UV Plumbing Question

Short Reefer · Jan 30, 2023

Saltyanimals said:
good discussion here everyone. I'm with @DanyL on the key is to be able to tune the water flow through the UV according to the manufacture and target objective of parasite or algae solution. Respectively it's not a set GPM number as multiple variables come into play such as your pipe size, bulb size thus contact time required for your objective etc. BRS has a nice comparison on the 2 solutions which is outside of this discussion.

I struggled with my manifold design which also feeds the UV for the same constraints. I can't sufficiently control the flow rate through the UV to my satisfaction and I also went ahead and made sure I return the UV output as a PVC "wye" upstream of the manifold to maximize UV'ed water to DT and not a circulation within the sump.

I see some photos of the apex flow meter like @VNReef1 . How is that working for you? Do you trust it enough when using it to tune flow rate? I've ready they're unreliable thus never went down that route.

@Saltyanimals its working perfectly in my case. I can adjust to amount gph i want for fish or full blast for algae by adjusting the gate valve.

srobertb · Jan 30, 2023

VNReef1 said:
@Saltyanimals its working perfectly in my case. I can adjust to amount gph i want for fish or full blast for algae by adjusting the gate valve.

Flow meters are a mixed bag from what I’ve read and seen. I have been (quite successfully) using a 1/4” version on my ATO line. It has proven invaluable as I can just look at it at a glance and see if my ATO is running too much or not at all over time. So, with RO/DI water…they’re flawless. Is it accurate? No clue.

I am purchasing for a new tank right now and was going to add a 2” to my return and overflows. I was talked out of using them on the overflows and I am leaning towards not adding to my return.

I think the question of “how clean is your return water” is so varied and leads to the mixed reviews. I’m hopeful my answer will be “more clean than average” but I run a large refugium as my primary filtration method.

They’re also absolutely flow killers from what I read. Seemingly by 10-20%.

I will keep it on my ATO line, and I am thinking of adding one to each manifold, but I think you want the cleanest most filtered water running through them as possible so you’ll have to answer that along with if you can spare the flow.

Short Reefer · Jan 30, 2023

srobertb said:
Flow meters are a mixed bag from what I’ve read and seen. I have been (quite successfully) using a 1/4” version on my ATO line. It has proven invaluable as I can just look at it at a glance and see if my ATO is running too much or not at all over time. So, with RO/DI water…they’re flawless. Is it accurate? No clue.

I am purchasing for a new tank right now and was going to add a 2” to my return and overflows. I was talked out of using them on the overflows and I am leaning towards not adding to my return.

I think the question of “how clean is your return water” is so varied and leads to the mixed reviews. I’m hopeful my answer will be “more clean than average” but I run a large refugium as my primary filtration method.

They’re also absolutely flow killers from what I read. Seemingly by 10-20%.

I will keep it on my ATO line, and I am thinking of adding one to each manifold, but I think you want the cleanest most filtered water running through them as possible so you’ll have to answer that along with if you can spare the flow.

tbh,
if the flow meter tolerance of +/- 100gph, i wouldnt complaint. It does the job better than run blind.

Glott3133 · Jan 30, 2023

srobertb said:
Flow meters are a mixed bag from what I’ve read and seen. I have been (quite successfully) using a 1/4” version on my ATO line. It has proven invaluable as I can just look at it at a glance and see if my ATO is running too much or not at all over time. So, with RO/DI water…they’re flawless. Is it accurate? No clue.

I am purchasing for a new tank right now and was going to add a 2” to my return and overflows. I was talked out of using them on the overflows and I am leaning towards not adding to my return.

I think the question of “how clean is your return water” is so varied and leads to the mixed reviews. I’m hopeful my answer will be “more clean than average” but I run a large refugium as my primary filtration method.

They’re also absolutely flow killers from what I read. Seemingly by 10-20%.

I will keep it on my ATO line, and I am thinking of adding one to each manifold, but I think you want the cleanest most filtered water running through them as possible so you’ll have to answer that along with if you can spare the flow.

I tee'd my UV off of my main return. With the connections that came with he 25W Aqua Ultraviolet UV, I had to reduce the line from 1" to 3/4" and then back up to 1". I also attached a gate valve on the main return just above the tee, to force water through the UV. The flow valve won't go above 200GPH in my case. So I don't know if the flow gate is completely wrong, or I can't force enough water through the UV to get up to 800GPH.

When I pulled the line off of the output side of the UV, the water is flowing very hard, but not sure of the GPH.

I even turned my Vortec L2 to 75% to try to get more.

Very frustrating.

Saltyanimals · Jan 30, 2023

Glott3133 said:
I tee'd my UV off of my main return. With the connections that came with he 25W Aqua Ultraviolet UV, I had to reduce the line from 1" to 3/4" and then back up to 1". I also attached a gate valve on the main return just above the tee, to force water through the UV. The flow valve won't go above 200GPH in my case. So I don't know if the flow gate is completely wrong, or I can't force enough water through the UV to get up to 800GPH.

When I pulled the line off of the output side of the UV, the water is flowing very hard, but not sure of the GPH.

I even turned my Vortec L2 to 75% to try to get more.

Very frustrating.

I did the same with reducing down to 3/4 in and out of my Aqua 57W just to make it play with the rest of my manifold plumbing which is all 3/4. I also tee'd off my return pump for that manifold, but I noticed that I need to reduce the upstream gatevalue to force more water through the manifold and UV. Running it wide open seems to reduce the flow through the UV because water takes the path of least resistance.

I think I need to redo my manifold and UV putting a little more thought into controls to redirect flow where I need to. Will likely do the apex flow sensor as @VNReef1 shared his benefits. I just heard little confidence in the accuracy of the flow meter and additional disadvantage is reduction in overall flow through it, but in this application it's probably okay since we're only increase the contact time with the UV bulb anyways.

Short Reefer · Jan 30, 2023

Running L2 as Return. Half Open Gate valve will max out at 330gph for UV 65% L2.
1500gph with closed gate valve.

This method will let you run either for algaes or fish.

mnl119 · Jan 30, 2023

I've often wondered if constructing a manifold and branching flow through a UV is worth the complexity. I understand the desire to slow water through the UV to increase dose to a lethal level, but those numbers we've all seen are for once-through systems and our aquariums are cycled over and over.

To explain, let's consider 2 examples. In example A, we bypass the UV with 80% of the flow thus achieving what I'll call a Lethal Dose (LD) through the UV with 20% of the flow. In example B, we just send 100% of the flow through the UV achieving 0.2LD on each pass.

Now let's assume we have a 5x hourly turnover rate of the tank and consider 1 hour. In example A, we have treated (1-0.8^5) of the water with at least 1 LD, and 33% of the water remains untreated. In example B, we have treated 100% of the water with a LD (5*0.2LD), albeit in a more chronic way than in example A.

Anyone care to explain? In order to really answer the question experiments are probably needed where the same tank is run in both modes and pathogen counts would be required.

Saltyanimals · Feb 1, 2023

mnl119 said:
I've often wondered if constructing a manifold and branching flow through a UV is worth the complexity. I understand the desire to slow water through the UV to increase dose to a lethal level, but those numbers we've all seen are for once-through systems and our aquariums are cycled over and over.

To explain, let's consider 2 examples. In example A, we bypass the UV with 80% of the flow thus achieving what I'll call a Lethal Dose (LD) through the UV with 20% of the flow. In example B, we just send 100% of the flow through the UV achieving 0.2LD on each pass.

Now let's assume we have a 5x hourly turnover rate of the tank and consider 1 hour. In example A, we have treated (1-0.8^5) of the water with at least 1 LD, and 33% of the water remains untreated. In example B, we have treated 100% of the water with a LD (5*0.2LD), albeit in a more chronic way than in example A.

Anyone care to explain? In order to really answer the question experiments are probably needed where the same tank is run in both modes and pathogen counts would be required.

Good question and I've gone down the same question before. I don't think anyone can properly do a pathogen count experiment successfully between those scenarios. Boils down to a question of efficiency. Sure you're going to turn over 5x of UV'ed water, but that's all within the sump. What you're not able to easily quantified is how much of that highly UV'ed sump water gets to the DT.

I'll give you an interesting example. Antidotal, but I can see a bit of correlation. I introduced a powder blue to my tank. It went into my sump which was running the UV exiting back to the sump before I was able to properly plumbed back into the return line. The tang sat there for over a week doing well acclimating to the tank. Looking good eating well etc. It quickly showed ich shortly after I introduced it into DT. That was a head scratcher for me and lead me down the research to understand why. That's where I stumbled upon a higher UV'ed sump water vs DT water discussion somewhere. It further highlighted that some of the parasites live closer to the sand thus a typical top overflow may not move the parasites through the UV making some folks go out of the way to plumb some of that lower water through a UV. This made me look closely at my tank and I actually do see drain vents at the bottom back of my tank suggesting that my tank does get some of the water from lower half. Maybe this was intentional in my tank design bonus.

That discussion lead me to go ahead and add that wye into my return line for the UV for my own piece of mind. I want to say there was a BRS UV video that mentioned this too.

mnl119 · Feb 1, 2023

Saltyanimals said:
Good question and I've gone down the same question before. I don't think anyone can properly do a pathogen count experiment successfully between those scenarios. Boils down to a question of efficiency. Sure you're going to turn over 5x of UV'ed water, but that's all within the sump. What you're not able to easily quantified is how much of that highly UV'ed sump water gets to the DT.

I'll give you an interesting example. Antidotal, but I can see a bit of correlation. I introduced a powder blue to my tank. It went into my sump which was running the UV exiting back to the sump before I was able to properly plumbed back into the return line. The tang sat there for over a week doing well acclimating to the tank. Looking good eating well etc. It quickly showed ich shortly after I introduced it into DT. That was a head scratcher for me and lead me down the research to understand why. That's where I stumbled upon a higher UV'ed sump water vs DT water discussion somewhere. It further highlighted that some of the parasites live closer to the sand thus a typical top overflow may not move the parasites through the UV making some folks go out of the way to plumb some of that lower water through a UV. This made me look closely at my tank and I actually do see drain vents at the bottom back of my tank suggesting that my tank does get some of the water from lower half. Maybe this was intentional in my tank design bonus.

That discussion lead me to go ahead and add that wye into my return line for the UV for my own piece of mind. I want to say there was a BRS UV video that mentioned this too.

Your anecdotal evidence highlights another important issue... how treated water gets mixed throughout the system. Are there dead zones in the Display Tank (DT) that negate the whole UV concept? My simple examples can't capture something like that because, well, they're too simple.

I just make the suggestion because every so often we see these posts where people are adding all this complexity (bypass loops, control valves, back flow preventers, flow meters, etc...) when we don't even know if they are doing any good because we are applying dose numbers from a situation that doesn't even apply.

I submit that the money for all that complexity may be better spent by just adding a second, or third, or array of more UV sterilizers so that the return flow to the DT does meet the once-through dose numbers for whatever outcome is desired (e.g., algae kill, bacteria kill, parasite kill).