How to operate a sterile hydroponic system

ShirkGoldbrick said:

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/

Click to expand...

BuddyLeeCU said:

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.

Click to expand...

BuddyLeeCU said:

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.

Click to expand...

jijiandfarmgang said:

FAQ
---------------------------------------------------------------------------------------------------------------------------------------------

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

http://hannainst.com/hannasanitationsystems/http://anrcatalog.ucdavis.edu/pdf/8149.pdf
https://www.clorox.com/dr-laundry/expiration-date/

Click to expand...

squirt1961 said:

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

Click to expand...

jijiandfarmgang said:

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

Click to expand...

completenoobie said:

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

Click to expand...

completenoobie said:

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.

Click to expand...

Aeroknow said:

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.

Click to expand...

completenoobie said:

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

Click to expand...