jijiandfarmgang
Well-Known Member
FAQ
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Whats the best sterilizing agent for a hydroponics reservoir?
There are many ways to have a sterile reservoir, chlorine, H2O2, Ozone, etc. All have pros and cons. I'm going to focus on Chlorine because its easy to measure, cheap and effective.
I have root rot/ pathogen problem how much extra chlorine should I add?
Chlorine is best used to prevent pathogen outbreaks not to treat them.
Is running a sterile res better than using beneficial bacteria?
I'm no aficionado on bennies, so I couldn't say. However some claim that they tried running sterile and it didn't work for them; bennies being the only thing that works. I doubt they were properly using a sterile reservoir in the first place but who knows.
If I don't have a sterile reservoir or use beneficial bacteria will I get a root rot/pathogen problem?
Not necessarily. Many people claim to use neither and have great results. If you focus on using plenty of dissolved oxygen, keep nutrient solution at a reasonable temperature, use a relatively low EC, do solution change outs at reasonable intervals, keep organic material, nutrients and additives out of nutrient solution, and keep away light leaks.......you should be fine too.
However, I do always recommend using bleach as a sterilizing agent in between grows.
I heard chlorine is bad for plants?
Not necessarily. Most plants can tolerate up to 5 ppm of chlorine.
This is great, I found an old gallon of bleach underneath my kitchen sink. This should be enough to sterilize my reservoir for years right?
If your going to use bleach, its better to use newer bleach. After a year the composition has drastically changed.
My tap water has chloramine, its the same as chlorine except it doesn't dissipate as fast right?
Not really. Chloramine is not as effective as oxidizing as chlorine.
I heard all I need to do is add 1ppm chlorine per gallon every 2 days to my reservoir and I'm set.
Not really. FYI most municipal tap water that is disinfected with chlorine has .5 to 1ppm of chlorine. The EPA allows for up to 4ppm. This doesn't mean its going to be ideal for your hydroponic system. Read below.
Jiji, how did you become an expert on sterile hydroponics?
I'm not, and don't claim to be. Most of this info is just ripped off the net, I'll try to cite my sources. I'm just trying to gather facts and disseminate information to the hydro community.
How a sterile res works with chlorine as an oxidizer
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Microbes are surrounded by a cell membrane surrounded by structural proteins. These proteins maintain their shape. When a strong oxidizer is present such as chlorine, proteins are released and they are accepted by the oxidizer. When the cell loses its proteins it loses its structure and disintegrates.
The higher the ORP (oxidization Reduction Potential) the faster proteins are lost from cells.
When you add chlorine in the water, thats called the Total Chlorine. Some of the Chlorine will bind with dirt, debris, plant etc., this is called Combined Chlorine. Combined chlorine is chlorine that is lost for disinfection. The rest is called FREE CHLORINE. Free Chlorine is in two forms, HOCL (Hypochlourus acid) and -OCL (Hypochlorite ion). HOCL is the only form that is active for oxidation. HOCL and -OCL change in proportion dependant on PH. Free Chlorine is about 95% HOCL at a PH of 6.5 and almost a 100% at PH 6.0. HOCL can generally easily be measured using a redox/orp meter.
To know the disinfection properties, you need to know the ORP. ORP is measured in mV. Different oxidizers have different strengths. For chlorine a general accepted ORP value in hydroponics is 600mV to 750mV. This can vary on biological load, but probably closer to 600mV is better as achieving 750mV or above requires a fair amount of chlorine.
I use calcium hypochlorite, in the form of pool shock. Its extremely cheap and easy to find. I make a liquid batch so that 1 ml when added to a gallon of water will equal 1 ppm chlorine. Dose as necessary usually every two days.
Further reading and sources:
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http://www.hannainst.com/literature/Sanitation - UConn results.pdf
http://www.hannainst.com/literature/lithydro_sani_sys.pdf
http://water.epa.gov/drink/contaminants/basicinformation/disinfectants.cfm
http://www.pulseinstruments.net/freechlorineandorp.aspx
http://hannainst.com/hannasanitationsystems/http://anrcatalog.ucdavis.edu/pdf/8149.pdf
https://www.clorox.com/dr-laundry/expiration-date/
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Whats the best sterilizing agent for a hydroponics reservoir?
There are many ways to have a sterile reservoir, chlorine, H2O2, Ozone, etc. All have pros and cons. I'm going to focus on Chlorine because its easy to measure, cheap and effective.
I have root rot/ pathogen problem how much extra chlorine should I add?
Chlorine is best used to prevent pathogen outbreaks not to treat them.
Is running a sterile res better than using beneficial bacteria?
I'm no aficionado on bennies, so I couldn't say. However some claim that they tried running sterile and it didn't work for them; bennies being the only thing that works. I doubt they were properly using a sterile reservoir in the first place but who knows.
If I don't have a sterile reservoir or use beneficial bacteria will I get a root rot/pathogen problem?
Not necessarily. Many people claim to use neither and have great results. If you focus on using plenty of dissolved oxygen, keep nutrient solution at a reasonable temperature, use a relatively low EC, do solution change outs at reasonable intervals, keep organic material, nutrients and additives out of nutrient solution, and keep away light leaks.......you should be fine too.
However, I do always recommend using bleach as a sterilizing agent in between grows.
I heard chlorine is bad for plants?
Not necessarily. Most plants can tolerate up to 5 ppm of chlorine.
This is great, I found an old gallon of bleach underneath my kitchen sink. This should be enough to sterilize my reservoir for years right?
If your going to use bleach, its better to use newer bleach. After a year the composition has drastically changed.
My tap water has chloramine, its the same as chlorine except it doesn't dissipate as fast right?
Not really. Chloramine is not as effective as oxidizing as chlorine.
I heard all I need to do is add 1ppm chlorine per gallon every 2 days to my reservoir and I'm set.
Not really. FYI most municipal tap water that is disinfected with chlorine has .5 to 1ppm of chlorine. The EPA allows for up to 4ppm. This doesn't mean its going to be ideal for your hydroponic system. Read below.
Jiji, how did you become an expert on sterile hydroponics?
I'm not, and don't claim to be. Most of this info is just ripped off the net, I'll try to cite my sources. I'm just trying to gather facts and disseminate information to the hydro community.
How a sterile res works with chlorine as an oxidizer
---------------------------------------------------------------------------------------------------------------------------------------------
Microbes are surrounded by a cell membrane surrounded by structural proteins. These proteins maintain their shape. When a strong oxidizer is present such as chlorine, proteins are released and they are accepted by the oxidizer. When the cell loses its proteins it loses its structure and disintegrates.
The higher the ORP (oxidization Reduction Potential) the faster proteins are lost from cells.
When you add chlorine in the water, thats called the Total Chlorine. Some of the Chlorine will bind with dirt, debris, plant etc., this is called Combined Chlorine. Combined chlorine is chlorine that is lost for disinfection. The rest is called FREE CHLORINE. Free Chlorine is in two forms, HOCL (Hypochlourus acid) and -OCL (Hypochlorite ion). HOCL is the only form that is active for oxidation. HOCL and -OCL change in proportion dependant on PH. Free Chlorine is about 95% HOCL at a PH of 6.5 and almost a 100% at PH 6.0. HOCL can generally easily be measured using a redox/orp meter.
To know the disinfection properties, you need to know the ORP. ORP is measured in mV. Different oxidizers have different strengths. For chlorine a general accepted ORP value in hydroponics is 600mV to 750mV. This can vary on biological load, but probably closer to 600mV is better as achieving 750mV or above requires a fair amount of chlorine.
I use calcium hypochlorite, in the form of pool shock. Its extremely cheap and easy to find. I make a liquid batch so that 1 ml when added to a gallon of water will equal 1 ppm chlorine. Dose as necessary usually every two days.
Further reading and sources:
---------------------------------------------------------------------------------------------------------------------------------------------
http://www.hannainst.com/literature/Sanitation - UConn results.pdf
http://www.hannainst.com/literature/lithydro_sani_sys.pdf
http://water.epa.gov/drink/contaminants/basicinformation/disinfectants.cfm
http://www.pulseinstruments.net/freechlorineandorp.aspx
https://www.clorox.com/dr-laundry/expiration-date/
