UV & Flow

phatduckk

Active member
Hi all,

So I’ve started to look into a UV unit. Seems good to have. I’ve read great things about the algae control and also have learned that it can help with various bacteria.

Sounds cool... question is, how much flow? I’ve been doing a bit of reading and see people mention about 2-3x turnover of the tank. But again they never specify what that is targeting.

furthermore, looking at the Pentair units, the BRS site recommends 79gph for protazoa and bacteria and & 470gph for algae. On the flip side the UV Aqua manual recommends something crazy like 1200gph for their 25w unit for a “reef tank”.

so my question is: wtf?

LoL Assuming a 90g volume of water & a 25w unit (probably Aqua UV) what flow rates should I target for Protozoa/bacteria & algae?

1200 sounds like an insane amount. I chatted with and called Aqua UV support to verify and both agents recommended 1200gph. On the other hand everyone on reef forums, brs support and marine depot support all recommended 400gph

confused I am
 

phatduckk

Active member
I have an 57w Aqua UV on my 75g tank. I'm feeding it with a MJ1200 pump, so approx. 400gph...this cleared out ostreopsis dinos for me and really cleaned up the tank.
ya I was thinking the 25w as its rated for 150g and mine is about 90. for nerd reasons I'm thinking a DC pump and an apex flow meter so I can have it decently dialed in. Just trying to find out the target rate as there's massive discrepancies in everything I'm reading.

there's gotta be some equation out there to figure out desired flow based on wattage & volume etc. That plus a chart stating what dies at which μw/cm2 value would be ideal
 

phatduckk

Active member
OK here's some info to help clarify the point...

This chart is from the Aqua UV manual:

1165


That combined with this quote from https://www.theaquariumsolution.com/uv-kill-whitespot seems to clarify things:

For water clarity we suggest a U.V intensity of 30,000 microwatt's/sec/sq.cm and our U.V sterilisers are designed to deliver this at the quoted flow/contact rate through the unit...

When trying to kill the white spot parasite ... a greater U.V intensity of 72,000 microwatt's/sec/sq.cm is required to kill it.
So seems like like Aqua UV & The Aquarium Solution agree on the target microwatt's/sec/sq.cm for the 2 different use cases.

Now - the question is: why does the BRS page for Pentair 25w quote 79 & 472 GPH for the same job? Are the units' design so different that they require a massively different flow rate...

Or all all reefers on forum doing it wrong? heh... Let me see if I can dig up some info from Pentair's docs... brb
 

phatduckk

Active member
OK so Pentair's manual also states that 30,000 microwatt's/sec/sq.cm is required for algae and bacteria.
According to their chart @ 25w that equates to 472gph (compared to 1200 w/ Aqua UV)

1167


So it seems like the Pentair specs are the ones most commonly references in forums posts - even if folks are using an Aqua UV unit. So are a ton of people actually using their Aqua UV units improperly? Folks are claiming successful results (clearer water, Dinos going away etc) so what gives? Are the designs of these units so different that the Aqua UV requires 3x the flow of the Pentair?
 

mattzang

Active member
I have an 57w Aqua UV on my 75g tank. I'm feeding it with a MJ1200 pump, so approx. 400gph...this cleared out ostreopsis dinos for me and really cleaned up the tank.
do you have it in your sump or just directly in the tank?

i've been battling the dinos for awhile and they suck. UV sterilizers seem expensive, but man i might just get one to rid myself of this headache in the future. although i need to try the 3 day blackout first as that's slightly more economical
 

phatduckk

Active member
do you have it in your sump or just directly in the tank?

i've been battling the dinos for awhile and they suck. UV sterilizers seem expensive, but man i might just get one to rid myself of this headache in the future. although i need to try the 3 day blackout first as that's slightly more economical
I have Dino’s in my 10g frag tank. I bought the little AIO unit they sell for IM tanks and it definitely has been a huge help. I still siphon some up daily using a coral feeding baster thing.

In my new UV reading (it’s been a few hours so I’m no expert) it seems folks suggest pluming in & out of the DT for Dino’s as opposed to the sump.

then again, that would only impact the water born variety (I believe there’s 3 types)
 

Idoc

Member
ya I was thinking the 25w as its rated for 150g and mine is about 90. for nerd reasons I'm thinking a DC pump and an apex flow meter so I can have it decently dialed in. Just trying to find out the target rate as there's massive discrepancies in everything I'm reading.

there's gotta be some equation out there to figure out desired flow based on wattage & volume etc. That plus a chart stating what dies at which μw/cm2 value would be ideal
I was initially wanting a 25w Aqua UV, but someone locally just happened to be selling a 57w version for $150, so I couldn't pass up that deal. I see from your other post that you found the chart on the Aqua UV website that shows flow rates for saltwater tanks...
 

Idoc

Member
OK so Pentair's manual also states that 30,000 microwatt's/sec/sq.cm is required for algae and bacteria.
According to their chart @ 25w that equates to 472gph (compared to 1200 w/ Aqua UV)

View attachment 1167

So it seems like the Pentair specs are the ones most commonly references in forums posts - even if folks are using an Aqua UV unit. So are a ton of people actually using their Aqua UV units improperly? Folks are claiming successful results (clearer water, Dinos going away etc) so what gives? Are the designs of these units so different that the Aqua UV requires 3x the flow of the Pentair?
Call the Aqua UV support staff and ask this very question to see what their answer would be for this. I called them about a bulb issue and they were very helpful and extremely nice.
 

Idoc

Member
do you have it in your sump or just directly in the tank?

i've been battling the dinos for awhile and they suck. UV sterilizers seem expensive, but man i might just get one to rid myself of this headache in the future. although i need to try the 3 day blackout first as that's slightly more economical
I have mine plumbed directly into my DT...pulling from an MJ1200 pump in the DT and returning back into the DT.

I initially had small cell amphidinium dinos that were miserable with only a small area on a rock with some ostreopsis dinos. Then I did the Elegant Corals dino treatment and that wiped out my small cell amphidinium dinos, but then for some reason the ostreopsis took hold a few weeks later! So, I hooked up the UV sterilizer...Ostreopsis gone in a couple of days! UV works, but depends on the type of dino you have present.
 

mggray87

Well-known member
so far UV isnt doing anything for cyano... as it thrives while my 57w is pumping.. so in terms of that bacteria.. nada...... but ive read dinos gets demolished by UV
 

Idoc

Member
so far UV isnt doing anything for cyano... as it thrives while my 57w is pumping.. so in terms of that bacteria.. nada...... but ive read dinos gets demolished by UV
I think it helps with my cyano some...but it doesn't make it go away! I've had mine turned off for the past couple of weeks just to see if my dinos would return with a vengeance...so far, no!
 

Mrpizzaface

New member
I have been told pentaire uses a much more conservative flow to wattage ratio, and that I should use their ratio to determine the correct flow rate regardless of the manufacturer.
 

phatduckk

Active member
I have been told pentaire uses a much more conservative flow to wattage ratio, and that I should use their ratio to determine the correct flow rate regardless of the manufacturer.
seems that matches up with all the stuff I read on forums. I wonder why... Aqua UV seems like a reputable company, why would they be so “wrong”?
 
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