Pond UV truths

Pond UV Sterilizers vs. Aquarium UV Sterilizers; is there a difference?

The answer is yes and no.
This said I have had persons over the years tell me that a store (or web site) stated that a UV sterilizer that is made for a pond is even better for an aquarium; the truth is this is generally false.

Here is what one might look for in a pond UV Sterilizer:

*Heavy duty construction so as to withstand the sun light and other elements. However any UV that is even indirectly protected form the elements (sun light, heavy rain or snow) will work fine for a pond.

*Pre filtration of debris; this is probably the most important aspect of a pond UV Sterilizer in that most ponds have higher amounts of organics in the water as well as general debris that will both clog a UV Sterilize and slow block UV effectiveness.
However even most of the UV Sterilizers specifically designed for ponds have no more ability to carry out this function than other UV Sterilizers. This function must be added by way of a pre-filter or standard pond filter by which the water passes through before the UV Sterilizer.

It should be noted that some pond UV Sterilizers come bulb “wipers”, but these gimmicks to not keep the quartz sleeve much cleaner than simply one without (they fail to remove hard water deposits well.
Some claim that a quartz sleeve is necessary for pond uv sterilizers, this is only true for very cold ponds in which algae is not generally a problem anyway (this is not to say a Quartz sleeve does is bad either as I have used many such as the Terminator that have quartz sleeves with good results). In truth units with direct contact of water (such as my Custom 15 Watt UV Sterilizer or some Aquanetics models) actually clear many ponds better in the summer. I had a recent customer go through two Tetra UV Sterilizers until trying out mine and the custom UV did a much better job (he lives in the warm summer climate of the Central Valley of California)

Lets now look at what is really needed for both aquariums AND ponds for a UV to be effective:

*For algae control an average UV Sterilizer (some need slower flow rates due to poor design) needs a flow rate of 40 gph PER watt
* For bacterial control an average UV Sterilizer (some need slower flow rates due to poor design) needs a flow rate of 20-25 gph PER watt
* For Redox control an average UV Sterilizer (some need slower flow rates due to poor design) needs a flow rate of 25-30 gph PER watt
* For parasite control an average UV Sterilizer (some need slower flow rates due to poor design) needs a flow rate of 10-15 gph PER watt (generally almost ALL UV Sterilizers work to control parasites more by indirect means such as improved water conditions such as Redox and lower suspended bacterial counts).

Now lets look at the claims of the Tetra Pond UV Sterilizer:
9 Watt UV
• Maximum water flow:
900 gallons per hour
• Maximum pond size:
1800 gallons

5 Watt UV
• Maximum water flow:
330 gallons per hour
• Maximum pond size:
660 gallons

How do they get a jump of almost triple flow for a less than double wattage increase?
Second the flow rate claims for both are outrageous for both algae or bacterial control. 900 gph calculates out to 100 gph per watt which is ridiculous, so some who purchases this for an aquarium thinking this will due a better job due to high flow rate claims is sadly mistaken.

The bottom line is do not buy a UV Sterilizer such as the one listed above for your aquarium or pond under the mistaken belief that it can handle more since it is called a pond UV. This neither true for aquariums nor ponds.
This is also not to say that the above pond UV Sterilizer does not work, however it should not be purchased based on its claim of flow or simply because it is a "Pond" UV Sterilizer as that makes little difference in real world application.

For about this subject please read this article about UV Sterilization: Aquarium and Pond UV Sterilization; how it works, truths and myths