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hawksapprentice said:
I would switch out the water.

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Magash said:
Add more water till the ec drops back into range then adjust the ph. Change out the solution every week and check your ec every few days.(along with your ph levels) The plants will always use water faster then nutrients.

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Magash said:
I meant it the way I originally posted it not the way Hawk fixed it.

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hawksapprentice said:
And I meant it the way I fixed it

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Well which one is it?
I've been under the assumption it was average about once a week.

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hawksapprentice said:
And I meant it the way I fixed it

Expensive?  Are you using bottled water or some shit?

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hawksapprentice said:
Bigger bottles are cheaper.  If you are doing hydro I would just start buying the bigger ones.

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DonkeyDong69 said:
With a water filter, a GH biofilter, air stone, cascade aerator and a water cooler now installed, I think I can go even longer in between changes. Probably unlikely, but maybe even a month given they don't drink all the nutes by then. I mean if I have enough things keeping the water clean and roots happy, shouldn't I be able to go longer?

I'm under the impression that with a DWC, you don't necessarily have to change your water until your final flush given you keep topping it with a balanced nutrient solution that keeps the water at the same concentration. I don't see why you couldn't do the same with any recirculating system.

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Dude...not at all. Plants are like humans, they eat their nutrients, "digest" and use them to make fruit or flowers, and excess is excreted back into the soil. The molecules you add in your reservoir are not the same molecules the plant uses. Just look up photosynthesis and the calvin cycle and electeon transport chain before i start a chemistry rant.

Some of the nutes are taken up, but from that nutrient that is absorbed, some is released back out from the roots. If the plant took every last bit of nutrient then your ppms would decrease over time...however this is NOT the case. The plant is shitting nutrient waste back into the soil. These excess sugars and carbohydrates form a symbiotic relation with mychorrizae and bacterias that allow nutrients to be better absorbed.  BUT THATS FOR SOIL!

In a hydro system there are no bacterias to break anything down. The waste from the plant is excreted back into the water and overtime can and will build up to toxic levels...throwing off any readings of pH or ppm or EC...and eventually reaching high enough toxicity to kill your plant.

Its like drowning in its own shit...so change your fuckin reservoir...lets not even start talking about salt build up.

Fuck man...never changing your res? For reals?

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hawksapprentice said:
That's fine, don't listen to people who have been doing this a long time.  I don't know why I try anymore.

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hawksapprentice said:
That's fine, don't listen to people who have been doing this a long time.  I don't know why I try anymore.

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I guess I don't have any idea either - although I appreciate the effort; I do still post here.

It's nothing personal. Other people who have been doing this a long time also have said you don't necessarily have to switch out every week. I guess this is nonsense to you.

It's not like I'm not taking your advice either; really, I'm just positing the idea that maybe - just maybe - with the parameters I have in place, perhaps I can go little longer than a week before a complete switch without much issue. If anything, this is merely for discussion sake - and why not?

I mean maybe if you came here and said "Dude, I've tried basically the same stuff you have in your setup. It won't make a difference. I've never seen any of these things make a difference in recirculating systems. Changing out every week in practice is the best thing to do." Then yeah, but I think you threw me your advice a little bit too quickly.

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SmokeSomeHash said:
Fuck man...never changing your res? For reals?

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SmokeSomeHash said:
Some of the nutes are taken up, but from that nutrient that is absorbed, some is released back out from the roots. If the plant took every last bit of nutrient then your ppms would decrease over time...however this is NOT the case. The plant is shitting nutrient waste back into the soil. These excess sugars and carbohydrates form a symbiotic relation with mychorrizae and bacterias that allow nutrients to be better absorbed.  BUT THATS FOR SOIL!

In a hydro system there are no bacterias to break anything down. The waste from the plant is excreted back into the water and overtime can and will build up to toxic levels...throwing off any readings of pH or ppm or EC...and eventually reaching high enough toxicity to kill your plant.

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You make a fair and interesting point - I sort of knew all of that already, but you seem to be much more knowledgeable in the field; however, it's not clear to me you know what every component in my reservoir (of which I basically listed) does - so I don't know how relevant your response is. For instance, the biofilter and it's accompanying subculture bacteria basically do as you've described, what hydro systems lack compared to soil, and more I think.

I mean, sometimes I'm a flaming retard, and I'm not ashamed to admit it, but I'm quite inquisitive and I'm not terrible at asking questions either: are the dynamics of recirculating hydro systems so well understood, that any modifiable parameter can be overlooked? Is the one and only thing to do, to keep your water and roots healthy, to switch out everything in your reservoir every week? Surely there are ways of keeping the water cleaner and in check for longer? Googling for this stuff will give you no straight answers, even with some chemistry under your belt.

Thus, I don't even know if there is any constructive value to be extracted from such discussion - the "take my advice or leave it" approach is not discussion; there is nothing convincing about it when juxtapositioned with what I have read, seen, hypothesized and heard. That doesn't mean it doesn't hold any weight, but it is a very normative argument - Sure! Your plants should have fresh nutes and fresh clean water every single god damn day. Of course! Advice is duly noted.



....but what about some of those DWC people that don't switch out their water that often?

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DonkeyDong69 said:

I'm under the impression that with a DWC, you don't necessarily have to change your water until your final flush given you keep topping it with a balanced nutrient solution that keeps the water at the same concentration. I don't see why you couldn't do the same with any recirculating system.

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SmokeSomeHash said:
As i also mentioned...some people over fill their rez and go weeks between changes.

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DonkeyDong69 said:

I'm under the impression that with a DWC, you don't necessarily have to change your water until your final flush given you keep topping it with a balanced nutrient solution that keeps the water at the same concentration. I don't see why you couldn't do the same with any recirculating system.

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Thats where i got the impression. That makes it seem like you won't even empty and refill between veg and bloom.

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hawksapprentice said:
You guys are looking at this the wrong way.  Your plants use different amounts of nutrients at different times.  If all you do is continue to top off with extra nutrient water, you are going to have higher levels of certain nutrients than others.  The longer you go, the worse this becomes.


Changing out your reservoir on a regular basis helps you keep a balanced NPK ratio, as well as the micro-nutrients.  This in turn will help keep your plants healthier and in the end a bigger yield, with a better end product.


These filters are not going to address this issue.

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Magash said:
Fucking what the fuck.

Every week top off the res. Once every two weeks change it. That's all there is to it. Why all the trouble to make things a pain in the ass to save what amounts to pennies. (Myself I go with large reservoirs so I can get away with a change every 3 to 4 weeks if I need to). Now the bio-filter thing is interesting and if your wanting to go organic to help save the world then that's awesome but if your doing it cause you think the taste or smell or whatever is better then your dead wrong.

Interesting subject just seems like a way to make a easy way to grow a pain in the ass. 


By the way the only Fox Farm nutrient that is organic is the Big Bloom. Grow Big and Tiger Bloom are not organic.

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Magash said:

By the way the only Fox Farm nutrient that is organic is the Big Bloom. Grow Big and Tiger Bloom are not organic.

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SmokeSomeHash said:
The grow big and tiger are mainly synthetic but they also have organic stuff such as earthworm castings.

Wouldnt that be filtered out by the filter?

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SmokeSomeHash said:
I dunno man iust try it and find out i guess.

As for water chillers...they can help you a lot but not with the EC.

Theres a commercial hydroponic iceburg lettuce farm in south texas where they grow in greenhouses under the sun but the water is cold to the touch.

Even though the temps get high enough to cause bolting, the low root zone temps keep the plant nice and healthy through extreme heat with no bolting.

Lettuce is a very heat intolerant crop and without the water chiller they wouldnt grow. In normal temps one may not be necessary but on either side of the extreme a water chiller, or reservoir heater can be a great help.

I would assume bacterias would grow slower in colder water similar to how refridgerating food works but i dunno...

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Well, I know that the biofilter is advertised as something that can compensate for high environmental temperatures. This image is from the biofilter product page.


They're basically saying "look how high temperatures can get - and they're still alive!" I understand a lot of root pathogens grow at higher temperatures and the subculture fights this, but high temperatures aren't really a problem in my setup. So I question whether the culture actually has that much benefit... and if anything it's probably very sluggish because of the temperature as you said, and perhaps also finding it difficult to survive because of that.

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SmokeSomeHash said:
Just set up all your stuff and do a grow log!

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Yessir! My grow log. I'll get an update in there probably tomorrow.

Here's some photos of the irrigation.



In total: 3 separate pumps, 1 airstone & 1 air pump, 500ltr Aquarium Chiller, 1 inline screen filter, a bio-filter with live culture and a cascade. Tank capacity: 100ltr. Overkill?

Here's what's going on above:



Aside from heat stress near the light (working on getting a better fan) they seem to be doing ok..