Using UV light + H2o2 to sterialize rainwater for hydroponics ?

[drgr33nuk]

Hey guys,

Just wanted to run this past some people in the know. I plan to make a sort of "rain water processing unit" what consists of a UV sterilizing bulb & carbon filter. I've been reading about using H2O2 to boost the sterilizing by creating hydroxyl radicals (·OH).

Now I'm no chemist but after reading a few head spinning documents it looks like the flow rate, amount of UV & H2O2 is key to making this work.

I'm sure I have the flow and UV right but how the fcuk do you work out how much H2O2 to put in ? I'll type what I THINK is right here and let someone correct me if they would be so kind.

I'm using GT Liquid Oxygen and it has a specific gravity of 1.20 @ 20 degrees celsius. Now by the looks of it (I won't go into details) but the magic number to make this work is around 5 - 10 mg/l of water. So assuming 1ml of LO weighs about 1g it would take around 5 - 10 ml per litre of rain water ?

Seems alot ?

 

[drgr33nuk]

1ml lo = 1.2g sorry so 7 - 12ml per litre ?

 

[drgr33nuk]

Sorry my maths was wrong apparently to get a concentration of 10mg/l of H2O2 @ 17.5% will be just off 1ml per litre

 

[Only Ornamental]

I imagine if your smoking skills would be similar to your math skills, your 420 should look like this (sorry dude, no offense) .

A solution of hydrogen peroxide (usually in water) at 1.2 g/ml is roughly at 40%. So if you mix 1 ml with 1 liter of water, you'd have approximately 400 mg per liter. In case it is 17.5% as you stated (don't know from where you have that intel) you'd end up with ~175 mg (neglecting density) instead. Hence, you'd need about 0.03 to 0.06 ml in 1 liter water to obtain 5-10 mg per liter (BTW that'll be 5-10 ppm).
That's not much but hydroxyl radicals are extremely potent and taking too much would damage your plants. That way, they react before encountering the roots and everything is fine.

Good luck, you seem to need it

 

[Granger2]

I won't wade into the math here, but If you have proper UV set up, that will sterilize it.

There is considerable margin for error because the H2O2 will degrade into water and O2 pretty quickly. I can't tell you how long that takes. One afternoon, I filled a 5 gal bucket with tap out of the hose for dog water. I put 5 TBL of 3% peroxide in it and stirred. One of my dogs took one lap and wouldn't drink more. Next mid morning the bucket was lined with bubbles, and he drank freely. During hot temps. So if you go overboard with the peroxide, you can give it 24-36 hours and there should be no problem with plants or microherd. Good luck, and keep us apprised on your experiences. -granger

 

[drgr33nuk]

thankyou for replying and setting the record straight ! That figure came from a well known wholeseller of products in the uk :/ nvm

hydroxyl radicals have a short life and there is plenty of matter for them to break down so I think I should be ok. This is for a recirculating holding tank. I bought a carbon / uv filter and noticed they sold "uv booster". After a bit more research it turned out to be H2O2. So I dug a bit further and got blinded by science. I don't understand how to convert 10mg/l to ml. 17.5% came from the side of the bottle. Saftey data sheet reads 17.5% h2o2 82.5% h2o.

just thought because i already have the holding tank + adding h2o2 to create two oh would be better as its catalyses the reaction of h2o2 and improves its potency. And oxy plus is cheap

I'll post some pics tomorrow of the setup and the difference in clarity of the water but to tell you the truth i suppose it will be hard to tell if OH H2O2 or UV done the cleaning without testing for the presence of hydroxyl radicals.

 

[drgr33nuk]

thought I'd add this little bit to explain what im trying to achieve and explain the principle.

by exposing H2O2 to light with a wavelength less than 365nm (UV). The H2O2 molecules are activated to form 2x .OH (Hydroxyl radical).

Hydroxyl radicals react very fast <1 sec with other H2O2 molecules and other molecules / compounds present in the water.

Again if I'm wrong correct me but getting the correct dose of oxy plus is crucial because too much and H2O2 will scavenge the OH and not enough will probably end up with most of the H2O2 reacting with organic matter in the water and hardly any hydroxyl radical will be produced ?

 

[drgr33nuk]

Sorry to keep replying but you cannot edit posts. Here are some pictures of the system in use.

Going to get some methylene blue dye to see if it's working and I'll let you know.