UV Sterilizer usage with wall to wall rear over flow

[squarereefer]

Well everyone, I learned today that I have probably been wasting time and effort with my UV sterilizer the last few years by running it 24/7, doing my best to ensure proper flow, and changing the bulb yearly.

The issue is that I have an innovative marine INT75 tank with the full "coast to coast" over flow along the back. I also have to keep the lid secure to keep the fish in and the cats out. I run a Trigger Triton v2 20 sump, and have always had the UV running from a Sicce pump that sits in the skimmer chamber and returning sterilized water to the return chamber in hopes that most of it is making it back up to to DT quickly.

Scrolling YouTube, I ran across an older BRS video that referenced UV treated water should be returned to the DT and that doing what I am doing is basically just sterilizing the same water over and over. Doing some googling, I found a lot of similar sentiment around the various forums.

Has anyone seen a creative way to return water to the main DT when the only open space is the rear overflow? My sterilizer is technically a HOB design, so I could hang it on the rear, but returning straight into the over flow would be mostly the same as what I am doing today, right?

 

[BryanM]

Mine is just plumbed inline, apparently not ideal, but it works for me. Return pump pumps water in from my return chamber through the UV, exists the UV up to the tank.

 

[mmorrison55]

Same… UV is plumbed just before one of my returns.

 

[Privateye]

Honestly, having UV return to the DT is kind of an anecdotal suggestion from what I've seen. Some claim this is the key to treating dinos (maybe it helps in that case - I haven't tried the DT to DT method) but this isn't something set it stone. No UV manufacturer states this must be done, or even suggests it (to my knowledge). And I've seen a lot of dinos in systems that send water from the sump, to the filter, to the UV, then to the DT.

What you do want is to send clean water through the unit. So it should draw water from somewhere after your mechanical filter. Often times this is the sump. And often times people send it directly back to the tank using their main pump. They send some of the water through the UV, and any excess through a bypass. One pump does both jobs instead of purchasing a dedicated pump for the UV. A dedicated pump can make the flow rate easier to dial-in though.

The real thing you want to focus on, as you mentioned, is not sending the same water through the UV over and over instead of the other water. So you wouldn't want it to discharge to the chamber it draws from. You also wouldn't want to take it from the "end" of your sump and put it back to the "front". You could do the opposite though.

Can you (or someone) link that BRS video? I haven't seen it yet.

I'd be happy to review your UV to see if it was properly-sized for your goals if you like. I just need to know the model and the flow rate (if known). I see your system volume is 75 gallons and your UV transmittance is likely over 90%.

 

[squarereefer]

Mine is just plumbed inline, apparently not ideal, but it works for me. Return pump pumps water in from my return chamber through the UV, exists the UV up to the tank.

Am I picturing this correctly that you have the return line/pipe coming from the return pump - pumping water into the UV and then the output going back to that same return line/pipe en route two the DT? I could definitely feed the UV from the return pump but for some reason I thought feeding it back into the return line would be a bad idea or at least create way to much restriction on the return.

My return pump is a COR15 that I don't run at 100% , so I could probably turn it up and make this work.

 

[mcarroll]

Not bypassing water is common advice that comes straight from the manufacturers – send everything through UV – *but* you can only know if you read the manual.

Here is AquaUV's manual: https://aquaultraviolet.com/pages/faq#manuals

AquaUV puts it in the manual at least twice. Once in diagram form and once in the manual's FAQ just to make sure it's clear.

The exceptions where this would not be pointed out would be cheapie UV units that are marketed toward algae control. But you can work around their intended use by oversizing and running the unit directly in the display while it's needed.

I run a Trigger Triton v2 20 sump, and have always had the UV running from a Sicce pump that sits in the skimmer chamber and returning sterilized water to the return chamber in hopes that most of it is making it back up to to DT quickly.

Plumbing it into the return line would still be more ideal, but what you have seems like a decent workaround. I wouldn't say you've been wasting anything.

The downside that I see with the workaround is that your quartz tube might need cleaning more frequently than it would if it was getting fully filtered water from your return pump.

So your UV might not have been as effective as you thought it to be just because the quartz tube might be dirty.....but you can check that. If it's fine, then there's no real downside to your workaround IMO.

Putting a sponge that you clean regularly on the input of your Sicce UV pump would help.

 

[BryanM]

Am I picturing this correctly that you have the return line/pipe coming from the return pump - pumping water into the UV and then the output going back to that same return line/pipe en route two the DT? I could definitely feed the UV from the return pump but for some reason I thought feeding it back into the return line would be a bad idea or at least create way to much restriction on the return.

My return pump is a COR15 that I don't run at 100% , so I could probably turn it up and make this work.

My UV is a pentair 40, it is quite sizable, and I did not feel it restricted anything.

I run a cor-20 return pump, so pretty close to you.

 

[squarereefer]

Not bypassing water is common advice that comes straight from the manufacturers – send everything through UV – *but* you can only know if you read the manual.

Here is AquaUV's manual: https://aquaultraviolet.com/pages/faq#manuals

AquaUV puts it in the manual at least twice. Once in diagram form and once in the manual's FAQ just to make sure it's clear.

The exceptions where this would not be pointed out would be cheapie UV units that are marketed toward algae control. But you can work around their intended use by oversizing and running the unit directly in the display while it's needed.

Plumbing it into the return line would still be more ideal, but what you have seems like a decent workaround. I wouldn't say you've been wasting anything.

The downside that I see with the workaround is that your quartz tube might need cleaning more frequently than it would if it was getting fully filtered water from your return pump.

So your UV might not have been as effective as you thought it to be just because the quartz tube might be dirty.....but you can check that. If it's fine, then there's no real downside to your workaround IMO.

Putting a sponge that you clean regularly on the input of your Sicce UV pump would help.

Thanks! I am running the Aqua UV 8w advantage myself. I might try to plumb into my return pump this weekend.

 

[Privateye]

Not bypassing water is common advice that comes straight from the manufacturers – send everything through UV – *but* you can only know if you read the manual.

Here is AquaUV's manual: https://aquaultraviolet.com/pages/faq#manuals

AquaUV puts it in the manual at least twice. Once in diagram form and once in the manual's FAQ just to make sure it's clear.

The exceptions where this would not be pointed out would be cheapie UV units that are marketed toward algae control. But you can work around their intended use by oversizing and running the unit directly in the display while it's needed.

Careful with this one. IME Aqua UV isn't exactly the most-knowledgeable when it comes to UV technology (at least not their sales and tech support people). Here's the line from their manual:

That statement basically means nothing. If your existing flow rate exceeds the flow rate the unit is rated for, then you would have to use the bypass method to make it effective. Or buy a different pump. This sentence reads more like "Do not worry! It is great product! You will be very happy!"

So let's look at a manual from Pentair (adapted from Emperor Aquatics, who originally developed the Smart UVs). You'll see things like this:

Saying that you should not do this indicates a lack of understanding. So it's not that this comes from "the UV manufacturers", it just came from Aqua UV. Take it with a grain of salt.

 

[squarereefer]

Careful with this one. IME Aqua UV isn't exactly the most-knowledgeable when it comes to UV technology (at least not their sales and tech support people). Here's the line from their manual:

That statement basically means nothing. If your existing flow rate exceeds the flow rate the unit is rated for, then you would have to use the bypass method to make it effective. Or buy a different pump. This sentence reads more like "Do not worry! It is great product! You will be very happy!"

So let's look at a manual from Pentair (adapted from Emperor Aquatics, who originally developed the Smart UVs). You'll see things like this:

Saying that you should not do this indicates a lack of understanding. So it's not that this comes from "the UV manufacturers", it just came from Aqua UV. Take it with a grain of salt.

I think you may be on to something with Aqua UV's knowledge. I have found their support very helpful when chatting, but unsure about accuracy. They insist that for my 75g tank, the 8w is more than enough and should be run at ~425 GPH for algae control and water clarity. Most sources I see online significantly less flow.

Following their guidelines, I have it hooked up to a Sicce Synca 3 right now, dialed in at about 400 gph going into the sterilizer, but due to flow restriction within the UV unit, I am only getting 250 gph back out. Does that sound reasonable? I've always felt it was way too much flow, but wanted to follow the manufacturers recommendations.

 

[Privateye]

I think you may be on to something with Aqua UV's knowledge. I have found their support very helpful when chatting, but unsure about accuracy. They insist that for my 75g tank, the 8w is more than enough and should be run at ~425 GPH for algae control and water clarity. Most sources I see online significantly less flow.

Following their guidelines, I have it hooked up to a Sicce Synca 3 right now, dialed in at about 400 gph going into the sterilizer, but due to flow restriction within the UV unit, I am only getting 250 gph back out. Does that sound reasonable? I've always felt it was way too much flow, but wanted to follow the manufacturers recommendations.

I think that 425 GPH with that UV would be sufficient, assuming these numbers are accurate:

I've noticed that Aqua UV tends to have higher UV doses for a given wattage of lamp than competing brands. I know with regards to Pentair some of that comes from UV transmittance (UVT). Pentair assumes 90% UVT as a safety factor, but Aqua UV assumes 100% (they told me this over the phone). UVT and UV dose isn't a linear relationship. However, it doesn't explain all of the difference so I can't really speculate as to why the doses are higher.

You reminded me of one thing they have often said in the past though: "you can get a UV to control algae or parasites, but not both". Which is incorrect.

When treating algae and bacteria generally a higher flow rate is desired because they can proliferate quickly. It may do the job at your current flow rate, or higher could be better. It kind of depends on what's happening in the tank. With a unit that small I could see it impacting flow rate, especially with a mag drive pump. Mag drives don't put out much pressure compared to centrifugal pumps because the impeller isn't connected to the motor by a shaft. Magnetism just isn't as strong.

So they want you to actually have 425 GPH going through the UV. What would be nice is if they had a table or graph showing the pressure drop through the unit. That way you can match it to your pump curve to determine whether the pump is suitable before you buy it. For larger UVs this isn't an issue. In this industry we're often adapting our UVs to smaller pipe/hose diameters, meaning the UV isn't the most-restrictive part of the plumbing.