DTW vs recirculating

  • Thread starter klapperkaak
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klapperkaak

klapperkaak

2
3
Hi everyone,

I know this topic has been explored already but I would love to see some more opinions/experience/insight (basically any input) on the subject.

I have run both DTW and recirculating drip on coco and my best yields have actually been with recirculating! I am now running an automated reservoir for DTW wich is amazing but I'm still torn.

The thing is, I'm using small 6 liter troughs in a gutter and it becomes a real pain to keep the EC stable and at the end of the grow. Especially when I have 4 plants per trough.. I'm doing 20 irrigation cycles a day building up multiple minutes each cycle. Usually I get 20% drain, or at least I try, sometimes it's more sometimes it's less, but the EC on the drain is always much higher at the end of the grow. The amound of nutrients I would drain would be a little bit rediculous if I really wanted to pin down my EC, that would go towards 50% drain.. The end result is that at the end of the grow the EC inside the troughs is sometimes over 3, thats more then 2000 ppm! Ofcourse I tried lowering EC but then I get less explosive growth, and I get some chlorosis, I just can't seem to find that sweet spot.
The obvious solution is ofc to increase the size of the container but I don't want to redesign my system. I really like the troughs because they dont take alot of height.

I think the big advantage of recirculating is that you can really keep EC rock solid. You can feed more because the EC will build up less. You can even get away with feeding less if you increase the amount of watering cycles. When the plants are properly rooted I would set very long drip cycles so that the total volume of the trough is circulated through multiple times. That means the pump was running at least 4 hours a day, and that might seem excessive but I have never seen plants grow like that... I did some reading on trials done in commercial greenhouses and it seems that pretty much all plants prefer a stable EC of less then 2, and any more will reduce yield in pretty much any plant. A stable EC throughout the grow improves yield significantly, and plants are more negatively affected by high EC while low EC is tolerated much better.

Also, I never did a reservoir change. The first time I did get some minor calcium deficiency at the very end of the grow. Easily remedied by adding some extra calcium nitrate. Lowering RH can also help increase Ca uptake. I'm actually considering buying a specialised calcium ppm tester that would be ideal, but its really expensive.

You often hear people say that the mineral balance goes out of whack when recirculating but plants have actually evolved to become tolerant to that. They have to because soil never contains the same amount of minerals either. The real problem is pH drift, which causes calcium to crystallise out of solution, and buildup of toxic micro nutrients, such as copper, but this takes a long time. Luckily for us though, our favourite plant is very fast so you can get away with just 1 reservoir change when switching from veg to flower. And I didn't even do that.
When plants absorb nitrogen, or any nutrient for that matter it is exchanged with a corresponding ion. So NO3- is exchanged for OH-, so nitrogen uptake will make the nutrient solution more basic and NH3+ will be exchanged for H+, so ammonium uptake will make the solution more acidic. A good hydro nutrient will contain a little bit of ammonia so that pH is more stable. In order to offset this pH shift I use a pH controller that slowly supplies nitric acid into my reservoir.

Maybe I just need more practice dialing in the DTW setup so that I dont get so much salt buildup, but in that case I guess that also means recirculating is more forgiving in that respect. But pH and EC will have to be monitored much more closely.

To take recirculation to the next level a pH controller is essential so pH stays solid, an automatic top-up system is nice so that fresh nutrients are always supplied, and periodically add extra calcium nitrate just to be sure.

If anyone is interested I could make some pic of my automated tank, could be inspiring for some people.

Anyways let me know what you prefer and why! Pros and cons, do's and don'ts, hows and whys I wanna know it all!
 
4TREESCANNABIS

4TREESCANNABIS

99
33
Hi everyone,

I know this topic has been explored already but I would love to see some more opinions/experience/insight (basically any input) on the subject.

I have run both DTW and recirculating drip on coco and my best yields have actually been with recirculating! I am now running an automated reservoir for DTW wich is amazing but I'm still torn.

The thing is, I'm using small 6 liter troughs in a gutter and it becomes a real pain to keep the EC stable and at the end of the grow. Especially when I have 4 plants per trough.. I'm doing 20 irrigation cycles a day building up multiple minutes each cycle. Usually I get 20% drain, or at least I try, sometimes it's more sometimes it's less, but the EC on the drain is always much higher at the end of the grow. The amound of nutrients I would drain would be a little bit rediculous if I really wanted to pin down my EC, that would go towards 50% drain.. The end result is that at the end of the grow the EC inside the troughs is sometimes over 3, thats more then 2000 ppm! Ofcourse I tried lowering EC but then I get less explosive growth, and I get some chlorosis, I just can't seem to find that sweet spot.
The obvious solution is ofc to increase the size of the container but I don't want to redesign my system. I really like the troughs because they dont take alot of height.

I think the big advantage of recirculating is that you can really keep EC rock solid. You can feed more because the EC will build up less. You can even get away with feeding less if you increase the amount of watering cycles. When the plants are properly rooted I would set very long drip cycles so that the total volume of the trough is circulated through multiple times. That means the pump was running at least 4 hours a day, and that might seem excessive but I have never seen plants grow like that... I did some reading on trials done in commercial greenhouses and it seems that pretty much all plants prefer a stable EC of less then 2, and any more will reduce yield in pretty much any plant. A stable EC throughout the grow improves yield significantly, and plants are more negatively affected by high EC while low EC is tolerated much better.

Also, I never did a reservoir change. The first time I did get some minor calcium deficiency at the very end of the grow. Easily remedied by adding some extra calcium nitrate. Lowering RH can also help increase Ca uptake. I'm actually considering buying a specialised calcium ppm tester that would be ideal, but its really expensive.

You often hear people say that the mineral balance goes out of whack when recirculating but plants have actually evolved to become tolerant to that. They have to because soil never contains the same amount of minerals either. The real problem is pH drift, which causes calcium to crystallise out of solution, and buildup of toxic micro nutrients, such as copper, but this takes a long time. Luckily for us though, our favourite plant is very fast so you can get away with just 1 reservoir change when switching from veg to flower. And I didn't even do that.
When plants absorb nitrogen, or any nutrient for that matter it is exchanged with a corresponding ion. So NO3- is exchanged for OH-, so nitrogen uptake will make the nutrient solution more basic and NH3+ will be exchanged for H+, so ammonium uptake will make the solution more acidic. A good hydro nutrient will contain a little bit of ammonia so that pH is more stable. In order to offset this pH shift I use a pH controller that slowly supplies nitric acid into my reservoir.

Maybe I just need more practice dialing in the DTW setup so that I dont get so much salt buildup, but in that case I guess that also means recirculating is more forgiving in that respect. But pH and EC will have to be monitored much more closely.

To take recirculation to the next level a pH controller is essential so pH stays solid, an automatic top-up system is nice so that fresh nutrients are always supplied, and periodically add extra calcium nitrate just to be sure.

If anyone is interested I could make some pic of my automated tank, could be inspiring for some people.

Anyways let me know what you prefer and why! Pros and cons, do's and don'ts, hows and whys I wanna know it all!


Drain to waste is the easiest step into hydroponics from someone coming from soil and will require the least amount of equipment, maintenance, and knowledge. The pH and PPM you set main feed tanks to is exactly what it is when its fed to the plant and the runoff that travels under light creating bacteria etc travels out of the grow room. This means the system does not need to be as light-proof, water chillers are not needed, etc.

Recirculating systems, on the other hand, are very great for speed of growth, water, and nutrient conservation but take more upfront costs in equipment such as fertigation controls, water chillers, aeration, and light proofing the entire system.

I personally don't like recirculating anything in hydroponics unless it is completely light proof and in a medium that doesn't hold water or nutrients.
This will give you the best growth as nothing will be building up or creating bacteria in the light.

Some systems that work great on a 24hr recirculation are: Deep Water Culture (DWC), Aeroponics, Fogponics, Float Systems, and Aquaponics

Any other questions im happy to answer.
 
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