UV Sterilizer setup 75g FOWLR

[mad1ben2]

I have approximately an 80 gal FOWLR system (75g tank with sump) and want to add UV primarily for parasite control. I've read and understand slower flow is needed for parasite control while faster flow is needed for algae control... I also understand using an oversized unit with proper flow rate might accomplish both. I don't have algae issues (did go through red cyano issue but was able to resolve that) but would be nice to keep ahead of potential issues and reduced glass cleaning would be very welcomed! I've read some say oversized UV will overheat the tank, etc... Hoping you can help me with my set up so I get the results I want without creating new problems... thanks in advance for you help!

I have a Jebao STU-55 (55 watt) available to me and I'm hoping with the right flow rate I can gain advantages with parasite and algae control. I plan to place this in my sump area pulling water from filter sock section and dumping into return section.

Questions:
1. Will this unit work for my system? Too large? I'm not aware that you can over sterilize water (right?) but I don't want over-heating issues?
2. What would the ideal flow rate be?
3. Any other things I need to worry about?

Thanks again!

System overview:
* 75 gal FOWLR display with ~30 gal sump (~15 gal actual water in sump) / Filter socks on overflow (bean animal), Reef Octopus 110-int in first section, cheato with LR in middle section (not reverse lighted), then return section (single pump - dual returns) / basic marine 4' LED light
* Tank is 7-8months young with LR from established tank / 1-2" sand bed / med-heavy bio-load / all fish QT'd via Humblefish's copper power-metro-medicated food 2-tank method
* Temp 78 F / Salinity 1.025 / run carbon and GFO as needed / nitrates and phosphates stable but run a bit high @ 20ppm and 0.25-0.5ppm / feed 2x daily / change filter socks every 3 days / slack on water changes

 

[Quietman]

Is that the stainless steel version? That's designed for FW ponds. I believe they sell a PVC one of same size.

Ideal rate depends on exposure levels. I haven't found UV exposure in a cursory look at Jebao info. Exposure is based the spectrum of UV light source, intensity, and of course flow. There's also a degradation component as UV light source will degrade over time.

Without that it's hard to provide flow rates.

Your thinking is correct that with smaller tank sizes it's practical to use one filter and run it so your accomplishing both algae and pathogens control.

Running UV off sump isn't as effective as closed loop off DT especially for algae.

 

[mad1ben2]

Yes, the stainless version. Brand new bulb ordered from CNZ.

Makes sense that I'd get better results with a closed loop in display. Prefer to keep additional equipment out of display but will consider changing if I don't get desired results with it in the sump. But want to make sure I have flow rate figured out before I blame poor results on location.

 

[mad1ben2]

Ok, so after more research I found a very detailed article by American Aquarium Products. They discuss 3 levels of uv sterilization (Clarification, Level 1, and Level 2 - Level 2 being the highest) and 3 categories of sterilizers (A - highest grade, B - mid grade, and C - economy grade like my Jebao STU55).

The gist is that to achieve higher sterilization you have to slow flow rate and still achieve proper turnover rate. Turnover rate is constant for each sterilization level but higher flow rates can be used with higher quality units.

They did say that L2 sterilization cannot be achieved with CatC units.

I'll skip the numbers for Clarification sterilization and start with Level 1:

LEVEL 1
To achieve L1 with CatA unit you need 30-35 gph per watt and 1-1.5 turnover per hour of tank volume.

To achieve L1 with CatB unit you need 20-30 gph per watt and 1-1.5 turnover per hour of tank volume.

To achieve L1 with CatC unit you need 15-20 gph per watt and 1-1.5 turnover per hour of tank volume.

So, to achieve L1 with my 55watt CatC unit I need 825 gph (15 gph per watt x 55 watts) which easily achieves the 1-1.5 per hour required turnover rate for my 80 gal system (I would actually get a 10 times per hour turnover).

LEVEL 2
To achieve L2 with CatA unit you need 10-12 gph per watt and 2.5-3 turnover per hour of tank volume.

To achieve L2 with CatB unit you need less than 8 gph per watt and 2.5-3 turnover per hour of tank volume.

They did not explain why you cannot achieve L2 with a CatC unit but I would presume it would be because it's unlikely that you can slow the flow rate enough while still achieving the required tank turnover rate. There may be additional reasons like bulb quality included with economy units, build quality, etc.

In order to get as close to L2 as I can, I've dropped my flow to 4 gph per watt and I can still achieve 2.75 turnover rate.

4gph per watt x 55watts = 220gph

80gal x 2.75 turnover = 220gal

I've had this set up for 24 hrs and I've noticed an almost 2 deg rise in tank temperature (77-79F). If this becomes an issue I'll either raise the flow rate (reducing sterilization level) or setup the UV unit to come on and off at different times of the day. I'd guess a higher sterilization rate that wasn't run 24/7 would be better than a lower sterilization rate that runs 24/7 but I'm not certain. Also I'd guess it would be harder on the unit (bulb, ballast, etc) to turn it on/off multiple times a day.

Well if you got this far thanks... I posted my question but didn't get many responses so I'm guessing this is a relatively unique approach. Just thought I'd share my thoughts...