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We are in the final stages of a 5 month project of building a pond in our backyard. We have tried to do all the necessary research to build it correctly and with the right equipment, but I am stumped when it comes to a UV Clarifyer, and about the only information I can find on the Internet is price, but not a lot about the comparison between brands or types of filters (pressurized or non-pressurized, wiper or no wiper, etc.). I am hoping you or some of the forum members can provide some guidance and direction.

Our pond is a 3800 gal pond plus the water in 4 streams. I am guessing that it is around 5000-6000 gallons total. We will have some plants, goldfish and a few small Koi. We are installing a 6,700 GPH pump. We are using a skimmer and have been told we should get an in-line UV clarifier, but I can not find any site that does a comparison on them. And do I need to also buy a transformer, or do most UV clarifyers come with a transformer?

I am hoping I might get some insight from you or from your forum members and their experience and recommendations.

Hi MJohns, I cant answer your questions but wanted to welcome you to the forum. Most likely a few of the other members will be able to answer your questions shortly

You will have to post some pictures of your new pond sounds like its going to be one awesome pond with 4 streams connected to it

Happy Ponding

Hi MJohns,

Welcome to the forum.

Though similar, I have a UV sterilizer installed on my pond. I have a 57W UV lamp with a wiper and a 120W unit without the wiper. Both are connected in series to provide about 180W of UV supporting an 8000 gallon pond. The reason I have two units is one was from our original 1200 gallon pond that I reused after we completed a pond expansion project.

The difference between a sterilizer and clarifier as I understand it is a sterilizer will keep the pond crystal clear while providing bacteria control. As a clarifier your pond will still have a green tint to it unless you have 50-70% plant coverage or your pond is in full shade. In either case though neither unit can differentiate between good and bad bacteria, therefore if adding good bacteria turn the unit off for about 48 hours so the good bacteria have a chance to colonize.

The heart of each UV unit is an ultraviolet lamp sealed in a quartz glass sleeve. Quartz is used because it is purer than glass and it will not filter out the UV light given off from the bulb. Therefore, care should be taken as to not crack the UV tube. These can be expensive if you need to replace them. I have a unit that contains a quartz wiper and one that does not. I have never had any problems with the one with the wiper, but Bonnie indicated in another post that she had own two units with wipers that when used cracked the quartz sleeve. She indicated these were older units so she thought the manufacturer could have corrected the problem. In either case you should still clean the quartz sleeve periodically with muriatic acid, Lime Away or similar products to optimize the lamps effectiveness.

I never seen a UV unit not sold without some sort of transformer. My 57W unit contains an inline transformer while my 120W unit which is actually made up of three 40W bulbs is all tied through a wiring harness to a Nema box that contains the unit’s transformer. I know manufacturers sell replacement parts, the transformer being one of them.

Recently some skimmer manufactures offer units that can support UV lamps that can be installed right in the skimmer. Unless you have a small pond, I would not install a UV lamp in a skimmer since the specs for the UV lamp for these units tend to be way underpowered. The ones I’ve seen support about 30-38W of UV.

The best place to install the UV is after the filter. This way you reduce the risk of a small rock from passing over the UV and cracking the quartz sleeve.

You need to match the flow rate of your UV to your pump in order for the UV to be effective. Most manufacturers provide tables that can assist you in selecting the right size UV lamp for your needs. Ideally you would like to be able to turn over the volume of your pond once every hour. I found having more UV doesn’t hurt, but having less will take longer for it to be effective. I installed a ball valve on the input to my UV. If I find that the water is passing over the UV to fast to be effective, I can slow down the flow by adjusting the valve.

Hope this helps. Good luck.
Steve

Steve
Thanks for the info on the UV. I am researching for a pond addition as well. I do have one question. You indicated placement after the filter. Is that after a mechanical filter and b4 the bio- filter?

Murph,

I would connect after the bio-filter on the return line. This way it ensures the water is clear of debris and impurities that could inhibit the disinfection process. The UV can be installed before the filter (either bio or mechanical) but it may take longer to work and again you risk the chance of a small pebble or something passing over the quartz sleeve.

When purchasing a UV note the warranty when it comes to the quartz crystal. Some will not warranty the quartz crystal. This was one of the main reasons why I installed after the filter, didn't want to take a chance of a small pebble breaking it.

Thanks,
Steve