Pump volume for UV Sterilizer

[haimi]

need advise on using a UV Sterilizer on a 2ft tank. Got a 9W uv that is directly fed from a 900 l/hr pump. Is this effective?

Heard that the efficiency of a UV relies on the contact period of the water in the UV tube. With the current flow rate, the contact time is quite short. not sure how efficient this will be. Please advise. Thanks

[haimi]

anyone can help me on this? Thx

[CFOh]

anyone can help me on this? Thx

What brand is it? check the spec.. I browse a few website... how to interpret the spec... for example brand "TERMINATOR 9 WATT QUARTZ UV STERILIZER" suggested range 225/360 gph (suggested/maximum) which is 851/1362 l/hr.....

*Suggested flow rates are based on "end of lamp's life" performance (80% power)

*Maximum flow rates are based on new lamp output (100% power)

*Flow rates consider 90% UV transmissibility

Another approach, a few website recommend 1Watt = 10gph (37.9l/hr) after some understanding found this were due to the intention of so called "level two Sterilization (Parasites, “Stubborn” Viruses; Recommended for Swimming Pools)"

Pls find table below:

your 900l/hr should be under "Level One Sterilization (Bacteria, some Virus)" but need to ensure fulfill 1.5 times per hour water turn over rate...

Very good articles explain on UV flow can find below:

http://americanaquariumproducts.com/AquariumUVSterilization.html

Water Flow/Contact

This is easily the most important simple aspect of proper UV Sterilizer set up and all the gimmicks (like “twists” and “wipers”) will not help a poorly installed UV with high flow rates of water passing through. In fact this is where most UV Sterilizers installed in ponds fall well short as pond keepers will place for instance a 9 watt UV with a 1000 gph pump which is 2-4 times the effective flow rate for a pond installation (often as per very poor directions by the manufacturer). This problem is also common among reef aquarists with high flow rate sump pumps attached to UV Sterilizers incompatible with the flow rate, resulting in the common and incorrect statement that “the UV Sterilizer was useless”.

Admittedly flow rate is a generalization expressed to simply mW/cm2 that is absorbed/transmitted to pathogens/algae (please read further in this article for more in depth explanation of UVC Penetration/mW/cm2). I use this method as simplified method that has tested well over the years in my applications of UV Sterilizers. Obviously there are other factors such as distance from the UV wall, water turbidity, quartz sleeve cleanliness, UV bulb condition/age, and more (again that are explained in this article).

As well many UV manufacturers will over state their UV Sterilizer abilities as per maximum flow rates (although this does not necessarily make such a UV Sterilizer a poor/inferior product as some other web sites claim, I would only use the simple calculations provided here to make your choice, not exaggerated claims by many UV manufacturers).

• The key to success is CORRECT water flow, cleanliness of the bulb and/or quartz sleeve, water particulates and water temperature.

Please also see the table at the end of this section that further explains flow for Sterilization or clarification for aquariums, ponds or even pools

Also please note that the given flow rates are generalizations, with many Compact UV Sterilizers requiring the slower flow rate given over a Standard length UV (such as the TMC Pond Advantage/Vecton)

*As a Sterilizer; Generally for bacterial control (& many virus) a flow rate of 20-25 gph per watt (75-95 liters per hour, per watt).

*As a Clarifier; For algae control, 40 gph per watt (sometimes as high as 50 gph) is effective to maintain effective exposure for effective UVC sterilization/radiation (depending on model UV’s design).

*As a Sterilizer; For single cell parasite control (such as Cryptocaryon) as well as a few “stubborn” viruses, a flow under 10 gph (or even less) is necessary. This is often not 100% for all parasites of this type, so a UV Sterilizer should not be relied on as the sole preventative for these parasites!

Please see the section (“What Size UV Is Best”) further down in the article for more about flow rate. Admittedly this is a VERY basic and simplistic rule, with other factors such flow design, interior wall gap from UV bulb, & even actually output of UVC per watt (Versus other wave lengths).

*The design of the unit should only allow a gap of .3 cm or less between the bulb or quartz sleeve and the wall of the unit for effective contact and temperature.

This is where canister aquarium and pressurized pond filters (such as the Aquael, Nursery Pro, even the newer Via Aqua) fail miserably as there is too large a gap and in general a poor flow design around the bulb/quartz sleeve (as well as flow rates far exceeding UVC bulb wattage capabilities)

• When figuring the flow (gph) of a water pump, consider the flow of water AFTER it passes through the UV clarifier and reaches the aquarium or top of water feature in a pond. For instance water pump or filter rated at 400 gph at 0 head pressure & 6 feet maximum head pressure (which is how all pumps are rated), will likely only push about 200 gph after being lifted 3 feet from a sump or up a water feature.

For a positive check of flow rate, simply use a stop watch (many cell phones have this feature), and place a container under the outlet. For example if one gallon is filled within 10 seconds, this is 6 gallons per minute or 360 gph. Many persons are surprised how slow their pump actually is after applying head pressure.

Some pumps or filters lose head pressure more quickly than others (such as the Hagen Fluval), while other pumps are specifically designed to maintain higher head pressure over greater vertical distances (such as the Rio HF Series pumps).

Size of pipe/tubing on water flow:

Another consideration is the size of the PVC pipe or tubing coming from the pump. For instance a pump with a 1 inch outlet port that is rated at 2000 gph (for 0 head pressure) will likely not have an output of 2000 gph if the pipe/tubing used is ¾ inch or less.

This same thought goes for the UV Sterilizer itself, in fact the Custom UV I have built only uses ½ inch hose barbs so as to restrict the flow to under 350 gph which is the maximum effective rate.

It is also noteworthy that the flow rates I have already noted (20-25 gph per watt for sterilization or 40-50 gph per watt for green water control) is not an exact rule, as reflection within the UV Sterilization chamber, the distance between bulb (or sleeve) and the walls of the unit, and the length of the bulb as per wattage of UVC output all affect this general guide (this is explained later in the article in more depth).

The point as to bulb length is noteworthy, as I have found that increasing wattage with the same length bulb does NOT increase effectiveness proportionally to a given wattage. In fact a popular Pond UV that uses HO (High Output) UVC Bulbs (50 watt and 100 watt models) does not double the amount of water flow you can run through the unit even though it is double the wattage of comparable length UVC bulbs of half the wattage.

The TMC 110 Watt Pro Pond UV is much more effective than the popular HO UVs of 100 watts (each use two bulbs, the TMC uses two 55 watt of 36 inches while the “smart” HO UV uses two 50 watt bulbs of 18 inches), yet these HO UV Clarifiers cost much more which often leaves me scratching my head as to “why?”.

Cheers and Happy Reefing...

[haimi]

Thanks for your detail reply bro.

Understood the diff. flowrate for diff. sterilization level. So if the purpose is to control ich, which level should it be? Currently I have a 900l/hr and 400l/hr pump. Can I say that 900l/hr can be used for level 1 and 400l/hr for level 2 sterilization?

[CFOh]

Thanks for your detail reply bro.

Understood the diff. flowrate for diff. sterilization level. So if the purpose is to control ich, which level should it be? Currently I have a 900l/hr and 400l/hr pump. Can I say that 900l/hr can be used for level 1 and 400l/hr for level 2 sterilization?

Base on the table should be using level 2.. ~350l/hr..

How old is your tank? To control ich.. personally, I feel live stock intake control and QT.. also tank maturity playing very important rules as well..

Cheers and Happy Reefing..

[haimi]

bro, my tank is a mere 2 mths. Yes ur absolutely right that tank maturity place a very important role. last week added a blue tang and it gotta white spots so putting the uv and also to curb wide spread of the ich. Yesterday change the pump to 400l/hrs and this morning the blue tang looks better.

Thx for all the replies bro. Appreciated