Fishy Business

UV flow rate

Kensington Reefer

Kensington Reefer

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Thoughts, comments

I’ve got 2 57w AquaUV’s
300DT, 40Fuge, 50g in sump
My main purpose is as a bug cyst (ich) zapper
Do I run just 1
Do I run both...parallel or in series
At what flow rate
 
If you were running two, I would think in parallel is better. 600gph running through two in parallel is 300gph each. Less gph means longer dwell time. Longer dwell time means kill more stuff.

If something gets through the first UV at 600gph why would it get killed by the second one?
 
richiev said:
If you were running two, I would think in parallel is better. 600gph running through two in parallel is 300gph each. Less gph means longer dwell time. Longer dwell time means kill more stuff.

If something gets through the first UV at 600gph why would it get killed by the second one?
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I think for turnover rate of water. Unless you planned the plumbing in different input and outputs, there would be some amount using already UV sterilized water if running in parallel. It could be minimal and not be a factor. Plus in parallel would complicate things in terms of plumbing or an additional pump.

600 gph in series should theoretically be close to 300gph in terms of dwell time.
 
richiev said:
If you were running two, I would think in parallel is better. 600gph running through two in parallel is 300gph each. Less gph means longer dwell time. Longer dwell time means kill more stuff.

If something gets through the first UV at 600gph why would it get killed by the second one?
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It’s UV exposure- intensity level (watts) x seconds exposed (inverse of gph). So having them in series means twice the exposure, the equivalent of running half the flow rate (like Randy said). That said, having them in parallel is probably just about as good since on average you’ll be delivering the same increased intensity x exposure to whatever is in the water.

Killing stuff in this case isn’t black and white, it’s probability of killing really. Even the term killing isn’t really what we’re going for, more like enough DNA damage that it can’t replicate. There’s a lot of randomness involved making it more statistical, so really it just boils down to more is better, up to the point of practicality.

Some people who have 2 UV’s plumb them separately, one high flow for algae and bacteria, and the other low flow for parasites. Theoretically it makes sense, but again this isn’t as exact of a science as people want it to be.
 
JVU said:
It’s UV exposure- intensity level (watts) x seconds exposed (inverse of gph). So having them in series means twice the exposure, the equivalent of running half the flow rate (like Randy said). That said, having them in parallel is probably just about as good since on average you’ll be delivering the same increased intensity x exposure to whatever is in the water.

Killing stuff in this case isn’t black and white, it’s probability of killing really. Even the term killing isn’t really what we’re going for, more like enough DNA damage that it can’t replicate. There’s a lot of randomness involved making it more statistical, so really it just boils down to more is better, up to the point of practicality.

Some people who have 2 UV’s plumb them separately, one high flow for algae and bacteria, and the other low flow for parasites. Theoretically it makes sense, but again this isn’t as exact of a science as people want it to be.
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I'm not completely sure that makes sense to me. There's likely some exposure curve to this, but if going slower doesn't matter that much, then generally there'd seem to be no reason to slow down flow either.

Eg taken to the extreme, you might as well run full speed through the UV at max flow rates, because you will turn the water over faster.

100gph on a 100gallon tank in theory being every bit of water gets exposed once an hour. 200gph, each exposure is half as long, but you have twice as many exposures, so the same amount of total exposure.

Serial at 600gph then also being the same as parallel at 300gph, because each unit of water would get the same amount of total exposure.
 
richiev said:
I'm not completely sure that makes sense to me. There's likely some exposure curve to this, but if going slower doesn't matter that much, then generally there'd seem to be no reason to slow down flow either.

Eg taken to the extreme, you might as well run full speed through the UV at max flow rates, because you will turn the water over faster.

100gph on a 100gallon tank in theory being every bit of water gets exposed once an hour. 200gph, each exposure is half as long, but you have twice as many exposures, so the same amount of total exposure.

Serial at 600gph then also being the same as parallel at 300gph, because each unit of water would get the same amount of total exposure.
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Not the same at all. Running in serial essentially makes the two UV units one UV unit with near constant exposure to UV through both UV units.

Cycling water through one UV and then through the entire tank in hopes it will go through the UV again is not the same and would not count toward dwell time.
 
RandyC said:
Not the same at all. Running in serial essentially makes the two UV units one UV unit with near constant exposure to UV through both UV units.

Cycling water through one UV and then through the entire tank in hopes it will go through the UV again is not the same and would not count toward dwell time.
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The 2 UV in series...
There is a “gap” between the 2 units via the connection plumbing (as short as possible)
 
RandyC said:
Not the same at all. Running in serial essentially makes the two UV units one UV unit with near constant exposure to UV through both UV units.

Cycling water through one UV and then through the entire tank in hopes it will go through the UV again is not the same and would not count toward dwell time.
Click to expand...
If you pump water though two in series at 600gph, that's the same amount of dwell time as water going through two in parallel at 300gph.

There's two roads that are 30 miles long running parallel to each other. The speed limit is 30mph. I send a car down each road. The cars will dwell on the roads for 1 hour.

There's a road that is 60miles long, which is made up of two 30 mile long segments. I send a car down it at 60mph. The car will dwell on that road for 1 hour.

Turns out all those cars are convertibles with the tops down. Bald old men are driving, with their partners sunbathing in the back seat. Everyone comes out with an increase in melanomas.
 
Doesn’t UV exposure only kill ich while in the swimming stage?
Id definitely plumb one upstairs Dt to DT to capture free swimmers down low or around the level most of the fish swim with low flow 200-300 gph for the longest exposure making it count. Uv in the sump your only treating the small percentage of swimmers that make it down their and thats not 100% nor is in the DT logistically..Definitely higher percentage of swimmers up top in DT that never make it down the overflow especially in large deep sand bed tanks like yours!! In all the Uv is managing ich not 100% radication as what most articles point out..Two up top at different ends of the tank and levels just ups the percentage where the fish are swimming.. Depending how serious of an outbreak may depend on placements..I do run Uv alot slower then recommend maybe to slow and always feed mixed frozens and heavy on the garlic pellets thankfully never had an ick breakout yet knock knock!!!
Good luck!!
 
richiev said:
If you pump water though two in series at 600gph, that's the same amount of dwell time as water going through two in parallel at 300gph.

There's two roads that are 30 miles long running parallel to each other. The speed limit is 30mph. I send a car down each road. The cars will dwell on the roads for 1 hour.

There's a road that is 60miles long, which is made up of two 30 mile long segments. I send a car down it at 60mph. The car will dwell on that road for 1 hour.

Turns out all those cars are convertibles with the tops down. Bald old men are driving, with their partners sunbathing in the back seat. Everyone comes out with an increase in melanomas.
Click to expand...
Won't two Uv in different locations or parallel with two intakes have a better chance netting more swimmers then two plumbed inline with one intake? My Uv is plumbed after my return pump plus a second Uv stand alone down deep in the DT run as needed. I really don't mind a pump down low on the back wall others might though..
 
richiev said:
I'm not completely sure that makes sense to me. There's likely some exposure curve to this, but if going slower doesn't matter that much, then generally there'd seem to be no reason to slow down flow either.

Eg taken to the extreme, you might as well run full speed through the UV at max flow rates, because you will turn the water over faster.

100gph on a 100gallon tank in theory being every bit of water gets exposed once an hour. 200gph, each exposure is half as long, but you have twice as many exposures, so the same amount of total exposure.

Serial at 600gph then also being the same as parallel at 300gph, because each unit of water would get the same amount of total exposure.
Click to expand...
Taking anything to the logical extreme will make it seem ridiculous.

Of course there’s more nuance than what you read as a guide from BRS or where ever. UV causes DNA breaks. Some breaks are bad for survival or reproduction, some aren’t. Many are in between, they are bad in certain combinations. So the more UV exposure the more likely to get the desired effect. It’s a LD50 (dose that causes 50% to die or be unable to reproduce), or LD75, or whatever. There’s no such thing as LD100, practically speaking. People arbitrarily decide what kill rate is the target, and that’s how they decide what the exposure in amount of UV light per surface area should be. Organisms also can fix the breaks at a certain rate, so you are better off delivering the dose in 1 session or a couple sessions than microdosing, but either can work. The other complication is that UV-C (the one we are talking about) doesn’t penetrate tissue well, so multicellular organisms like parasites need a higher dose to penetrate multiple layers.

The UV sterilizers generally get longer as they get stronger, so having 2 in series is almost exactly the same as 1 larger one of twice the wattage. It doesn’t matter if there’s a little tubing between them. Having them in parallel but both in the same chamber in the sump is very similar (but not exactly the same) since a lot of the water coming through will get the double dose as it does. Taking your extreme example of having very high water flow and having all the water go through the UV every hour could be effective, depending on how quickly different organisms take to fix DNA breaks, but it’s less practical.
 
richiev said:
If you pump water though two in series at 600gph, that's the same amount of dwell time as water going through two in parallel at 300gph.

There's two roads that are 30 miles long running parallel to each other. The speed limit is 30mph. I send a car down each road. The cars will dwell on the roads for 1 hour.

There's a road that is 60miles long, which is made up of two 30 mile long segments. I send a car down it at 60mph. The car will dwell on that road for 1 hour.

Turns out all those cars are convertibles with the tops down. Bald old men are driving, with their partners sunbathing in the back seat. Everyone comes out with an increase in melanomas.
Click to expand...

That's assuming that the cars go on each road and don't take a detour and promise to immediately make a u-turn and go back through one of the two roads before going somewhere else on one of the non-designated roads....
 
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