Yes but your water will be coming around again quite quickly, the water in a pond would take alot longer to go around

Does anyone know the continuous exposure time required to kill microbes and algae found in a W/C system?

No clue, but your best bet would be to respect the max flowrate ratings.
Power / max gph / Max tank size (g)
4 W / 120 / 75
8 W / 180 / 150
15 W / 450 / 300
30 W / 750 / 500

This is going to depend on your setup.

I dunno, i bet tank size has a ton to do with it.
These are what, 1/2" ID?
Do the flow calcs and figure out exposure time.
But considering that each of those has said exposure occuring slightly more often than once per hour (flowrate is some higher than tank size) and we are tlaking a watercooling system with less than 1 gallow total (most systems out there), then for even the 4W system, we are talkiing about 75 times the overall exposure time for each "bit" of water. Thats gotta mean something in terms of sterilization.

I have done the flow calcs and show about .2 ft/s through the light. (Do I need to prove this?? :shrug: ) I need a recommended lethal exposure time of the pests to gauge the effectiveness of this light. I just want to know how many times the spores, or whatever, will need to pass through.

so - i am talking 2.4 inch/sec. and mabye 2s exposure time per pass with the short 4W unit. (Mabye 5" useful length)

This was figured at 150 GPH (or 2.5 GPH), 30 Deg. C Water.
I can reach this flow number as I might plumb the light as a kidney loop or use it in a machine tool:D

Actual flow through my system is much slower and I can easily adjust for that -should I figure out how to get this in my case and into my primary loop. Thus the (exposure time) / pass will be even higher.

I am looking for the magic figures on UV lethality vs. Algae & Bacteria. -Then I am going to need to figure average intensity...

I am guessing the light has mabye 3.5 to 4 in^2 area of water column.

Aha!
Found some stuff:
From here:
http://www.photobiology.com/photobio...in/image15.gif
where "A" refernces lethality for 270nm light

This source appears to be quite fantastic, offering up this jewel:
and an accompanying chart, where k is listed for many differnet pathogens.

NONE of the "k" (rate constant) values go above .002503 in WATER (from listed bacteria/virii, etc).

Now, i'm too lazy to do the actual math (i just got my BS in mathematics, after all) but with the power output of the light, one can easily calculate survivability per GPH (flow).

The question then arises, how much survivability do we need? because the water is recycled through this system, does that mean we can assume that each cycle is a new "kill off"? Or that only the resistant bacteria remain?

I guess we will be answered once someone computes the lethality for the flow rates they describe. (by "they", i mean the producers of these sterilizing devices)

Althornin -This is some great stuff! -You even hit our target wavelength. Thank you for the great research -and lightning fast too.

I will gladly attempt the figures for various flow rates and corresponding exposure times. However this will have to wait a few days b/c I have to go earn my pay in another state. If I am not beaten to it...

Does anyone have figures for algae resistance to UV?

Are there any other nasties we are ignoring?

And we need to answer Al's question "how much do we need" This might fall into place with the new data on lethality, but will definately be a topic for discussion.

Here is a really good link for this topic. It gives the germicidal light energy required to kill common microorganisms.

http://www.debary.de/eng/pdf/aquagb02.pdf

I have also saved this file in case it gets lost...

Quotes from this source:

according to my readings on the subject:
has been answered.
Each cycle is a new kill off.


Ok, i had a huge math post typed up, but i figured, SCREW THAT - So i made some sweeeeeet ass excel file to do all the math for us.

Please look over my maths and look for any errors.
If you have any questions about what i am doing, ASK! I make mistakes, so i'd like to know what you guys think.

Anyways, let my give the results here:
For a system, using the 4 watt unit, with flow rates of 10 liters/minute, one liter total system volume, assuming 30% efficiency as per CoolRods recent post, we get:

% kill Off per Hour:
66.47220214

%kill Off per Day:
100

Now, given the max the Sterilizer is rated for, being 120 GPH and tank of 75 gallons, we get: 7.6 l/min and a 284 liter tank, we get:

% kill Off per Hour:
0.384047722

%kill Off per Day:
8.821302748

Now, this doesnt look so hot, eh?
Yet, manufacturer says this amount will be enough to "clarify" the water - those max values were not for sterilization, but for "Clarification".


Ah yes, these results also assume no growth during said time, so the real figures will be less. hwoever, as long as kill off is greater than growth, we win....
And, play with the file - tank size is a HUGE contributor to changes in kill off.

The EXCEL file:
UV Kill Off

AL -Great Work!...and sorry for the late response...

I immediately started using your spreadsheet to juggle numbers. With my new Johnson pump from bigben2k's thread -I should be able to hit 10 L / min with my setup, though I really can't see why flow rate would affect the UV system...It seems like all we need to know is volume and watts.

If we assume that all of the water will go through the clarifier sooner or later, then can't we spread our volume into a thin sheet and divide the effective watts over this area?

NOTE: This is exactly how Althornin's spreadsheet behaves -play with it!

Al. -don't hesitate to post math here, especially if you already had it typed up...I know that I always enjoy an education...

Also, it would be my bet that a slow flow rate will result in greater efficiency of the UV light kills -much like small doses of penicillin vs. heavier -more complete- doses. Then there is the question of developed tolerance...

The Tetratec UV5 Clarifier is a 5-Watt unit that is fairly compact (scaling from the hose barbs) and touts 300 gph flow rates. It comes with universal-cut-to-fit, 1/2", or 3/4" hose barbs -depending on whose ad you read...or apparently depends on who you buy the unit from...

The "Tetratec UV5 Clarifier" looked promising as a Reservoir / Air Trap -but the inlet would probably be too high for this purpose.

Replacement bulbs are cheaper for the Angstrom 2537 Sterilizers than the Tetratec UV5 Clarifier and bulb life is reduced by frequent start / stops. I think we will only have to use these weekly, or possibly less often. And for the really High Flow people -you could plumb this as a "kidney loop" by only bypassing part of your water through it.

Here is a thought: Why not sterilize the water / components before putting a system together? Obviously this is not real practical.

Also, if we use distilled water -Where are these microorganisms coming from? Airborne?

Also, if we use distilled water -Where are these microorganisms coming from? Airborne?


I think there coming from the deep dark places in our WC setups...the rad.


H

Well, flow rate affects the time spent in each "round" in the UV light. Try it out, the "S" that is calculated is the survivability of each "round" - i find that for typical flowrates in WC systems, it doesnt vary the survivability much at all.
The only really shady part of my math is that Intensity is measure in mJ/cm^2 - yet we are dealing with the light shining on a VOLUME of water, so i simply used the surface area of that volume. This could be off by a fair margin.

The blue highlighted values are user inputable, where most of the are physical things based on the UV sterilizer you are looking at using and the others are absed on your WC system. Oh and one value is "k", the rate constant, which is different for each pathogen. I pulled one from a source i quoted above -
here

If i examine my spreadsheet, i find that even Airspirit will be satisfied with one fo these, as resevoir size plays a large role also...this is to reference his comment in the previous thread that i dont know how much flow he has :) Doesnt matter man - you dont have a 300 liter resevoir either. All he needs is one big enough in diameter for his main line.

from the rad, from touching the barbs, etc. Did you mouth siphon to start with? etc...
Sterilization isnt really nessesary.

Even Airspirit could route some of his water through the UV clarifier...Mabye put it inline with a chipset cooler or something...

In Althornin's spreadsheet:

for "% Kill-off Per Day" we have the formula:
=(1-A2^(K5*60*24/I9))*100

If 24 is the number of hours in a day -->and I change it to a 5
--> =(1-A2^(K5*60*5/I9))*100

I still get a result of 99.5763325 effective sterilization in 5 hours.

Al. -Is this correct?

Now I have no idea how often to run this thing. I would definately run it for the first 48 hours, though. And then, what, weekly for a few hours?

I don't want to have to run it unnecessarily...a few extra BTUs, bulb life, etc.

The formula for kill offper day is simply
surviveability^(flow rate in Liters per min * mins per hour * hours per day / system volume in liters)

this however, gives an overall surviveability, so we subtract it from 1 to get kill off, and times 100 to get percent.

now, the interesting part is in the s^(blah blah) part:
look at units:
liters*mins*hours/mins*hours*days*liters
it gives cycles through system per day...
The thing is, with a 10liter per minute flow rate and maybe a liter of volume, you pass each bit of water through the UV light 600 times per hour :)
So if only 1% dies each hour, thats .99^600, which is .0024, and so per hour, almost everything is killed off.
you have to realize, these things are DESIGNED to deal with a good flow rate (but not even 10 liters/min - 7.6 for the 4 watt device) but HUGE tank volume, meaning water only sees the inside of the device like two times per hour! So in our case, we are running water through it 300 times more often than it needs....
en these maxed systems, each bit of water runs through less than twice per hour! so yes, even 5 hours on could easily kill damn near everything... its the same effect as running those things in a tank at max spec for like 1500 hours :)

ah yes, slightly updated excel file, all i added was common unit conversion spaces (gallons to liters and inches to cm) just for ease of use. hopefully its more than just you and me reading this stuff, CoolRod.

I'm loving every minute of it.

Thanks for all your hard work, I've already got plans for a Tetra UV5.

I'm just wondering how bad things like Water Wetter or Anti-Freeze will put a film on the blub..

H

h4rm0nix -If you are looking into these things then you know that the bulb is usually inside of a quartz tube...and some of these units are offered with integral wipers. You pull a handle located at the end of the unit and it pulls wipers along the quartz tube and inside of the housing. Thus allowing water to flush out the scum -in an aquarium application. Sooo if you are concerned with this you might want to look into this type of unit.

Althornin, I hope they are too. We have put a lot of time and thought into this and I think we have something that will be effective.

I am ordering a "Tetratec UV5 Clarifier" today. It offers a 5-Watt bulb vs. the 4-Watt we have studied, and the geometry is similar. I am going to apply your figures to my system WRT volume, flow, watts, etc. -and create a theoretical gauge of the system's effectiveness. But only time will tell if the thing helps or not...

I found some more interesting data from this source:
http://www.aquaultraviolet.com/pondbasics.html#7

As bigben2k said earlier -these lamps contain mercury:
Uh-Oh:
Let's hope that copper will not diffuse into the water too rapidly...any materials people out there?

There's something about an electrical solution that I just like. ;)

But at ~$100, it's out of my price range, where a few dollars of chemicals would do.

So is there any way that we could build a unit ourselves?

The parameters should be as follows:
-it must be encased, to where the UV-C light can't get out. if it means using a 3/4" elbow at each end, that's fine.

-it should have a very low flow restriction.

-it could run on DC or AC.

-A 4 Watt source is apparently more than plenty.

Obviously the lightbulb would sit outside of a clear tube: would acrylic or glass be OK? I'm envisioning a build similar to my airtrap.

very interesting thread

i dont know if your tyalking about a different kind of uv clarafier(sp) but all the ones i have read about dont actually kill the algae they force it to clump together so it can be filtered out by a seperate filter

http://www.tlc-direct.co.uk/Main_Ind...s_1/index.html

this might mean you need a filter in your system too

Idris

That is absolutely true, according to my readings, the UV neuters the microorganisms. It does not kill them. Sooo...if you have a lot of build-up and you install a UV clarifier -->you will need a filter to catch the contaminants. The filter would have worked anyway, but there would be a rapidly growing colony of nasties in the filter!

BTW Moriquendi's above link points to the least inexpensive UV clarifier that I have seen.
The best price that I have seen for the Angstrum unit is $69.00.

Moriquendi's "Vorton 4500 Ultra Violet Clarifier" is selling for $38.50. Wow.

bigben2k -I doubt that you can buy a bulb and ballast that cheap!

Thanks Moriquendi and welcome to ProForums.

Whoa.

So we need a filter as well?

This could add to the pain. I was hoping once I've got a cleaned system up and running the clarifier would prevent new growth..

Am I not understanding the process?


H

Ahh, Thanks for the link, missed it before.. So neutering it is then.


Time for some redesign..

H