UV Light Reflector

[KLM]

I'd like to make an inline anti-bacterial UV light filter for an aquarium by housing it inside a plastic pipe. The lamp element shines UV light into a glass tube with the water flow. To get the most of the UV light I'd like to line the inside of the pipe with UV reflector material. Aluminum foil come to mind. Is there a correct material or a better material for the reflector?

And while I am on this subject I intend to use paper coffee filters to trap the particulate waste. A bank of them should be able to handle the flow volume. When any filter is clogged I'll just toss it away and put in another one. The commercial filters using fiberglass wool, etc. clog up too quickly and are expensive to replace often. Any anticipated problems with this coffee filter approach?

When doing research on the subject I learned that areating the water with airstones dissolves too much oxygen and drives out the CO2. The lack of dissolved CO2 prevents the aquatic plants from thriving. That explains why I had so many problems with aquatic plants dying on me.

There is also a need to have a filter stage where ammonia can be removed by ammonia eating bacteria. Where is the best place to put this stage?

[m Ransley]

maybe another group , a fish tank group would help with good answers

[CAStinneford]

Is this a fresh or saltwater tank? What size? UV sterilizers in fish tanks are highly overrated. Unless you've been fishkeeping for some time, your fish will have a better chance of surviving and thriving if you use the commercial filters. Fishkeeping, fresh or salt, is not an inexpensive hobby and it's the fish that suffer if you can't afford to do it right. You'd do better to post this in one of the alt.aquaria newsgroups.

[KLM]

Fresh water tank. It will be a 60 gal acrylic tank that I will be making. The set up is a terrarium with an aquarium part on the bottom

1/4 or 1/3 and the rest will be a streamside scene full of plants and has a cascading stream. It will be stocked with fish, amphibians and perhaps some insects.

I used to keep lots of fish as a kid and they thrived with benign neglect. I don't seem to have much luck as an adult. The water in my current city is very hard.

This is a good group for home-made ideas. Since I am good at making my own things this part of the project will be as enjoyable as setting up the terrarium itself. I intend spend as little as possible ($500 max for everything) by building my own stuff. It that's not possible then I'll do something else. The homemade UV filter is a cheap way of reducing the harmful bacteria. No attempt will be made to sterilize the water completely.

[CAStinneford]

The problem with the UV is that it usually isn't in contact with the water long enough to be effective. Even if it were, it can't tell harmful bacteria from the beneficial bacteria that you need to turn the ammonia to nitrites and nitrites to nitrates. I've been breeding freshwater fish for many years and have a 90 gallon saltwater fish only tank and a 50 gallon reef so I'm not just talking through my hat. :-) Check out the alt.aquaria boards as a lot of the guys there are into DIY setups and should be able to give you some pointers. If you haven't already done it, check out some of the online sources for equipment. You can buy filter media very inexpensively online compared to your local pet stores.

Good luck with it!

[Richard J Kinch]

Glass, not plastic. Clear plastics like acrylic and polycarbonate are quickly embrittled by intense UV.

[Don Klipstein]

The antibacterial wavelengths of UV are blocked by all ordinary types of glass as well as by plastic. You will need either quartz tubing or tubing made of a special glass that lets through the 253.7 nm (AKA 254 nm) wavelength.

Unless you were thinking of immersing the bulb in water... Good luck coming up with a reliable way of getting the water to be treated directly in contact with the bulb surface but not the base(s). Also, these lamps usually work best when the coolest part of the bulb surface is around

30-50 degrees C (86-122 degrees F). This affects the concentration of mercury vapor in the bulb - too little and you get less UV, too much and mercury vapor excessively absorbs this wavelength (one other mercury UV wavelength, 184.9 nm, does this also). They are usually at a temperature close enough to optimum when operated in their usual fixtures.

- Don Klipstein ( [e-mail])