How to operate a sterile hydroponic system

[d0rk2dafullest]

VERY GOOD INFORMATION. i have read people also use 10% germicidal bleach solution into the res as well with no ill effects.

 

[Banana444]

@jijiandfarmgang
Would this work for any hydroponics system? I am giving dwc a shot and will eventually make a small rdwc system. I already have some GH micro and bloom and would like to make this as simple as possible so those would be the only nutes+calmag. I have a bluelab guardian otw for monitoring.

 

[jijiandfarmgang]

Yes it will work in any hydroponic system. I tried to make the description on orp and sterile complete. Its actually not all that easy to get it right and you have to stay on top of everything.

Pre-bought bennies probably be easier.

- Jiji

 

[BuddyLeeCU]

Switching to ebb and flow cut all my issues. No more clogged sprayers and pumps no more root rot issues etc etc. I'm not running bennies or sterile. I'll put up a post later this week with the ebb and flow design. I did switch to JR Peters nutes with Epsom salt and MOST mix. Super easy to mix up, I keep a concentrate and just dilute it 1 to 10.

Banana- I would strongly recommend against dwc. Very resource intensive and the environment way too prone to problems.

 

[ShirkGoldbrick]

Great post!

Except, UV light will not precipitate minerals unless it produces ozone. Chlorine and various other oxidizers do have the potential to oxidize (and thereby precipitate) minerals.

Also, you need to manage ORP, or total/free chlorine. There is no "dose per x gallons" that will work for everyone. If you would like a deeper understanding on the subject just check out my thread:
https://www.rollitup.org/t/pathogen-control.861821/

 

[BuddyLeeCU]

Great post!

Except, UV light will not precipitate minerals unless it produces ozone. Chlorine and various other oxidizers do have the potential to oxidize (and thereby precipitate) minerals.

Also, you need to manage ORP, or total/free chlorine. There is no "dose per x gallons" that will work for everyone. If you would like a deeper understanding on the subject just check out my thread:
https://www.rollitup.org/t/pathogen-control.861821/

Your issues are almost certainly a matter of water temp. I focused on controlli g temp, light, and the Jr peters no nonsese mineral salts. I don't add Benes and I dont run sterile. I'm not even using RO water and everything is superb. I'm Usk g the 2 week rotation on 4 ress's all different concentrates for different cycles. Every 4 weeks I rinse and clean each ress

For the system I bought sterilite tubs and 4x4 vinyl fence posts. The tubs are my flood tables. The fence posts are 18" each and have 5 each 2" net pots on the top. Holes on the bottom and sides and filled with hydroton. I transant bare root when clones have 3" roots. The fence posts rotate through the tubs as the plants grow.

 

[ShirkGoldbrick]

Your issues are almost certainly a matter of water temp. I focused on controlli g temp, light, and the Jr peters no nonsese mineral salts. I don't add Benes and I dont run sterile. I'm not even using RO water and everything is superb. I'm Usk g the 2 week rotation on 4 ress's all different concentrates for different cycles. Every 4 weeks I rinse and clean each ress

For the system I bought sterilite tubs and 4x4 vinyl fence posts. The tubs are my flood tables. The fence posts are 18" each and have 5 each 2" net pots on the top. Holes on the bottom and sides and filled with hydroton. I transant bare root when clones have 3" roots. The fence posts rotate through the tubs as the plants grow.

Buddy, yes, I believe part of my problem was water temps. Pathogens can grow much more quickly under higher temperatures.

You're very lucky to not have any issues, and I hope that you continue to not have any issues. Perhaps beneficial bacteria have colonized your system without any effort on your part.

The thing is, it doesn't take much for the whole thing to hit the fan. One bad bacteria could be introduced somehow into your grow room and it might feed off of/thrive in conditions that other bacteria don't or cant. If this does happen then you either have to try introducing more beneficial bacteria to the point some may just thrive in the same conditions and feed off of the same as the pathogen or you'll have to go sterile.

Again, I'm glad everything is working for you now, but if sometime in the future it hits the fan and you want to go sterile then you could try cleaning everything and running it like jiji recommends - the chlorine you add may yet just be enough. If it isn't, then you're looking at a free chlorine controller or an ORP controller and possibly UV light.

Another note: I also have been setting up a high pressure aero system. I was running initially off of 12V pumps but they were rated at the minimum threshold for the misters. The "slime" still colonized my RO water in the res to some degree, but I was able to root with it. I kept clogging sprayers at the lower pressures and tried to put in a 5 micron filter, but the pressure drop was too much to maintain spray. I have since bumped up pressure and added the filter.

Moral of the story is, my room is 80, the res (due to constant evaporative cooling of the water in the table) was probably ~60 (didn't monitor) and I still got it. Perhaps the misters killed it and so it didn't get on the roots - but before I get this thing fully running I will be running sterile.

PS: I would be willing to send you a few gallons of my contaminated water if you want to try running it through to prove it doesn't colonize your system.

 

[Banana444]

Switching to ebb and flow cut all my issues. No more clogged sprayers and pumps no more root rot issues etc etc. I'm not running bennies or sterile. I'll put up a post later this week with the ebb and flow design. I did switch to JR Peters nutes with Epsom salt and MOST mix. Super easy to mix up, I keep a concentrate and just dilute it 1 to 10.

Banana- I would strongly recommend against dwc. Very resource intensive and the environment way too prone to problems.

Thanks, but I am loving dwc. No problems whatsoever. I am using hydroguard and dont even change my res now that the plant is drinking half gallon of water a day. All I need now is to make an rdwc.

 

[squirt1961]

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/

Thank you very informative post. I've been using beneficial bacteria called great white 1/4 tsp per gal in my hydro setup. Thinking about switching to tap water instead of distilled. Wondering if this will cause problems with the good bacteria

 

[jijiandfarmgang]

Thank you very informative post. I've been using beneficial bacteria called great white 1/4 tsp per gal in my hydro setup. Thinking about switching to tap water instead of distilled. Wondering if this will cause problems with the good bacteria

If your going to use tap water with bennies find out whats in it. Get a water report from your municipality. Then go from there.

But no, don't mix city water and great white.

- Jiji

 

[squirt1961]

If your going to use tap water with bennies find out whats in it. Get a water report from your municipality. Then go from there.

But no, don't mix city water and great white.

- Jiji

Thank you I'll make sure not to use one or the other together

 

[Gregor Eisenhorn]

Absolutely outstanding thread, very informative and helpful.

I'll order some calcium hypochlorite for my reservoir. It's symbol is if anyone is wondering, should help finding the stuff in other countries.

Actually I was wondering if pure Ca(CIO)2 has the same strength as the pool shock one (which is about 49%)? Could anyone help me with this?

 

[completenoobie]

ok, who can help with some math on this issue??? I had someone give me a formula that would give me 5ppm, 0.5g per 10 gallons.

I want to make a concentrate so I can add 1 oz, 30 mL, a shot glass of concentrate to 3 gals and end up with the same 5 ppm.

I can't remember how I did it and didn't write anything down but I came up with about 2.5g in a gal jug of water for the concentrate and that would give me approx 5ppm when 1oz of that was added to 3 gallons of water.

Can anyone help me with this math? I'm gonna go back and look at the post with the math in it again (AGAIN) and see if I can't work something up, but conversions fuck me up

Thanks for this thread, suddenly I need it after years of no problems at all.

 

[completenoobie]

trying to work through it I actually think I missed something originally and came up with a formula to make 5ppm at 1oz/gal instead of 1oz/3gal

I do have to say. reading through this thread, every single time I saw the letter g used for gallon I read and thought gram instead and just can't get over it.

5mg/L = 5mg(x3.785l/gal)/gal =18.925mg/gal


X3gal = 56.775mg/xxx (quantity of concentrate which happens to be a gallon at 128 oz per)


X128 = 7.267g???

On my original math I think I forgot the x3 step and made it to work out to one ounce per gallon would give 5ppm, at approx 2.442g in a gal of water for the concentrate, then add 1oz per gal final which I meant to add 1 oz per 3 gal final.

although it may work better because 2.4g is not dissolving that well in a single gallon, so I may not be able to get 7.3g to dissolve entirely. time to check the merck and see what the solution rate is.

Now, do I have to take into account the percent and divide that 7.3 by .49 ??? which makes it even more unlikely to achieve my original goal of being able to add 1oz of concentrate to 3 gal water to come up with 5ppm

 

[Aeroknow]

trying to work through it I actually think I missed something originally and came up with a formula to make 5ppm at 1oz/gal instead of 1oz/3gal

I do have to say. reading through this thread, every single time I saw the letter g used for gallon I read and thought gram instead and just can't get over it.

5mg/L = 5mg(x3.785l/gal)/gal =18.925mg/gal


X3gal = 56.775mg/xxx (quantity of concentrate which happens to be a gallon at 128 oz per)


X128 = 7.267g???

On my original math I think I forgot the x3 step and made it to work out to one ounce per gallon would give 5ppm, at approx 2.442g in a gal of water for the concentrate, then add 1oz per gal final which I meant to add 1 oz per 3 gal final.

although it may work better because 2.4g is not dissolving that well in a single gallon, so I may not be able to get 7.3g to dissolve entirely. time to check the merck and see what the solution rate is.

Now, do I have to take into account the percent and divide that 7.3 by .49 ??? which makes it even more unlikely to achieve my original goal of being able to add 1oz of concentrate to 3 gal water to come up with 5ppm

Not sure what exact ppm this gives me, around 3? but for my cloner:
1gram of the Calcium hypochlorite to 1gal of water to make my stock solution.
I add 30ml/5gal of that stock solution into the cloner.

 

[completenoobie]

have you been doing that for some time and with no ill effects?

according to the math on the first page of the thread, it sounds like yours would be way over 3 ppm. I can do math, I can't do conversions and formulas. Or maybe I'm looking at it wrong.

Either way I need help figuring it out.

Actually now that I look at it, it seems like your concentrate would provide far less than 3ppm

Shit, I am confused.

 

[Aeroknow]

have you been doing that for some time and with no ill effects?

according to the math on the first page of the thread, it sounds like yours would be way over 3 ppm. I can do math, I can't do conversions and formulas. Or maybe I'm looking at it wrong.

Either way I need help figuring it out.

Actually now that I look at it, it seems like your concentrate would provide far less than 3ppm

Shit, I am confused.

Yeah, like I had said, not sure exactly how many ppm's it is.
I have been adding this much every 3 days for as long as I've been using a cloner. Zero slime this way.

 

[completenoobie]

Yeah, like I had said, not sure exactly how many ppm's it is.
I have been adding this much every 3 days for as long as I've been using a cloner. Zero slime this way.

Cloner? Rooting cuttings and this amount has no ill effects? Clones root easily, quickly, and w/o high fail rate?

 

[Aeroknow]

Cloner? Rooting cuttings and this amount has no ill effects? Clones root easily, quickly, and w/o high fail rate?

I wouldn't be recommending that dosage if it had ill effects and a high fail rate

 

[biostudent]

If your reservoir is non-flammable, non-corrosive, can just pour some ethanol and light it on fire. That's how most instruments are sterilized in the lab. But my reservoirs are all some plastic, PE, PVC or rubber, and I use 35-42% H2O2. Kills most irritant microbes; algae growth has been the only real problem in my setups and H2O2 devours it. Plus, the decomposition of H2O2 releases oxygen in to the water.

H2O2 doesn't offer full sterility though. Any catalase-positive microbe is able to metabolize H2O2. Staphy's, salmonella, e.coli, enterics will survive.
https://en.m.wikipedia.org/wiki/Catalase#Bacterial_identification_.28catalase_test.29