keep it consistent with your plants, and your growing environments needs. Hope that makes sense....
Irrigation frequency is determined by your plants water intake needs, and media water retention capacity. Your ppm levels are determined by your environment you've created as well as your specific plants needs.
For example...we could be growing the exact same cutting. Let's say for arguments sake that you have 8000 watts of light, with co2 supplementation and a near perfect growing environment. I on the other hand am growing under a 250 watt light in a closet with minimal air exchange an improper ambient air conditions. Your plant would need more food to keep up with the demand created by your light and co2 and such. I would need to feed significantly less than you because my plants growth rates are bottle necked because of the conditions i've provided...
We would probably have the same watering schedule...but your ppm levels would need to be higher while mine would need to be lower.
Remember, feeding your plants more (ie. higher ppm levels) doesn't make your plants grow faster. It's the light and co2 and environmental factors along with the genetics that determine plant growth. All you can do with ppm levels is keep it consistent with your plants, and your growing environments needs. Hope that makes sense....
pugnacious
Active member
Its definitely going to be a learning experience. I wonder how much more Im going to be spending on nutes and water compared to a ebb&flood system.
water consumption on the hobby level is minscule. So is nutrient consumption compared to value of our product. Without crunching numbers...I'd say you would use easily 2-3 times as much nutrient in a dtw as you would a recirculating system. Just a guess....don't know for sure.
However, the increased potential production from your plants recieving a perfect mix of nutrition and water with each feeding might....probably will offset the additional cost of nutrients. Base nutes run anywhere from 20-50 for a set of quarts...that's a gram to an eighth of final weight....easily offset by additional production.
However, the increased potential production from your plants recieving a perfect mix of nutrition and water with each feeding might....probably will offset the additional cost of nutrients. Base nutes run anywhere from 20-50 for a set of quarts...that's a gram to an eighth of final weight....easily offset by additional production.
you'll notice the people who run to waste don't complain about ph problems...
..............
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Ca++
Well-known member
DTW waste is about 15%, but I was often wasting 30% to keep on top of pH using coco.
Some recirculating systems such as F&D have a minimum water volume they can run with. So at tank change, that is your waste. How often you change is a different matter. With some just topping up for months, and others dropping the tank out every week.
I have no doubt F&D / E&F beats DTW, if you can accommodate the tank sizes needed. The feed might be fresher with DTW but F&D can be near aeroponics. If you start looking at mass balance ideals, and nutrient management based on individual element monitoring, the idea of a fresh feed starts to have less meaning.
I really dislike dripping into rockwool. To me, it's a 20% loss before even starting. It's been superceded by coco. Feed costs are not even on my mind. I would avoid dtw rw like the plague. It's just sodden. That is why it died in the 90s along with NFT.
There are sooo many ways to collect the waste, and really non of it matters. It's just whatever is convienient. If it's trays that fit framework, because you want to just assemble a premanufactured system, that's cool. Many can be wheeled around, and the trays lifted out onto stands, that wheel off into cleaning areas. Or you can just work pots that leach out onto a floor with drainage channels like your driveway. Many people like corrigated roofing sheet, which is designed to catch falling water and route it away. Or like myself, non of the above. Ceiling height is often the limiting factor.
Some recirculating systems such as F&D have a minimum water volume they can run with. So at tank change, that is your waste. How often you change is a different matter. With some just topping up for months, and others dropping the tank out every week.
I have no doubt F&D / E&F beats DTW, if you can accommodate the tank sizes needed. The feed might be fresher with DTW but F&D can be near aeroponics. If you start looking at mass balance ideals, and nutrient management based on individual element monitoring, the idea of a fresh feed starts to have less meaning.
I really dislike dripping into rockwool. To me, it's a 20% loss before even starting. It's been superceded by coco. Feed costs are not even on my mind. I would avoid dtw rw like the plague. It's just sodden. That is why it died in the 90s along with NFT.
There are sooo many ways to collect the waste, and really non of it matters. It's just whatever is convienient. If it's trays that fit framework, because you want to just assemble a premanufactured system, that's cool. Many can be wheeled around, and the trays lifted out onto stands, that wheel off into cleaning areas. Or you can just work pots that leach out onto a floor with drainage channels like your driveway. Many people like corrigated roofing sheet, which is designed to catch falling water and route it away. Or like myself, non of the above. Ceiling height is often the limiting factor.
Fuck yeah! That dinosaur shit is obsolete and uncool - see my current grow for definitive proof. No one does that kind of thing these days, whether spending millions or growing in a tent.
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Hiddenjems
Well-known member
This. With flood and drain containers filled with expanded clay I get a nft type hydro. The table never gets dry during lights on. I flood every 45 minutes or hour just long enough to fill the table.
I’ve run dwc and high pressure aero. I always come back to flood and drain tables.
Ca++
Well-known member
Newbies. Not even two years experience, and don't know any other growers. They have not had time to recognise the problems yet.Fuck yeah! That dinosaur shit is obsolete and uncool - see my current grow for definitive proof. No one does that kind of thing these days, whether spending millions or growing in a tent.
Legal cannabis: Inside the UK's first fully licensed facility
The BBC is given exclusive access inside the UK's first fully approved and licensed medical cannabis facility.
It's not easy when the plants look great and the problems consist of molding in the fat heavy buds, and supporting all their weight in the last month.
Hiddenjems
Well-known member
There are pros and cons to every method. Do any of them long enough and the cons have you at least trying other methods.
