Reservoir : stirring pump or air stone?

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KasparGrower

Well-Known Member
Hi! I got a question for ya'll: I'm a soil grower and I'm willing to jump on a coco DTW system. I've come across a few opinions about reservoir management regarding mixing and areating the solution in the reservoir. Some people say that is better to use a stirring pump set on a timer,running 15mins on and 15 off,what If I have a automatic doser for my resevoir,and it doses the nutes while the pump is off? It has a setting that delays the moment when it reads the solution's PPMs and PH,giving time to mix the nutrients,having a correct reading. Isn't it better to let the pump or the airstone run 24/7?
 
How long to run the pump depends on the volume of the re, but even small pumps can overly warm the rez if running too long

Probably no more than 5 minutes to oxygenate and mix. I recommend a deep cycle timer.
 
rkymtnman said:
i have a small waterpump, some tubing and an elbow to make a waterfall in my res. mixes and aerates at the same time
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I was reading about this method on a coco guide. They were suggesting just to run the pump a few minutes per hour and that's why I'm worried about not having the solution well mixed if my feeding controller does feed for example just after the pump goes off... I have to wait nearly an hour to have it turned back on by the timer,and in the meantime I have nutes inside not well mixed...
PhatNuggz said:
How long to run the pump depends on the volume of the re, but even small pumps can overly warm the rez if running too long

Probably no more than 5 minutes to oxygenate and mix. I recommend a deep cycle timer.
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5 mins every hour? If the answer is yes,then I still have my big interrogative about if my nutes will be well mixed...

Could I run it 24/7 if I had a chiller?
 
I have run airstones, mixing pumps and a waterfall.
All you want is the solution moving and it picks up all the O2 you need, I have a small 6 inch fan blowing constantly on the solution in the rez. It aerate's and moves the solution keeping it oxygenated and mixed.
 
gr865 said:
I have run airstones, mixing pumps and a waterfall.
All you want is the solution moving and it picks up all the O2 you need, I have a small 6 inch fan blowing constantly on the solution in the rez. It aerate's and moves the solution keeping it oxygenated and mixed.
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Some commercial growers on hydro state that they don't use airstones because 'it also brings CO2 in the water'.
I am just posting here what they are saying, so don't shoot the messenger please.

But a water pump that just mixes your nutrients and moves the surface would be sufficient in 99% of the cases.
 
Not looking to shoot anyone, :)
Just saying you don't need a pump or airstones, you just need to slightly move the water.
Think of a slow moving stream , it picks up 02, without any violent water movement.
I think I will borrow a o2 tester and check my rez when I set back up here next month.
 
Just let the pump run as I have always done. The only downside to that other than a little power usage is that it warms the nutrients up a little but with dosing pumps you need the pump to mix the solution otherwise the meter will get erroneous readings. You can also benefit from the DO that moving the water around will add.
 
Renfro said:
Just let the pump run as I have always done. The only downside to that other than a little power usage is that it warms the nutrients up a little but with dosing pumps you need the pump to mix the solution otherwise the meter will get erroneous readings. You can also benefit from the DO that moving the water around will add.
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I just have to fight the urge to take a piss every time I'm in the room and hear the soothing waterfall noise.
 
gr865 said:
Just saying you don't need a pump or airstones, you just need to slightly move the water.
Think of a slow moving stream , it picks up 02, without any violent water movement.
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Totally agree.

gr865 said:
I think I will borrow a o2 tester and check my rez when I set back up here next month.
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A friend of mine bought one.
He:"Biggest waste of money ever."
Not because it did not work.
It worked well, but just the slightest movement and the water had maximum DO all the time.
So as long as the water moves a bit, you're good. If you have enough surface of course, and not too much roots.

I wrote it before (I feel like a parrot): I visit a hydro greenhouse frequently.
They have a basin. 1.5 ft high. Rafts with different kinds of vegetables and herbs.
They only stir the water every half hour or hour for 5 minutes. They use an underwater pump. It creates just a small wrinkle in the watersurface. They have maximum DO all the time.
They also don't care about the heat that much. Even the last few days when the temperature in their greenhouse was above 40 degrees Celsius / 104 degrees Fahrenheit. The basin did not reach that temperature but it was pretty high as well, because we did not have cool nights. It was above 25 degrees Celsius / 77 degrees Fahrenheit at nights. I think if the heat would have lasted longer, they would have taken measures, because they also know that 77 degrees is a good maximum temperature for roots.
 
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Renfro said:
Just let the pump run as I have always done. The only downside to that other than a little power usage is that it warms the nutrients up a little but with dosing pumps you need the pump to mix the solution otherwise the meter will get erroneous readings. You can also benefit from the DO that moving the water around will add.
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The tank will be be outside the tent luckily...maybe during summer I will have problems...like I said,I'm just making a project... How many ºC will a pump running 24/7 gain in general from your experience?
 
Keesje said:
Totally agree.


A friend of mine bought one.
He:"Biggest waste of money ever."
Not because it did not work.
It worked well, but just the slightest movement and the water had maximum DO all the time.
So as long as the water moves a bit, you're good. If you have enough surface of course, and not too much roots.

I wrote it before (I feel like a parrot): I visit a hydro greenhouse frequently.
They have a basin. 1.5 ft high. Rafts with different kinds of vegetables and herbs.
They only stir the water every half hour or hour for 5 minutes. They use an underwater pump. It creates just a small wrinkle in the watersurface. They have maximum DO all the time.
They also don't care about the heat that much. Even the last few days when the temperature in their greenhouse was above 40 degrees Celsius / 104 degrees Fahrenheit. The basin did not reach that temperature but it was pretty high as well, because we did not have cool nights. It was above 25 degrees Celsius / 77 degrees Fahrenheit at nights. I think if the heat would have lasted longer, they would have taken measures, because they also know that 77 degrees is a good maximum temperature for roots.
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For what I've red,having coco as a substrate instead of DWC for example,res temps are more forgivable since roots don't live in water and are less affected by water in the res not being right in point... is that true?
 
KasparGrower said:
I was reading about this method on a coco guide. They were suggesting just to run the pump a few minutes per hour and that's why I'm worried about not having the solution well mixed if my feeding controller does feed for example just after the pump goes off... I have to wait nearly an hour to have it turned back on by the timer,and in the meantime I have nutes inside not well mixed...

5 mins every hour? If the answer is yes,then I still have my big interrogative about if my nutes will be well mixed...

Could I run it 24/7 if I had a chiller?
Click to expand...

Most people use too much nutes which is more likely to fall out of suspension. When using hydro ~ 50% is all that's needed.

If it's a problem for you, simply put the pump in one corner and aim it down on an angle
 
Professional facilities don't aerate DTW reservoirs. That's not where the oxygen comes from. Oftentimes the res just runs the risk of pathogens building up. Keep it still and dark; a 'dead res' to keep it from getting anything undesirable.

If your nutes are dropping out of solution there's something wrong them or how you mix them.
 
KasparGrower said:
How many ºC will a pump running 24/7 gain in general from your experience?
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it depends on how big the pump is. and your environment too. and probably a few other variables.

you could probably find a chart somewhere that would tell you how a pump of X watts warms up a reservoir of Y gallons.

DTW in coco is much more forgiving to temps than DWC

and don't mind Cheese, i don't think he grows to be honest. ask away man, that's the only way to learn.
 
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