This all began here. I read this piece about hydroponics, water temperature, cold water, water chillers and oxygen (O2, DO) a couple weeks or so ago.
Thought about it a while, Googled some stuff and posted this thread, ask for other opinion and received a few.
This cold water temperature talk, water chillers, yada, yada is 1 thing, but it looks to me like the meat of this matter is really all about vital elemental oxygen (O2) or more precisely, this is really all about trying to insure minimal safe dissolved oxygen concentration and dissolved oxygen saturation by cold nutrient water temperature.
The cold water exercise is all about trying to maintain 9 PPM – 10 PPM @ 100% DO Saturation (safe DO) 24/7 for 3 months during a growing season. At least that the numbers everyone lloves to quote from the internet DO Charts. The DO chart numbers is never that same as the actual DO numbers revealed in real time DO test in functional grows and different stages of plant/root maturity and beneficial microbial colony maturity. Both eco system being aerobic, both eco system requiring and consume more O2 as they mature and grow.
So this cold water is really all about elemental O2 (the most vital element dissolved in nutrient water), not the side show… water temperature or elemental nitrogen and elemental trace gases in ambient air that compose 79.1 % of the gases in air, air bubblers, waterfalls, water jets, water pumps, water chillers, air compressors or air ventures entraining ambient air into water pumps.
Is the logic? - If you guessed that you need more oxygen because your roots are sick, dying and rotting or you think you caught a fungal infection somehow; you guess the cause of this problem is that your DO might be too low so you want to increase the DO stop the root suffocation. So you can either make the nutrient water colder or add more air, higher waterfall or both to be on the safe side of the DO chart to fix the low DO problem or kill the fungal infestation or trash the sick crop and try it again.
And, if you really want the absolute best oxygenation for DWC or FDWC, then they say that 13 PPM DO Concentration @ 100% DO Saturation is the best, that’s the best DO money can buy. But, that same DO Chart that every water chiller salesman quotes from as well as everyone else quotes says you can achieve this 13 PPM DO only with chilled, cold 50 F nutrient water. And that would probably require a $800 water chiller for a continuous 50 F chill job like this.
The DO would be great, but, would this cold nutrient water negatively affect dissolved gas diffusion, water and nutrient diffusion in the roots and microbes cells in DWC/RDWC conditions? Hmmm… ?
Personally, I would prefer the optimal, continuous 13 PPM DO in constant 77 F nutrient water because warmer water always = higher root/plant metabolism, healthier roots and most important – a faster grow-out time to harvest. The 13 PPM DO guarantees there will be no low oxygen problems in the nutrient water.
But, I understand that you can’t do this by guessing. Like pH and EC testing, you must test the DO and then adjust the DO up or down. That’s not adjusting the nutrient temperature up or down although there is a relationship between water temperature, salinity, gas partial pressure and gas % concentration
HYDROPONICS
Water temperature ranges in hydroponic systems
Posted on August 16, 2012 by campo cultivator
http://www.growersguidetocannabis.com/water-temperature-ranges-hydroponics/
(so why do cannabis growers use hydroponic systems? Quite simply because given the right conditions, hydroponics enable bigger, quicker results than any others. Hydroponic grows “mainline” the nutrients, water and oxygen direct to where the plants can make use of them: the root system).
What is the ideal hydroponic reservoir temperature?
So why am I talking about oxygen when the subject matter is water temperature?
The temperature of water and its oxygen content are closely related, and the temperature of the solution needs to be fairly closely monitored in order to maintain dissolved oxygen levels. At low water temperatures, the plants go into shock, but as the temperature rises in the tank the solution loses the percentage ratio of its oxygen content. Here are some figures:
tank temperature & % of oxygen in the solution (ppm)
10ºc (50ºf) 13 ppm
[EXCELLENT DO CONCENTRATION RANGE – 100% DO SATURATION]
20ºc (68ºf) 9-10 ppm [OPTIMAL SAFE DO CONCENTRATION RANGE – 100% DO SATURATION]
30º (86ºf) 7 ppm
[7 PPM DO CONCENTRATION RANGE – 100% DO SATURATION KILLS ROOTS – ROOTS SUFFOCATE, DIE AND PYTHIUM OUTBREAK IS PREDICTABLE]
As you can see the oxygen content in the resolution approximately halves for every 10ºc rise in solution temperatures.
ok got that!
**In easy terms, ideal temps are between 18 and 20 ºc [
64 F – 68 F] and if your water temps are anywhere near 25 -30ºc
[77 F – 86 F] then the oxygen levels can be as much as half of the desired levels.
BUT
As a direct result of the water temperature being at higher temps the plants will need more oxygen at the roots so the problem is almost squared and there is 25-40 % less oxygen in the solution and the plants will need double the amount than normal.
In real terms the effect is that the oxygen level in the solution is only at 25 % of the desired levels and you can chuck as much light or feeds at them as you like but if they are only running at 25% of the required dissolved oxygen levels then this is hardly conducive to happy healthy growth is it?
Some of the results of low oxygen levels in the rez tank are:
1. roots are unable to work effectively, leading to:
2. a build up of toxins meaning that the plant will be unable to take up the water and feeds needed for healthy growth
3. The whole plant begins to deteriorate as photosynthesis and carbohydrate rates slow leading to wilting.
4. Leaf damage and root die-back. Ethylene is released and causes a toxic overdose and the roots fail.
And all of the above cause ideal conditions (especially in warm water) for every hydroponic growers worst enemy: PYTHIUM
[NOW COMES THIS WRITERS PIVOT FROM OXYGENATION TO WATER TEMPERATURE AND THE HARD SELL FOR WATER CHILLERS!]
**** So of course the real solution to high water temperatures in a hydroponic reservoir is a water chiller. ****
We tried inserting bottles of ice water into the res tank but despite dedicating a small chest freezer to the production of ice, found it almost impossible to sufficiently and consistently cool our water (warmed by hot sunshine on the pipes outside).
I
ts yet another expensive piece of kit to add to the grow room, but if you are growing hydroponically in an environment where water temperature rises either due to external environment (like ours) or internal environment (the tank is warmed by heat thrown out by your HPS),
then a water chiller IS be the only solution.[
BUY A WATER CHILLER BECAUSE COLD WATER TEMPERATURE IS THE ONLY SOLUTION THAT WILL INSURE SAFE OXYGENATION AND PREVENTING LOW OXYGEN INSULTS, ROOT SUFFOCATION,FUNGAL OUTBREAKS, FAILURE, YADA, YADA, YADA.]
It is well documented in the horticulture scientific literature that in DWC/RDWC hydroponic farming that low dissolved oxygen in circulating nutrient water creates the ideal conditions predisposing root suffocation, sick roots, root death, root decay, root rot which is the required condition inviting invasions and colonization from fungal opportunist like Pythium and other fungal outbreaks. Pythium does not thrive and colonize in oxygen rich res water containing healthy roots and healthy beneficial aerobic microbes.
And most dudes really believe that a $300-$400 water chiller IS THE ONLY SOLUTION there is in the 21st century that will insure safe oxygenation (9 PPM – 13 PPM DO)… “Is Nothing Sacred?”
***How many of you DWC/RDWC dudes have ever actually tested your nutrient water temperature with a thermometer, pH, EC with a pH/EC meter?
***How many of you DWC/RDWC dudes have ever actually tested your nutrient DO Concentration and DO Saturation with a DO Meter?
Hmmm… even the most armature dudes should know that if you don’t test your nutrient water in DWC/RDWC you’re doing no more than guessing, hoping, preying at best.